Search

Tsunamigenic earthquakes along the Alaska–Aleutian megathrust pose a major threat to many rural coastal communities in Alaska. To mitigate the impact of tsunamis and minimize loss of life, maximum potential runup and tsunami hazard zones need to be estimated despite a lack of the high-resolution digital elevation models. In this manuscript we present a methodology to approximate tsunami hazard zones in areas with poor topographic and bathymetric coverage. To manage a trade-off between the computational complexity and lack of quality data, we develop three scenario earthquakes with the intention that one of them characterizes impacts of a credible worst-case event. We then apply a safety factor to account for the limited number of considered scenarios and a coarse resolution elevation model used to simulate water dynamics near the community. The developed methodology is illustrated using a case study focused on the community of Adak, in the Andreanof Islands, Alaska. To validate the proposed method, we explore sensitivity of tsunami height with respect to the coseismic slip distribution and develop a comprehensive set of credible worst-case scenarios for the community. The tsunami hazard zone, developed with the use of the safety factor, is validated against high-resolution modeling of potential inundation according to the set of worst-case scenarios in a number of other coastal communities. [ABSTRACT FROM AUTHOR]

Historical documents revealed that on 27 August 1810 an earthquake affected the Loreto town and the surrounding region, along 200 km of the coast of Baja California, Mexico, and damage was considerable due to strong ground motions. However, the 1810 Loreto earthquake, unlike other earthquakes of the nineteenth and twentieth centuries, produced an extensive tsunami flooding on the eastern coast of Baja California, from Loreto to La Paz. We report here the historical account of this event and analyse the source of the related tsunami. Based on the historical record and the tectonic setting, we infer that this earthquake was produced along a transform fault, right-lateral strike slip fault, Farallon fault, on the Baja California Gulf. However, the associated tsunami was disproportionally large if compared with the earthquake intensity (IX) and approximate magnitude (7.4 Mw), fault style, and the relatively late tsunami arrival, i.e. an hour after the earthquake, suggesting that a submarine landslide, triggered by this earthquake, was the suspect source for the Loreto tsunami. We present here historical data and a numerical model of the Loreto 1810 tsunami to elucidate the source, using both the 1810 earthquake and a submarine landslide, and confirm that a submarine landslide is most likely the tsunami-triggering mechanism that followed the 1810 earthquake. [ABSTRACT FROM AUTHOR]

The July 20, 2017 Bodrum–Kos Earthquake caused tsunami wave motions and damage in the south of Bodrum Peninsula, Turkey, and on Kos Island, Greece. Immediately after the earthquake, we conducted several post-tsunami field surveys including interviews in coastal zones impacted by the tsunami, i.e., the coastlines of Bodrum Peninsula, Karaada Islet and Akyaka Town in Gökova Bay, Turkey, and eastern Kos Island, Greece. We present observations and measurements to document the variation of the tsunami effects along the coast. The largest tsunami runup was about 1.9 m and observed at the mouth of a small dry streambed at Gumbet Bay, Bodrum. No significant water motions were reported at the northern and western coasts of Bodrum Peninsula. The tsunami runup distribution along the coast of eastern Kos was overall regular, with runup not exceeding 1 m except in the Port of Kos where a 1.5 m tsunami runup was measured. [ABSTRACT FROM AUTHOR]

On 4 January 1907, an earthquake occurred off the west coast of Sumatra, Indonesia, with an instrumental surface-wave magnitude (MS) in the range of 7.5–8.0 at periods of ~ 40 s. The tsunami it generated was destructive on the islands of Nias and Simeulue, where it killed hundreds and gave rise to the legend of the S'mong. This tsunami was also observed in other parts of the Indian Ocean basin. Relative to its instrumented magnitude, the size of the tsunami was anomalous, qualifying the event as a "tsunami earthquake". However, unusually for a tsunami earthquake, the shaking on Nias was severe (7 EMS). We revisit the 1907 earthquake with a multidisciplinary approach by extracting evidence describing shaking effects or the tsunami from written documents and by acquiring new seismograms. Combining these, we discriminate two large earthquakes within an hour of each other with clear differences in seismological character. The first we interpret to be a tsunami earthquake with characteristic low levels of shaking, an estimated average seismic moment (M0) of 2.5 × 1028 dyn cm (MW ≈ 8.2) in the frequency band 6–8 mHz, and an epicentral location close to the front of the Sunda Megathrust. The seismograms we analyzed also document a regular growth of moment with period, approaching MW ≈ 8.4 at the longest resolvable period (~ 170 s). For the second earthquake that caused damage on Nias, we estimate MS ≈ 7 based on seismograms and phase data. We also identify two MS ≈ 6 aftershocks within 24 h of the mainshock. Additionally, we present a dataset of 88 locations within the Indian Ocean basin where the tsunami was observed. Using a subset of these, we forward modeled the tsunami to propose a seismic rupture model extending along the Sunda Megathrust for about 220 km (~ 94.7°E to ~ 97°E) with a maximum modeled slip of ~ 21 m. Our new rupture model provides an acceptable fit to our new dataset of tsunami runup and inundation values from 88 local and far-field locations in the Indian Ocean basin. We also urge caution against an over-reliance on the S'mong legend for tsunami evacuation as its premise, that a tsunami will only follow an earthquake with very severe ground motions, is rendered ineffective for tsunami earthquakes. [ABSTRACT FROM AUTHOR]

The five great trans-Pacific tsunamis of the 20th century that occurred in 1946, 1952, 1957, 1960 and 1964 were accurately recorded by analogue tide gauges on the coast of British Columbia. All available pen-and-paper records of these events were collected, digitised, de-tided and analysed. The 1946 Aleutian Islands event was recorded at two stations, Tofino and Victoria, where maximum trough-to-crest tsunami wave heights were 55 and 27 cm, respectively. These two gauged stations, as well as Prince Rupert, Alert Bay and Kitimat, also recorded the 1952 Kamchatka tsunami, which generated a maximum wave height of 77 cm at Tofino. The 1957 Andreanof Islands tsunami was recorded at six primary stations and the 1960 Chile tsunami by 17 primary and temporary tide gauges. For both of these events, the maximum tsunami wave heights also occurred at Tofino: 48 cm (1957) and 132 cm (1960). The 1964 Alaska tsunami remains the strongest tsunami yet instrumentally recorded on the coast of British Columbia. Our examination of 16 records from this event shows that maximum wave heights at eight stations were higher than 1 m, including Port Alberni (770 cm), Ocean Falls (376 cm), Tofino (237 cm) and Alert Bay (222 cm). We also find that the maximum wave at all stations for this event was among the first three waves. Subsequent wave heights rapidly attenuated following this group of waves. Frequency-time (f–t) analyses of the tsunami waveforms reveal that, for each station, the dominant frequencies of the waves and their evolution with time were very similar for different tsunamis, but differed considerably among sites for a particular tsunami, indicating the strong influence of local/regional topography on the incoming waves. From the latter point of view, the 1964 tsunami was exceptional. The epicentre of the 1964 Alaska earthquake was located much closer to the BC coast than for the other events and, therefore, the influence of the source was much stronger. The "ringing" of this tsunami was substantially shorter (< 1.5 days), the energy decay much faster, and the f–t diagrams at all sites more similar than for the other major events. During the 1964 event, energy associated with the dominant period of 2 h rapidly decayed. All of the tsunamis examined penetrated deep inside the narrow channels, fjords and inlets, typical of the BC coast. Waves also propagated far into some of the rivers. The 1952 Kamchatka tsunami was recorded at Kitimat, located at the head of Kitimat Arm about 80 km from Hecate Strait, while the 1957 Andreanof Islands tsunami was measured at Bella Coola, located at the remotest part of Burke Channel, a distance of ~110 km from the open ocean (Queen Charlotte Sound). The 1960 Chile tsunami was recorded at five stations located in the complex network of inlets and channels that make up the Seymour–Belize Inlet system on the central mainland coast of British Columbia, while the 1964 Alaska tsunami was observed at many stations in the Fraser River, including Pitt Lake that is connected to the Strait of Georgia through a 64-km route upstream in the Fraser and Pitt rivers. Our results further show that occasionally the fjords and inlets of the BC coast not only do not hinder the incoming waves but can strongly enhance them through resonant amplification. This was the case for the 1964 tsunami waves in Alberni Inlet, where the resonant response to the incoming waves resulted in severe damage to Port Alberni at the head of the inlet. The results of our analyses make it possible to isolate the tsunami signal and evaluate the principal parameters of tsunami waves. This, in turn, is of considerable value for three major problems: (1) Cataloguing of tsunami events; (2) estimation of the potential tsunami risk to the BC coast; and (3) verification and calibration of numerical tsunami models. [ABSTRACT FROM AUTHOR]

We revisit the source of the 1992 Flores earthquake and tsunami using finite-fault inversion. We simultaneously invert teleseismic body and surface waves together with coseismic uplift/subsidence datasets. We then verify the inverted source against tsunami run-up heights along the northern coast of Flores Island and the only tide gauge recording of the tsunami. Our preferred source model provides a good fit to all the datasets, whereas previous models only explained a subset of the available data. We show that the fault geometry implies segmentation of the back-arc thrust system in the eastern Sunda Arc. [ABSTRACT FROM AUTHOR]

Regional and global tsunami hazard analysis requires simplified and efficient methods for estimating the tsunami inundation height and its related uncertainty. One such approach is the amplification factor (AF) method. Amplification factors describe the relation between offshore wave height and the maximum inundation height, as predicted by linearized plane wave models employed for incident waves with different wave characteristics. In this study, a new amplification factor method is developed that takes into account the offshore bathymetry proximal to the coastal site. The present AFs cover the North-Eastern Atlantic and Mediterranean (NEAM) region. The model is the first general approximate model that quantifies inundation height uncertainty. Uncertainty quantification is carried out by analyzing the inundation height variability in more than 500 high-resolution inundation simulations at six different coastal sites. The inundation simulations are undertaken with different earthquake sources in order to produce different wave period and polarity. We show that the probability density of the maximum inundation height can be modeled with a log-normal distribution, whose median is quite well predicted by the AF. It is further demonstrated that the associated maximum inundation height uncertainties are significant and must be accounted for in tsunami hazard analysis. The application to the recently developed TSUMAPS-NEAM probabilistic tsunami hazard analysis (PTHA) is presented as a use case. [ABSTRACT FROM AUTHOR]

Seismological observations provide essential input parameters for numerical tsunami simulations. Here, we present source mechanism parameters, finite-fault source rupture models and numerical tsunami simulation results for the destructive October 28, 2012 Haida Gwaii-Canada (Mw 7.7) and September 16, 2015 Illapel-Chile (Mw 8.3) earthquakes and resulting tsunamis. These two earthquakes were controlled by active tectonic features along the subduction zones that had developed in response to the convergent movements of lithospheric plates. The faulting geometry (strike, dip, and rake angles), focal depth, fault dimensions, average and maximum slip values on the fault planes and seismic moments of the earthquakes are estimated by analyzing teleseismic long-period P- and SH-waves and broadband P-waveforms and using waveform inversion and hybrid back-projection methods. The obtained slip models of the earthquakes reveal heterogeneous slip distributions on fault planes with long source durations (~ 80 s and 150 s) and low stress drop values (10–15 bars). Numerical simulations of tsunami wave propagation are further performed using the uniform and non-uniform slip models and nonlinear long-wave equations in spherical coordinates. The shape and arrival times of leading tsunami waves are adequately constrained particularly with the heterogeneous slip distribution models. The general characteristics of synthetic tsunami waveforms (e.g., amplitude, shape, arrival time) calculated using the non-uniform slip model, are more consistent with the observed tsunami records than those of a uniform slip model. It is further seen that simulation results using preliminary and fast slip models for both earthquakes give only approximate early tsunami estimates; tsunami wave heights and arrival times to the coasts are mostly not well simulated. The results indicate that tsunami simulations based on finite-fault source slip models likely contribute to the determination of tsunamigenic coastal regions by revealing locations, arrival times, amplitudes, and directions of tsunami waves within a close approximation to observed records off-shore and far from the source region. They provide sufficient information to facilitate tsunami warning and mitigation challenges after the destructive earthquakes. We further suggest that joint inversions of GPS, tsunami, teleseismic and strong ground motion records and higher resolution bathymetry data are needed in order to obtain better correlations between observed and synthetic tsunami data, especially for the later arriving waves. [ABSTRACT FROM AUTHOR]

A numerical model that simulates the propagation of tsunamis produced by submarine earthquakes was applied to the Caspian Sea. The model was first applied to the June 1990 (Rudbar) earthquake and our results proved to be coherent with previous simulations. It was also applied to the Krasnovodsk earthquake (1895), which had not been simulated before, and it was found that the coastal area was flooded by a tsunami, as reported in literature. Nevertheless, it was a rather local effect since the tsunami was generated in very shallow waters. Some worst-case hypothetical earthquakes were simulated in the most seismically active regions of the Caspian. In general, both the east and west coasts of the central Caspian Sea would be the most affected by these earthquake-induced tsunamis, with potential significant effects in some cases in cities such as Baku. [ABSTRACT FROM AUTHOR]

Tsunami risk assessment is an important component of the planning for risk reduction. We considered tsunami risk as a convolution of tsunami hazard, vulnerability of the assets at risk (e.g. buildings) and the economic value exposed. For testing the model, a coastal segment at the west of Heraklion, capital city of Crete Isl., Greece, was selected. Heraklion was hit in the past by strong tectonic and volcanic tsunamis, generated along the Hellenic Arc in the Mediterranean region. The Minoan tsunami produced by pyroclastic flows during the LBA (17th century BC) great eruption of Thera (Santorini) was selected as an extreme tsunami scenario for the hazard (inundation) zone determination through numerical simulation based on Boussinesq equations for fully non-linear waves. It was found that the wave penetrates inland up to ~ 1.2 km, while the maximum water depth is ~ 14 m. The building stock was obtained from the 2011 national census data and validated with the use of orthophotomaps, field inspection and Google Maps. Building vulnerability was determined with the use of the empirical GIS tool DAMASCHE which is based on 2004 Indian Ocean tsunami building damage data and produces damage level by combining water depth and building construction types. The damage level was translated to absolute monetary loss on the basis of cost flat rates determined officially for building replacement, i.e., either reparation or reconstruction, after the destructive earthquakes in Greece during 2014. The method is applicable in other parts of the Mediterranean and beyond provided that appropriate data are available. [ABSTRACT FROM AUTHOR]

Field observations provide valuable data regarding nearshore tsunami impact, yet only in inundation areas where tsunami waves have already flooded. Therefore, tsunami modeling is essential to understand tsunami behavior and prepare for tsunami inundation. It is necessary that all numerical models used in tsunami emergency planning be subject to benchmark tests for validation and verification. This study focuses on two numerical codes, NAMI DANCE and FLOW-3D®, for validation and performance comparison. NAMI DANCE is an in-house tsunami numerical model developed by the Ocean Engineering Research Center of Middle East Technical University, Turkey and Laboratory of Special Research Bureau for Automation of Marine Research, Russia. FLOW-3D® is a general purpose computational fluid dynamics software, which was developed by scientists who pioneered in the design of the Volume-of-Fluid technique. The codes are validated and their performances are compared via analytical, experimental and field benchmark problems, which are documented in the "Proceedings and Results of the 2011 National Tsunami Hazard Mitigation Program (NTHMP) Model Benchmarking Workshop" and the "Proceedings and Results of the NTHMP 2015 Tsunami Current Modeling Workshop". The variations between the numerical solutions of these two models are evaluated through statistical error analysis. [ABSTRACT FROM AUTHOR]

Over the past decade, the number of open-ocean gauges capable of parsing information about a passing tsunami has steadily increased, particularly through national cable networks and international buoyed efforts such as the Deep-ocean Assessment and Reporting of Tsunami (DART). This information is analyzed to disseminate tsunami warnings to affected regions. However, most current warnings that incorporate tsunami are directed at mid- and far-field localities. In this study, we analyze the region surrounding four seismically active subduction zones, Cascadia, Japan, Chile, and Java, for their potential to facilitate local tsunami early warning using such systems. We assess which locations currently have instrumentation in the right locations for direct tsunami observations with enough time to provide useful warning to the nearest affected coastline—and which are poorly suited for such systems. Our primary findings are that while some regions are ill-suited for this type of early warning, such as the coastlines of Chile, other localities, like Java, Indonesia, could incorporate direct tsunami observations into their hazard forecasts with enough lead time to be effective for coastal community emergency response. We take into account the effect of tsunami propagation with regard to shallow bathymetry on the fore-arc as well as the effect of earthquake source placement. While it is impossible to account for every type of off-shore tsunamigenic event in these locales, this study aims to characterize a typical large tsunamigenic event occurring in the shallow part of the megathrust as a guide in what is feasible with early tsunami warning. [ABSTRACT FROM AUTHOR]

The consideration of uncertainties in flood risk assessment has received increasing attention over the last 2 decades. However, the assessment is not reported in practice due to the lack of best practices and too wide uncertainty bounds. We present a method to constrain the model roughness based on measured water levels and reduce the uncertainty bounds of a two-dimensional hydrodynamic model. Results show that the maximum uncertainty in roughness generated an uncertainty bound in the water level of 1.26 m (90 % confidence interval) and by constraining roughness, the bounds can be reduced as much as 0.92 m. [ABSTRACT FROM AUTHOR]

Seismogenic tsunami hazard assessments are highly dependent on the reliability of earthquake source models. Here in a study of the Manila subduction zone (MSZ) system, we combine the geological characteristics of the subducting plate, geometry, and coupling state of the subduction interface to propose a series of fault rupture scenarios. We divide the subduction zone into three rupture segments: 14–16, 16–19, and 19–21.7 ∘ N inferred from geological structures associated with the down-going Sunda plate. Each of these segments is capable of generating earthquakes of a magnitude between Mw=8.5+ and Mw=9+ , assuming a 1000-year seismic return period as suggested by previous studies. The most poorly constrained segment of the MSZ lies between 19 and 21.7 ∘ N, and here we use both local geological structures and characteristics of other subduction zone earthquakes around the world, to investigate the potential rupture characteristics of this segment. We consider multiple rupture modes for tsunamigenic earthquake and megathrust-splay fault earthquakes. These rupture models facilitate an improved understanding of the potential tsunami hazard in the South China Sea (SCS). Hydrodynamic simulations demonstrate that coastlines surrounding the SCS could be devastated by tsunami waves up to 10 m if large megathrust earthquakes occur in these segments. The regions most prone to these hazards include west Luzon of Philippines, southern Taiwan, southeastern China, central Vietnam, and Palawan Island. [ABSTRACT FROM AUTHOR]

Fourteen years ago, the 26 December 2004 Indian Ocean tsunami demonstrated the destructional capability of tsunamis to the entire world. Since then, many research programs have been initiated to try to understand the phenomenon and its related hazards better and to improve the early warning systems for exposed coastal populations. Pacific Islands Countries and Territories (PICTs) are especially vulnerable to tsunamis. Amongst them, New Caledonia is a French overseas territory located in the Southwest Pacific and exposed to several tsunami sources. In 2010, a catalogue of tsunamis that were visually observed or measured in New Caledonia was published. Since this first study, several events occurred between 2009 and 2019, and an update of this catalogue was necessary within the framework of a tsunami hazard assessment project in New Caledonia (TSUCAL). To complete this catalogue, a decision table has been designed to select potential tsunamigenic events within the USGS earthquake database, using criteria on the distance to New Caledonia, the magnitude and the hypocenter depth. Then a cross-comparison between these earthquakes, the NOAA National Geophysical Data Center (NGDC) tsunami catalogue and local tide gauge records provided 25 events that were recorded in New Caledonia for the period from 30 September 2009 to 10 January 2019. These events are added to the 12 events reported with certainty during previous studies, leading to a number of 37 tsunamis triggered by earthquakes reported or recorded in New Caledonia since 1875. Six of them have been identified only thanks to local tide gauges, supporting the fact that instrumental recording of tsunamis is paramount for tsunami hazard studies, from early warning to the validation of coastal models. In addition, unpublished tide gauge data are provided for the 1960 Chile tsunami. [ABSTRACT FROM AUTHOR]

The study of volcanic flow hazards in a probabilistic framework centers around systematic experimental numerical modeling of the hazardous phenomenon and the subsequent generation and interpretation of a probabilistic hazard map (PHM). For a given volcanic flow (e.g., lava flow, lahar, pyroclastic flow, ash cloud), the PHM is typically interpreted as the point-wise probability of inundation by flow material. In the current work, we present new methods for calculating spatial representations of the mean, standard deviation, median, and modal locations of the hazard's boundary as ensembles of many deterministic runs of a physical model. By formalizing its generation and properties, we show that a PHM may be used to construct these statistical measures of the hazard boundary which have been unrecognized in previous probabilistic hazard analyses. Our formalism shows that a typical PHM for a volcanic flow not only gives the point-wise inundation probability, but also represents a set of cumulative distribution functions for the location of the inundation boundary with a corresponding set of probability density functions. These distributions run over curves of steepest probability gradient ascent on the PHM. Consequently, 2-D space curves can be constructed on the map which represents the mean, median, and modal locations of the likely inundation boundary. These curves give well-defined answers to the question of the likely boundary location of the area impacted by the hazard. Additionally, methods of calculation for higher moments including the standard deviation are presented, which take the form of map regions surrounding the mean boundary location. These measures of central tendency and variance add significant value to spatial probabilistic hazard analyses, giving a new statistical description of the probability distributions underlying PHMs. The theory presented here may be used to aid construction of improved hazard maps, which could prove useful for planning and emergency management purposes. This formalism also allows for application to simplified processes describable by analytic solutions. In that context, the connection between the PHM, its moments, and the underlying parameter variation is explicit, allowing for better source parameter estimation from natural data, yielding insights about natural controls on those parameters. [ABSTRACT FROM AUTHOR]

Flood modeling at the regional to global scale is a key requirement for equitable emergency and land management. Coupled hydrological‐hydraulic models are at the core of flood forecasting and risk assessment models. Nevertheless, each model is subject to uncertainties from different sources (e.g., model structure, parameters, and inputs). Understanding how uncertainties propagate through the modeling cascade is essential to invest in data collection, increase flood modeling accuracy, and comprehensively communicate modeling results to end users. This study used a numerical experiment to quantify the propagation of errors when coupling hydrological and hydraulic models for multiyear flood event modeling in a large basin, with large morphological and hydrological variability. A coupled modeling chain consisting of the hydrological model Hydrologiska Byråns Vattenbalansavdelning and the hydraulic model LISFLOOD‐FP was used for the prediction of floodplain inundation in the Murray Darling Basin (Australia), from 2006 to 2012. The impacts of discrepancies between simulated and measured flow hydrographs on the predicted inundation patterns were analyzed by moving from small upstream catchments to large lowland catchments. The numerical experiment was able to identify areas requiring tailored modeling solutions or data collection. Moreover, this study highlighted the high sensitivity of inundation volume and extent prediction to uncertainties in flood peak values and explored challenges in time‐continuous modeling. Accurate flood peak predictions, knowledge of critical morphological features, and an event‐based modeling approach were outlined as pragmatic solutions for more accurate prediction of large‐scale spatiotemporal patterns of flood dynamics, particularly in the presence of low‐accuracy elevation data. Plain Language Summary: Floods are among the most devastating natural hazards, affecting multiple regions and millions of people each year. Accurate inundation predictions are vital information for land and emergency management. This objective can be achieved through a cascade of numerical models. However, each model is subject to uncertainties from different sources (e.g., input data, model structure, and parameters), and an understanding of how these uncertainties are propagated through each step of the modeling cascade is pivotal to improving inundation prediction accuracy. This study investigated the impact of uncertainties in streamflow predictions on the accuracy of floodplain inundation predictions. For this purpose, the Murray Darling Basin (Australia), a large basin that is affected by destructive floods, was used as a case study. The analysis illustrated the high sensitivity of floodplain inundation predictions to predicted streamflow peak values. Moreover, when attempting to model a long time series of low‐ and high‐flow periods, uncertainties in the inundation patterns increased over time and from upstream to downstream areas of the basin. These results demonstrated the need for accurate predictions of streamflow peak values and suggested that focusing on the modeling of each large flood event separately is a more effective strategy for reliable inundation predictions. Key Points: A numerical experiment was used to improve understanding of uncertainty propagation in coupled hydrologic‐hydraulic modelsDiscrepancies in measured and simulated flow peaks lead to large uncertainties in predicted floodplain inundation volumes and extentThe challenges of multiyear continuous modeling are highlighted with an event‐based approach recommended [ABSTRACT FROM AUTHOR]

The main objective of this research is to prepare inundation map of a section of Babai Basin and to find out the inundated areas for different return periods. In order to achieve the objectives, Geographic Information System (GIS) and HEC-RAS along with HEC-GeoRAS extension were used as tools. Coordinates were used as primary parameter and were obtained from survey to generate geometric data such as Triangular Irregular Networks (TIN), streamline, river bank and flow paths. After importing the geometry data into HEC-RAS, hydraulic modelling was applied by using flow data as main input. As a result, the watershed area of the Babai basin has been successfully modelled and map showing the flooded areas along the Babai basin has been delineated. The flooded area was geometrically overlaid on the topographic map to outline the affected areas. The area under the influence of the flood were assessed which shows that about 49% of total inundated areas comprises farming land. Also a sensitivity analysis was performed to predict the change in percentage of flooded areas when Maning's parameter was increased by 10% and when kept same in both banks and channel. However, differences in figure of inundated areas are insignificant to variations made in Maning's n. [ABSTRACT FROM AUTHOR]

This study presents the first tsunami scenario database in Marmara Sea, Turkey referring to 30 different earthquake scenarios obtained with the combinations of 32 possible fault segments. The fault mechanisms in Marmara Sea have been studied in detail within FP-7 MARSite project, which were derived from various databases and literature review. Tsunami simulations have been performed according to these defined 30 earthquake scenarios by tsunami numerical code NAMI DANCE (NAMIDANCE, 2011) which solves Nonlinear Shallow Water Equations (NLSWE) using leap-frog scheme. For each earthquake scenario, tsunami hydrodynamic parameters, mainly maximum water surface elevations, arrival time of first wave and maximum wave, and water level fluctuations were calculated at 1333 synthetic gauge points meticulously selected along the coasts of Marmara Sea. The overall simulation results indicate that maximum expected wave heights due to these earthquake scenarios are between 1 m and 2 m and even more than 2 m at some locations along Marmara coasts, such as Kadikoy, Halic and Silivri coasts in Istanbul and Bayramdere and Kursunlu districts along the coasts of Bursa province. The estimated maximum water levels at Bostanci, Pendik and Buyukada coasts in Istanbul, Cinarcik and Bandirma towns and at the entrance of Izmit Bay would reach up to 2 m. Tekirdag coasts and Buyuk Cekmece and Bakirkoy coasts in Istanbul and Yalova coasts would experience maximum tsunami wave amplitudes around 1.5 m. The waves reach up to 1 m at Izmit and Gemlik Bays, Erdek Peninsula and Marmara Island. The overwiew of the results reveal that higher historical tsunami wave heights observed in Marmara Sea cannot be explained by only earthquake-generated tsunamis. Therefore, there is strong agreement on considering submarine landslides as the primary tsunami hazard component in the Marmara Sea as experienced during history and expected in the future. [ABSTRACT FROM AUTHOR]

This article presents improvements and development of a post-processing module for the regional scale flood mapping tool, AutoRoute. The accuracy of this model to simulate low, medium, and high flow rate scenarios is demonstrated at seven test sites within the U.S. AutoRoute is one of the tools used to create high-resolution flood inundation maps at regional- to continental-scales. The model has previously only been tested using extreme flood events. In this article flood inundation results for low-flow events are shown to be accurate (average F value of 63.3 %) but tend to be overestimated, especially in flatter terrain. Higher-flow scenarios tend to be more accurately simulated (average F value of 77.5 %). Additionally, modifications to the AutoRoute model and post-processing scripts are shown to improve computational efficiency (i.e. simulation time) by over 40 % when compared to previous versions. With improved computational efficiency and the ability to accurately simulate both low and high flow scenarios the AutoRoute model may be well suited to provide first-order estimates of flooding within an operational, regional- to continental-scale hydrologic modelling framework. [ABSTRACT FROM AUTHOR]

The North Atlantic coast of Morocco has been affected historically by marine submersion events resulting from both storms and tsunamis and causing human and economic losses. The development of proactive adaptation strategies requires the study of these events over centennial to millennial timescales. Using a 2.7 m sediment core sampled from the Tahaddart estuary, we have been able to reconstruct past marine submersion events on this coastal area of Morocco over the last 4000 years. The high-resolution sedimentological and geochemical analysis conducted on this core allows us to identify 14 sediment layers attributed to marine high-energy events. The core was dated with isotopic techniques (137Cs, 210Pbex, 14C) and the outcomes reveal that three sediment layers are in connection with two major historical marine submersion events. The first layer mentioned as E1 seems to fit with the great Lisbon tsunami in 1755 CE (Common Era), an event dated for the first time on the Atlantic coast of Morocco. The other two layers referred as E13 and E14 were dated between 3464 and 2837 cal BP and correlated with marine submersion deposits found on Spanish and Moroccan coasts, which confirms the existence of a major high-energy event (around 3200 BP) similar to the one in 1755 CE. [ABSTRACT FROM AUTHOR]

The frequent occurrence of landslide tsunami has aroused great social concern, hence an efficient approach for modeling the phenomena is required urgently. Herein, we present and supplement a meshless numerical model named 'Tsunami Squares' (TS). TS simulates both the landslide and its generated wave using an updated numerical scheme that has enhanced computational efficiency. TS also provides an artful way of approximating linear dispersive wave propagation and non-linear wave inundation that makes it quite capable of simulating real-scale events. A well-designed test that compares TS output with an analytical formula for a tsunami propagation calculation provides firm validation of the approach. We then applied the 'Tsunami Squares' to simulate the 1792 Unzen-Mayuyama mega slide and generated tsunami. This event remains the largest volcanic disaster in the history of Japan. Landslide dynamics simulated by TS coincide with historical reports and the known geometry of landslide deposits. The model output of tsunami runup heights well match the observed values recorded by the locations of historical 'Tsunami Stones'. This well documented and data-rich case further validates the 'Tsunami Squares' model and the excellent reproduction of the 1792 event provides new insights for better understanding of landslide tsunami hazards. • Development of a new model for linear and non-linear wave propagation and inundation • Model validation with an analytical formula of a Gaussian water pile propagation • Model application to the data-rich 1792 Unzen-Mayuyama landslide tsunami • Features of energy dissipation in landslide and its generated tsunami dynamics [ABSTRACT FROM AUTHOR]

In this study we use a scenario-based approach to highlight potential tsunami hazard from actual Late Pleistocene submarine landslides in the Ulleung Basin: two submarine landslides on the western slope of the Ulleung Basin, north and south of the Hupo Bank (2.53 and 1.12 km3 respectively) and a landslide (15.1 km3) on the continental slope south of the Ulleung Basin. The simulations attempt to highlight the consequences, should one of these events occur at Present. Results of the simulations indicate potential local hazard zones with very local waves < 2 m high in the Korean coast of the East Sea that could result from midsized landslides, not exceeding 3 km3 on the western slope of the basin. Time available for early warning since onset of these events is between 15–30 minutes. On the other hand, the continental margin south of the Ulleung Basin is an area where landslide tsunamis with significant hazard potential could originate. New landslides of similar size to those of the Late Pleistocene could produce tsunami waves > 3 m in the stretch of coastline from Ulsan in the south to Uljin in the north. The timing available for early warning from landslide tsunamis originating in this area is 15–30 minutes along the affected section of the shoreline. We also suggest a Probabilistic Tsunami Hazard Assessment (PTHA) for comprehensive assessments of the Korean coast of the East Sea. PTHA accounts for uncertainties in location, release mechanisms, evolution, and return periods of submarine landslides as well as epistemic uncertainty. However, to constrain these uncertainties detailed information on source areas, recurrence period and dynamics of submarine landslides is necessary and calls for additional data collection and further studies. [ABSTRACT FROM AUTHOR]

A probabilistic flood risk modelling chain is proposed for flood risk analysis with consideration of spatial spreading and temporal clustering of the flood events. The proposed method consists of (1) a continuous simulation of long-term climatic and hydrologic fields, (2) Monte-Carlo simulations of a 1D river and inundation model and (3) a probabilistic loss model. In the first stage, three multisite multivariate weather generators were tested and a K-nearest neighbor weather generator (KNN-CAD v4) was found most suitable to reproduce hydrological extremes. The methodology was then applied to identify variations in risk between spatially coherent and simplified event sets generated from 5000 years of synthetic data across four river basins in Uttarakhand, India. The results showed that preserving the spatial coherency of regional events lead to a spreading of the T-year local event distributions on both sides of a uniform regional T-year return period. The specificity of the exposure and the correlations between local events translated into minimal (4%) differences in losses at high return periods (> 50 year) but larger difference (20%) at low return periods (5 to 10-year). The redistribution of loss frequencies led to negligible differences in the Annual Average Losses between the different event sets. In this application, a simplified event set structure with uniform but appropriate T-year return periods proved to capture reasonably well the averaged risk metrics regionally. This study illustrates the complexity of estimating regional flood risk accumulation and exemplifies how a probabilistic risk model chain with continuous simulation can provide a more detailed picture of flood risks. [ABSTRACT FROM AUTHOR]

Bali is highly susceptible to earthquake-generated tsunamis. The island attracts millions of visitors each year, yet little is known about tourists' tsunami information sources prior to and while visiting Indonesia, perceived causes of tsunamis, perceptions of tsunami evacuation windows, and evacuation intentions. We created inundation maps for high-tourist areas of Bali, conducted multiple-choice surveys of tourists in English, Japanese, and Chinese, conducted informal interviews of hotel and government officials, and assessed topography of high tourist areas for safe evacuation sites. 75.3% of tourists reported that they had not learned about tsunamis while traveling in Indonesia. 24.3% had not learned about tsunamis prior to traveling to Indonesia. 84.2% recognized that tsunami events could be triggered by earthquakes; however many incorrectly attributed tsunami causes to events such as storms (24.7%), climate change (22.0%), and lunar gravitational pull (12.8%). Although our numerical model showed a 15–20 min evacuation window after earth shaking, 42.1% of tourists believed they would have more than 30 min to evacuate. Most participants reported intentions to run uphill (85.5%), inland (42.8%) or up the stairs of a tall building (34.2%). There is increased opportunity for government and tourism providers to disseminate knowledge of tsunami natural warning signs and specific evacuation instructions at airports, hotels, beaches, and tourism websites. Due to Bali's topography, these educational efforts may not be effective unless additional Temporary Evacuation Shelters are built in high tourist areas lacking hills. Additional disaster mitigation recommendations are provided. [ABSTRACT FROM AUTHOR]

Ho Chi Minh City gets severely inundated by upstream flooding and a combination of rising spring tides and rain, owing to the combined impacts of rapid urbanization and sea level changes. A sea dike to close Can Gio Bay has been proposed to regulate storage and control water levels in the drainage and sewer system of Ho Chi Minh City. However, this proposed sea dike and different gate operating modes could significantly change the hydrodynamic regime in Can Gio Bay. In this study, a two-dimensional hydrodynamic model was developed to assess changes in the hydrodynamic regime after construction of the sea dike, including fluctuations in the inundated areas in Can Gio Bay mangrove forests. The results show that sea dike construction is an effective solution for controlling water levels and reducing inundation, especially considering a sea level rise scenario in the year 2050. Further, the gate operation mode also affects the effectiveness of inundation reduction, which is approximately 10% better than the same sea dike type without gate operation. However, the sea dike was less effective in a sea water level rise scenario in 2100 for all scenarios. [ABSTRACT FROM AUTHOR]

Hurricanes Irma and Maria caused catastrophic damages across the Caribbean Islands during the 2017 hurricane season. After the storms, a joint United States–Japanese team investigated coastal impacts in the US Virgin Islands, which are composed of the islands of St. Thomas, St. John, Water Island, and St. Croix. Coastal inundation was dominated by wave run-up in almost all locations, with many locations showing inundation exceeding 4-m elevation from mean sea level. In contrast, maximum elevations recorded at tide gauges did not exceed 1 m at any location. Coastal damage was relatively minor for such strong hurricanes because of the lack of heavy development at low elevations on the most exposed coastlines. Many moored vessels were destroyed, and coastal structures and infrastructure within the inundation region suffered significant damage. However, few large structures experienced catastrophic losses from coastal inundation. In contrast, strong winds caused extensive structural damage throughout the US Territory. Evidence was seen for past inundation of the coastline, but could not be conclusively linked to any particular events. [ABSTRACT FROM AUTHOR]

The scope of this study is to investigate the effect of the kinematic rupture process on tsunami propagation and corresponding tsunami hazards in coastal regions. It is significant for the tsunageneric earthquakes of long fault length and subsequent long duration of the fault rupture in the strike direction. Most previous studies on the tsunami hazard assessments of the Manila Trench did not consider the effect of the rupture process of huge plates. The movements of the seabed near the earthquake source are calculated by Okada model. The free surface elevation triggered by the seafloor motion is modeled by the nonlinear shallow water equations. The 2004 Indian Ocean tsunami and the 2011 Japan Tohoku tsunami are used to validate the numerical model by comparing with measurement data. The numerical experiments of the tsunami propagation for the cases of different source rupture velocities in uniform depth and continental shelf are carried out to understand the mechanism of the changes of the tsunami arrival time and the tsunami amplitude due to the kinematic rupture process. Stimulated by the long duration of plate motion of 2004 Indian Ocean tsunami, we propose several typical patterns of the rupture process of the long fault of the Manila Trench and analyze quantitatively on the role of the uncertain rupture process of tectonics source in tsunami propagation in the South China Sea. Our results have highlighted that the slow rupture velocity will remarkable affect the tsunami arrival time and maximum amplitude in the South China Sea, comparing to the instantaneous rupture. It is suggested that the rupture process is essential for assessments of the tsunami hazards generated by submarine mass failure with extreme long earthquake rupture source. • The 2004 Indian Ocean tsunami and 2011 Japan Tohoku tsunami are simulated by using the dynamic source model. • Numerical experiments depict the changes of the tsunami amplitude and the arrival time due to different rupture velocities. • The kinematic effect of the rupture process on the propagation of a virtual extreme tsunami in the Souh China Sea is investigated. [ABSTRACT FROM AUTHOR]

Abstract Flood-inundation modelling is essential for understanding flood dynamics and implementing flood risk management. Despite its increasing demands, it remains computationally expensive to perform 2-D flood-inundation simulations at large scales or fine spatial resolutions. This study presents a simple and novel algorithm for 2-D flood-inundation modelling, called the Automatic Domain Updating method, which dynamically updates the simulation domain of a 2-D flood-inundation model. The method limits the simulation domain where governing equations are solved to flooded areas in each time step by tracking the location of wet and dry interfaces. The proposed algorithm was tested in an actual river basin for different types of flooding. The results show that the ADU method regulates the simulation domain to flooded areas and slashes the computational time for grid-based 2-D flood-inundation simulations typically by 5%–20%, with correspond to the ratio of flooded area to the whole simulation domain. [ABSTRACT FROM AUTHOR]

• Dryland wetland vegetation responds to inundation depth, duration and frequency. • Hydrodynamic modelling identifies if inundation requirements of vegetation are met. • Satellite/field data help detect inundation thresholds for vegetation transition. • Terrestrial vegetation invades wetlands after 4 years of inundation below threshold. Dryland wetlands receiving periodical floods are of key importance for ecological resilience. The inundation regime (i.e., frequency, duration, depth, and timing of inundation), is one of the major factors that determine the suitability of local conditions for specific wetland species. During droughts, inundation conditions can reach a threshold after which wetland vegetation could transition to dryland vegetation. This study analyses the response of vegetation to hydrologic variability in an arid wetland in Australia over a period of 22 years (including the Millennium drought) in order to identify inundation thresholds for transitions. We use numerical modelling, field observations and remote sensing data to relate continuous detailed simulations of the inundation regime with the response of patches of Common reed, Water couch and River red gum, three key vegetation associations in the study site. We focus in patches that were affected by the drought and presented dryland vegetation invasion as well as reference patches that remained healthy throughout the drought. On each patch, we compare annual and inter-annual simulated inundation regimes to the minimum inundation conditions that can support the specific vegetation, and we compute the percentage area of the patch that verifies minimum inundation for each year. We define this area percentage as minimum inundation index. This index is analysed in conjunction with Landsat derived information on green vegetation coverage (green Seasonal Fractional Cover) for the selected patches. We found that the minimum inundation index and inter annual frequency are able to describe the vegetation dynamics of the patches, which can be characterised by two distinct response modes that depend on a threshold value of the minimum inundation index. Inundation below the threshold noticeably leads to degraded vegetation, but the vegetation can recover quickly if this threshold is later maintained for one or two years. Values below the threshold for more extended periods (drought) result in a gradual decrease of wetland vegetation to almost complete disappearance after four years and subsequent dryland vegetation invasion. [ABSTRACT FROM AUTHOR]

• Presents a typology of emergent risk that highlights the iterative and inter-related nature of climate change risk, and propensity for impacts, such as legal action and reduced debt access, to emerge subsequent to, yet far removed from, initial physical impacts. • Highlights current practice and gaps in local government risk management concerning emergent risk. • Highlights the potential and need for local government to consider, the application of risk transfer mechanisms such as catastrophe bonds in the face of historical and conceivable climate change-perpetuated reduced access to, and increased cost of, traditional mechanisms such as insurance. • Provides insight into barriers and enablers to local government agencies gaining an appreciation of the potential application of alternative risk transfer mechanisms. Insurance represents an integral part of local government risk management strategy. As climate change progresses, increased loss and risk related to extreme weather events such as tropical cyclones, could motivate insurers to withdraw from certain markets. In some regions, such a withdrawal represents an emergent risk that, when coupled with increasing populations and other climate change impacts, could leave local governments and ratepayers particularly vulnerable. This paper investigates such a scenario and its ramifications in the context of a region particularly vulnerable to climate change, through an exploration of the degree that consideration of emergent risks, such as loss of insurance, and the potential application of insurance alternatives influence Queensland local government risk management. The study finds little appreciation amongst government officials of emergent risk implicit in extreme weather events such as cyclones, little understanding of the nuances of risk transfer mechanisms beyond familiar traditional insurance and disaster funding mechanisms, and by default, a lack of appreciation of the relationship between the two. A lack of resource and leadership with respect to emergent risk, and an absence of dialogue between insurance brokers and local government concerning climate change risk arise as the main reasons for this result. This research is significant because it challenges current local government risk management practice through an exploration of the risks inherent in the process itself. This has potential social, economic and ecological ramifications in drawing attention to aspects of possible "uninsurability" and prospects of alleviation thereto. Further research is recommended to consider the insurance industry's part in this study's findings in order to inform current industry practice and thinking and further enlighten the causes of local government disengagement in this critical area. [ABSTRACT FROM AUTHOR]

In response to warming winter air temperatures, freeze-sensitive mangrove forests are expected to expand at the expense of freeze-tolerant salt marshes. To better anticipate and prepare for mangrove range expansion, there is a need to advance understanding of the modulating role of microclimate. Here, we synthesized hypotheses regarding the effects of microclimatic variation on temperature gradients and mangrove freeze damage. Temperature data from the literature and from temperature loggers were used to quantify ecologically relevant temperature gradients. Then, literature-derived mangrove freeze damage data were used to quantify the ecological effects of these temperature gradients. Six microclimatic factors are described that produce air temperature gradients that modulate mangrove responses to winter temperature extremes: (1) distance from the ocean; (2) distance from wind buffers; (3) mangrove canopy cover; (4) height above the soil surface; (5) local slope concavity; and (6) tidal inundation. Variation in these factors produces local temperature differences that range from 2 to 14 °C, with concomitant effects on horizontal and vertical patterns of biological damage from freezing. Collectively, our results elucidate the influence of microclimate on spatial patterns of biological damage and mortality due to winter temperature extremes. As mangrove ranges expand in response to climate change, we anticipate that microclimatic variation will produce adverse environments where mangrove expansion is prohibited as well as expansion hot spots where mangroves are protected. Subsequent expansion into newly available habitat will occur from protection zones, and microclimatic gradients may even produce positive feedback cycles that ultimately accelerate the rate of range expansion in response to warming. [ABSTRACT FROM AUTHOR]

On 28 September 2018, a Mw 7.5 earthquake struck Sulawesi Island, soon followed by a destructive tsunami. This study provides a case history of tsunami deposition where submarine landslides or coastal collapses have contributed to and intensified tsunami generation. The sedimentary features resulting from this complex tsunami mechanism are not yet well understood. We surveyed tsunami deposits at six locations along the coastline of Palu Bay, in addition to measuring tsunami flow depth, run-up height, and inundation distance at each site. In general, the tsunami height was less than 8 m with a maximum inundation distance of 310 m. The tsunami deposits are thin with simple sedimentary structures such as fining upward sequences. These sedimentary characteristics are typical of tsunami deposits elsewhere around the world. This work is a preliminary study, in that numerical modeling including sediment transport has not been performed. Further work is needed to distinguish tsunamis with different source mechanisms. [ABSTRACT FROM AUTHOR]

The simulation speed of two‐dimensional hydrodynamic flood models is a limiting factor when catchments are large, a considerable number of simulations is required (e.g., exploratory modeling, Monte‐Carlo flood simulations, or predicting probabilistic flood maps), or when there is a need for real‐time flood emergency management. Rapid Flood Models (RFMs) that rely only on topographic depressions and the water balance equation have been successfully implemented to predict maximum urban flood inundation depths within seconds to a few minutes. However, the preprocessing step (identification of depressions and their attributes) and the postprocessing step (marking up possible flow paths of flood water in between flooded depressions) of RFMs is time consuming. In this study, we developed a new fast flood inundation model based on the cellular automata (CA) approach. The new model does not require the preprocessing and postprocessing steps of RFMs and therefore can provide more simulation speed. The performance of our new model, referred to as Cellular Automata fast flood evaluation (CA‐ffé), was compared to two well‐known hydrodynamic flood models (HEC‐RAS and TUFLOW) in 20 simulation experiments conducted in five different urban subcatchments. CA‐ffé predicted maximum inundation depth with reasonable accuracy in a matter of seconds to a few minutes for a single rainfall event simulation. The CA‐ffé model performed exceptionally well in areas with low‐lying depressions. However, in areas where floodwaters had higher momentum and velocity, the model usually was not able to estimate inundation depths calculated by HEC‐RAS or TUFLOW. CA‐ffé's key drawback is also its inability to represent the temporal evolution of flooding and flow velocities. Nevertheless, its ability to provide spatial flood extents and depths in a fraction of the time compared to its hydrodynamic counterparts is a significant advancement toward exploratory approaches for water systems planning, model‐based predictive control, and real‐time flood management. Key Points: A rapid urban flood inundation model was developed using a novel cellular automata approach and tested against detailed hydrodynamic modelsOur model successfully predicted maximum inundation depth caused by excessive rain and stormwater surcharges within seconds to a few minutesSelecting appropriate ranges for the model's parameters is crucial for model performance [ABSTRACT FROM AUTHOR]

Abstract The potential tsunami hazard for atoll islands inside the South China Sea (SCS) has not been investigated previously. In this study, we assess the tsunami hazard for the Xisha Archipelago using a deterministic approach. The tsunami source considered in this study is hypothesized earthquakes in the Manila subduction zone. We employ COMCOT (COrnell Multi-grid Coupled Tsunami model) for tsunami simulations. Different with previous deterministic assessments, our study investigates the uncertainties caused by bathymetric resolution and rupture complexities (here refers to rupture speed and direction variations related to fault geometry complexity). Comparison between results of different resolution suggests that coarser grids may over/underestimate tsunami hazards around mid-ocean atoll islands and this depends on the surrounding bathymetry. But results of different datasets show that GEBCO may lead to a lower result than the multibeam data. We also investigate the uncertainties caused by different rupture speed and direction, which are highly affected by subducting seamounts/ridge. Different rupture direction will shift the hardest hit locations to areas, which are possibly underestimated in cases of instantaneous ruptures. Also, the distribution of slip and location of the rupture zone can affect the local tsunami wave height significantly. We suggest that near-island high-resolution bathymetric data and dynamic rupture process should be considered in future tsunami hazard assessment in locations with similar geological structures. Highlights • Tsunami hazard evaluation inside the SCS is taken for the first time, mainly focusing on the small scattered reef islands. • Tsunami hazard on atoll islands may be over/underestimated when using low-resolution bathymetry data. • Rupture complexity related to seamounts/ridge subduction along the Manila trench should be taken into consideration. [ABSTRACT FROM AUTHOR]

Abstract Densely populated coastal regions are vulnerable to threats associated with climate change and variability, especially storms. In the United States, millions of people are repeatedly at risk of flooding and because this number will only continue to grow, the identification of the intersection of social vulnerability and physical risk to flood inundation is essential for both coastal planning and adaptation purposes. Although a key tool to identify vulnerable populations, most vulnerability models are built at the county or coarser scales, thereby hindering the effectiveness of mitigation and adaptation planning at community scales, which are more socially and physically diverse than what county-scale analyses can reveal. We present an integrated social and physical model of vulnerability at the block-group level of geography using census data to measure social variability based population and housing data and physical exposure based on the intersection of finished floor elevation of all buildings in coastal North Carolina, USA with flood hazards maps. We identify, in a spatially-explicit manner and at multiple levels of governance, areas of high social vulnerability and their intersection with areas of high physical exposure to inundation. We found that in the 28 coastal counties of North Carolina, 45.3% of the structures within the 100-year floodplain were structurally exposed to potential damage from inundation. Supporting our hypothesized patterns of vulnerability to inundation, a significant clustering of highly vulnerable block-groups were located in Albemarle and Eastern Carolina coastal regions, yet high vulnerability outliers were also located at significant distance away from the highly physically-exposed coastline. Our findings suggest that the high-resolution block-group level analysis identified multiple levels of vulnerability to inundation at the sub-county scale and provide essential information for effective hazard mitigation within scales ranging from the community to transboundary governing bodies. Highlights • Finished-floor elevation NC dataset allows for unprecedented analysis of flood risk. • 45% of buildings in coastal Carolina built at or below mandated base-flood elevations. • 27% of block-groups in coastal NC are at high risk of flooding. • Combining building flood risk and social vulnerability identified greatest overall risk. • Spatial analysis revealed differences rural-urban and oceanfront-inland areas. [ABSTRACT FROM AUTHOR]

Digital elevation models (DEMs) derived from remote sensing data provide a valuable and consistent data source for mapping coastal flooding at local and global scales. Mapping of flood risk requires quantification of the error in DEM elevations and its effect on delineation of flood zones. The ASTER, SRTM, ALOS, and TanDEM-X (TDX) DEMs for the island of Hispaniola were examined by comparing them with GPS and LiDAR measurements. The comparisons were based on a series of error measures including root mean square error (RMSE) and absolute error at 90% quantile (LE90). When compared with >2000 GPS measurements with elevations below 7 m, RMSE and LE90 values for ASTER, SRTM, ALOS, TDX DEMs were 8.44 and 14.29, 3.82 and 5.85, 2.08 and 3.64, and 1.74 and 3.20 m, respectively. In contrast, RMSE and LE90 values for the same DEMs were 4.24 and 6.70, 4.81 and 7.16, 4.91 and 6.82, and 2.27 and 3.66 m when compared to DEMs from 150 km2 LiDAR data, which included elevations as high as 20 m. The expanded area with LiDAR coverage included additional types of land surface, resulting in differences in error measures. Comparison of RMSEs indicated that the filtering of TDX DEMs using four methods improved the accuracy of the estimates of ground elevation by 20–43%. DTMs generated by interpolating the ground pixels from a progressive morphological filter, using an empirical Bayesian kriging method, produced an RMSE of 1.06 m and LE90 of 1.73 m when compared to GPS measurements, and an RMSE of 1.30 m and LE90 of 2.02 m when compared to LiDAR data. Differences in inundation areas based on TDX and LiDAR DTMs were between −13% and −4% for scenarios of 3, 5, 10, and 15 m water level rise, a much narrower range than inundation differences between ASTER, SRTM, ALOS and LiDAR. The TDX DEMs deliver high resolution global DEMs with unprecedented elevation accuracy, hence, it is recommended for mapping coastal flood risk zones on a global scale, as well as at a local scale in developing countries where data with higher accuracy are unavailable. • Elevation accuracy of ASTER, SRTM, ALOS, and TDX DEMs for Hispaniola was assessed. • RTK GPS and LiDAR measurements were used as reference data for accuracy analysis. • TDX DEMs were filtered to remove building and tree pixels for generating DTMs. • The potential coastal inundation areas depicted by LiDAR and TDX DTMs were compared. • TDX DEMs provides the best global data source for mapping coastal flooding. [ABSTRACT FROM AUTHOR]

This research presents an operable zoning approach for phased evacuations adapted to disasters with spatio-temporal randomness. As a criterion for prioritizing evacuation order, evacuation risk is formulated by taking into consideration the estimated residual evacuation horizon associated with the characteristics of the disaster, the estimated time-dependent capacities of outbound lanes related to network supply, and the time-dependent evacuation demand of an evacuation unit. The modeling of the subzone determined for phased evacuation is based on rescue demand, the characteristics of the disaster, and network supply, and is labeled as a high-risk evacuation zone (HEZ). The range of HEZ features a time-evolving pattern in accordance with phased evacuation. The zone partition paradigm can be seamlessly applied to different types of disasters, especially those with high spatio-temporal randomness. It also provides a generalizable approach for subzone partitioning in phased evacuation by minimizing evacuation risk. The proposed approach is examined on numerical experiments through the road network of Xi'an, China, the results of which highlight its strength in increased adaptability to the dynamics of disaster impact and improved performance in evacuation operation. [ABSTRACT FROM AUTHOR]

At the eastern end of the 1957 Andreanof Islands, Alaska, USA, moment magnitude 8.6 earthquake rupture, Driftwood Bay (Umnak Island) and Stardust Bay (Sedanka Island) lie along presently locked and creeping parts of the Aleutian megathrust, respectively, based on satellite geodesy onshore. Both bays, located 200 km apart, face the Aleutian trench and harbor coastal evidence for tsunami inundation in 1957. Here we describe the evidence at Driftwood Bay, including eight sheets of landward-fining, normally-graded marine sand that extend up to 375 m inland and 23 m above mean tide level. Drift logs that corroborate historical accounts of 1957 tsunami runup on Umnak Island's Pacific coast overlie the youngest sand sheet, which 137Cs activity shows was deposited in the decade before 1963. The older sand sheets probably record tsunamis prior to 1957 because an emergent coastal terrace lacks evidence for storm-wave erosion and overwash since ca. 2 ka. Comparisons of the Driftwood Bay and Stardust Bay tsunami histories suggest that at least twice in the past 1700 years inundation occurred at one site but not the other. In contrast, Bayesian age-depth modeling suggests that the two bays may record five tsunamis like the 1957 tsunami, generated by earthquake ruptures that spanned the presently locked and creeping parts of the Aleutian megathrust. However, serial tsunamis occurring within days to centuries cannot be precluded. Our findings imply 164-257-year recurrence intervals for large eastern Aleutian tsunamis and challenge the notion that creeping parts of the megathrust, inferred from geodesy onshore, pose lower earthquake and tsunami hazards than locked areas. [ABSTRACT FROM AUTHOR]

This study focused on flood damage assessment for future floods under the impact of climate change. Four river basins of Southeast Asia were selected for the study. They included the Pampanga River Basin (PRB) in the Philippines, the Solo River Basin (SRB) in Indonesia, the Lower Mekong River Basin (LMRB) in Cambodia and Vietnam, and the Chao Phraya River Basin (CPRB) in Thailand. Flood damage to rice crops was assessed by flood damage functions considering flood depth and duration and the growth stage of rice plants. Flood characteristics such as flood depth, duration, and distribution were computed using the rainfall–runoff–inundation model to assess flood hazards under the present and future climatic conditions produced by MRI-AGCM3.2S. The damage assessment methodology for rice crops employed in this study was verified using data on past flood events. Then, flood damage assessment was conducted for both the present climate (1979–2003) and future climate (2075–2099) conditions, using MRI-AGCM3.2S precipitation datasets. Flood damage was assessed for worst cases chosen from each climate period and for floods of 50- and 100-year return periods with different rainfall patterns chosen from each climate scenario. The results of flood hazard and damage assessment show that the flood inundation area for a 100-year flood may increase in the future by 20% in PRB; by 66% in SRB; by 27% in LMRB; and by 27% in CPRB. The flood damage area of paddy fields for a 100-year flood may also increase in the future by 16% in PRB; by 55% in SRB; by 23% in LMRB; and by 13% in CPRB. [ABSTRACT FROM AUTHOR]

Tsunamigenic earthquakes have been known for their near and far field catastrophic impacts on coastal areas near oceanic ridges and trenches, as well as near tectonic faults in closed and semienclosed seas. Not all regions of oceanic ridges and trenches are tsunamigenic earthquake zones, but knowledge of the weighted sum of released earthquake energy and of the Gutenberg-Richter relation of the 'a' and 'b' parameters are needed to better identify them as to their potential for tsunami generation. The present analysis was undertaken in order to better identify tsunamigenic zones near oceanic ridges and trenches in the Mid-Atlantic, in the Pacific, in Chile, in Japan, near the Aleutians and along the Peru-Chile trench. The weighted sum of earthquake energy released and of the Gutenberg-Richter relation parameters were evaluated to identify tsunamigenic earthquake zones along these locations. The present analysis of the Gutenberg-Richter relation of the 'a' and 'b' parameters indicates that tsunamigenic earthquakes do not occur frequently along the Aleutian Trench, although the historic record supports that destructive tsunamis have occurred along this region in the past. Of the oceanic ridges, the results of the present analysis indicate that the Mid-Atlantic Ridge is the most active tsunamigenic zone, while of all the oceanic trenches, the Japan Trench is the most active. [ABSTRACT FROM AUTHOR]

Nowadays, water inundation often occurs in some areas in Cimahi. One of the highest inundation occurred on Jenderal H. Amir Machmud street with a depth of 100 cm with the receding time 1 - 2 hours. This condition causes a very high level of congestion, so it can cut access from Bandung to Cimahi. In addition, of course, this condition can cause damage to the road itself. Using a drainage cross-section data from Cimahi government and field measurement, rainfall data, topographic map, and land use data the existing drainage capacity can be calculated by manual and HEC-RAS. Based on the result of manual calculation, there is total debit in drainage channel on 2 year return period is 2.86 m3/sec, 5 year return period is 3.59 m3/sec, and a 10 year return period is 4.08 m3/sec with the existing channel debit is 2.02 m3/sec so that cause the water overflows from the channel. The Cilember River flows with a large discharge 2 years period is 59.64 m3/sec, a 5 year return period is 93.74 m3/sec, and 10 years 118.30 m3/sec crossing Amir Machmud Street affecting high inundation at the site of the review. To solve the problem, some models of solution have been made in the form of new box culvert drainage channel planning with the smallest dimension is 2 × 2 m and biggest dimension is 3 × 3 m. Meanwhile, to handle the overflow of water from Cilember River planned 2 pieces of culverts with dimensions 2.5 × 2.5 m. [ABSTRACT FROM AUTHOR]

The 1783 Scilla tsunami, induced by a coastal landslide occurring during an intense seismic sequence in Calabria (South Italy), was one of the most lethal ever observed in Italy. It caused more than 1500 fatalities, most of which on the 10 beach close to the town where people gathered to escape earthquake shaking. In this paper, complementing a previous work (Zaniboni et al., 2016) focusing on the very local tsunami effects in the town of Scilla, we study the tsunami impact on the Calabria and Sicily coasts out of Scilla. To this purpose we take into account the same landslide geometry considered in the previous study and perform three tsunami simulations, one embracing a larger region with a 50-m computational grid, and two covering the specific area of Capo Peloro, in Sicily, facing Scilla on the western side of the Messina Straits, with even 15 higher resolution (10 m mesh). Numerical results show a very good agreement with the historical observations in Capo Peloro. Moreover, the resulting global tsunami inundation pattern provides a useful hint for tsunami hazard assessment in the Messina Straits area, which is known to be one of the most exposed to tsunami threat in Italy and in the Mediterranean Sea. [ABSTRACT FROM AUTHOR]

Flood maps are needed for emergency response, research, and planning. The Height Above Nearest Drainage (HAND) technique is a low-complexity, terrain-based approach for inundation mapping from elevation, discharge-height relationship, and streamflow data. The recent operational capacities of the NOAA National Water Model (NWM) and pre-processed HAND products from the University of Texas offer an operational framework for real-time and forecast flood mapping across the United States. This paper offers the first detailed evaluation of the coupled NWM-HAND approach by comparing NWM-HAND simulations to a database of remotely sensed flood maps. These comparisons are made both quantitatively and through a detailed evaluation of selected results. The results show that NWM-HAND performs well in the majority of cases with 70 % of the calculated flood maps yielding an agreement of 80 % or better with the remote sensing observations. Persistent inaccuracies occur in lower-order reaches, regions of low relief, and when the NWM misses substantially either in magnitude or timing. [ABSTRACT FROM AUTHOR]

Highlights • EIM was proposed for urban flood hazard mapping at the large catchment scale. • SWMM model was introduced in floodwater generation process. • Floodwater spreading was based on topological relation of depression outlets. • Floodwater from lower depression elements was considered in EIM. • The performance of EIM was validated in terms of inundation locations and depths. Abstract Urban flooding occurs frequently in the world and urban hydrological models are widely applied in urban flood management and disaster mitigation. In this study, an enhanced inundation method (EIM) for urban flood hazard mapping at the large catchment scale is proposed. EIM can be easily coupled with urban hydrological models and the coupled framework can consider both source flooding and non-source flooding in floodwater generation. In EIM, the floodwater spreading order in the positive process is based on the topological relationship between depression outlets; the floodwater from lower depression elements is considered as a feedback process. These improvements make this proposed method suitable for inundation estimation in large urban catchments. Dahongmen (DHM) catchment in Beijing, China was selected as the case study area to illustrate the applicability of the proposed method. Historical inundation records during one heavy storm were applied to test the performance of the method. EIM is compared with USISM (urban storm-inundation simulation method) on the flood hazard map in the DHM catchment, which reveals the effectiveness of the improvements. The results show that all inundation locations are successfully identified by EIM and are distributed in flooding areas (water depth greater than 0.15 m) in the catchment. The average relative error of simulated inundation depths is 15%, which indicates that EIM can successfully simulate flooding scopes and depths in the study area. The results revealed that EIM can be a valuable tool for mapping urban flood hazards at the large catchment scale based on GIS techniques. [ABSTRACT FROM AUTHOR]

Highlights • A multi-level framework for stress testing port infrastructures is presented. • Regulatory requirements do not exist, and risk objectives are based on judgments. • Critical components are identified, and recommendations are provided. • The results depend on the stress test level, analysis approach, and risk metrics. • The systemic risk for the tsunami hazard is very low compared to seismic risk. Abstract An engineering risk-based methodology for stress testing critical infrastructures is introduced and applied to the port of Thessaloniki in Greece exposed to seismic, geotechnical and tsunami hazards. The methodology workflow consists of four phases: Pre-Assessment, Assessment, Decision and Report phase. In the pre-assessment phase, all the necessary information is collected and archived. For the pilot study, the inventory includes the main port components namely buildings, waterfronts, cranes and the electric power system. Generic or site-specific fragility models are used for all exposed elements and considered hazards. Risk metrics and objectives are defined related to the functionality of the system and the structural losses. In the first level of the assessment phase, the performance of each component is evaluated using a risk-based approach. Then, a system level probabilistic risk analysis is conducted separately for earthquake and tsunami hazards. A complementary scenario-based risk analysis is carried out aiming to investigate the impact of site-specific response and extreme seismic events to the performance of the port. In the Decision phase, the results are compared with predefined objectives to decide whether the infrastructure passes, partly passes or fails the test. Guidelines and strategies to improve the performance and resilience of the port are summarized. [ABSTRACT FROM AUTHOR]

This study is aimed at producing an improved ranking method by coupling the technique for the order of preference by similarity to ideal solution (TOPSIS) and Mahalanobis distance (MD) to prioritize the districts of Golestan Province, northeast of Iran, with respect to the prevailed natural hazards. The main idea of this work is underpinned by introducing a method that is: (1) in accordance with holistic thinking by engaging different threatening natural hazards in order to rank different threatened targets and (2) harmonized by the probabilistic context of the natural hazards. Therefore, maximum entropy (MaxEnt), a well-known data mining model, was used to model the spatial pattern of flood inundation and landslide occurrence over the study area. The area under the receiver operating characteristic (AUROC) was used to assess the goodness of fit and prediction power of the used models. As a result, the MaxEnt model showed an outstanding predictive performance with the AUROC values of 0.889 and 0.903 for landslide and flood inundation modelling, respectively. Afterwards, the revised universal soil loss equation (RUSLE) was employed to model soil erosion. This model successfully estimated the average soil loss of the study area with a value of about 33 ton/ha/yr which is in the range reported by provincial natural resources organization (10-35 ton/ha/yr). Results revealed that highly susceptible areas to the landslide, flood inundation, and water erosion potentially account for about 11, 9.6, and 6.6% of the Golestan Province surface area. Lastly, the TOPSIS–MD, TOPSIS, and Simple Additive Weight (SAW) methods were used to prioritize the districts of the Golestan Province with respect to all three susceptibility maps. As a result, TOPSIS–MD was chosen as the well-performing ranking method for further environmental managerial actions due mainly to considering the strong correlations among the criteria. According to TOPSIS–MD results, Minoodasht, Ramian, and Gorgan districts were recognized as the most threatened districts, while Gomishan, Aq Qala, and Gonbad-e Kavous districts are located at a safe zone with respect to the studied susceptibility indices. The proposed TOPSIS–MD framework merits more studies and is applicable to any multi-criteria decision-making issue in any branch of science. [ABSTRACT FROM AUTHOR]

Tsunamis can have severe impacts on society. In addition to casualties and damage to buildings, they can also damage and disrupt critical infrastructure. To support effective risk management, it is important to understand the possible extent, severity and duration of these impacts. While impacts on buildings and casualty estimations are relatively well developed for tsunamis, critical infrastructure impact models are either not available or lack accurate vulnerability information. This paper addresses these issues by reviewing global tsunami impacts to critical infrastructure to develop a semi-quantitative tsunami damage matrix for critical infrastructure components and systems. One potential application of the damage matrix is demonstrated within an impact assessment process for Christchurch, New Zealand. The impact assessment determines asset damage likelihood for energy, water, telecommunication and transportation assets from a large tsunami inundation scenario. Consistent with observations from previous international tsunamis, above-ground assets and buried storm water pipe networks in Christchurch were found to perform poorly, while buried potable and waste water pipe networks were less impacted. This process provides a simple, but widely applicable, impact assessment approach which further studies can build on. Future research should focus on developing quantitative probabilistic tsunami vulnerability models for critical infrastructure that implement multiple asset standards and hazard intensity measures, and better account for uncertainty. [ABSTRACT FROM AUTHOR]

Structural vulnerability due to tsunami loading can be characterized by a family of fragility curves, which are expressed as lognormal cumulative distributions of the conditional probabilities of reaching or exceeding various damage states for given values of the demand parameter, generally inundation depth. Such curves can easily be obtained from field surveys. However, what is required for risk analyses is total damage. This research presents a method of obtaining mean damage curves from fragility functions in the literature, using cost coefficients associated with each of four damage states. The curves are obtained for timber, masonry and reinforced concrete single-storey structures. They could also be fitted very well with negative power law expressions having two parameters, and quite well with negative exponential functions having just a single parameter (based on construction material) and the single independent variable of inundation depth. The damage curves can also be used to present the relative vulnerability of one construction material with respect to another; this could reduce the variability associated with different locations. The relative damage ratios for the different construction materials were found to be strongly dependent on inundation depth. Although there are large differences among construction materials at low depths, such differences disappear at depths of 6–10 m. Similarly, the effects of shielding and debris on damage were also found to be dependent on inundation depth. The results of this work can be used to introduce coupling effects into empirical relative vulnerability models that seek to incorporate many factors independently. [ABSTRACT FROM AUTHOR]

On March 11, 2011, a magnitude MW 9.0 thrust earthquake ruptured the Japan Trench along the northwest coast of Honshu and generated a tsunami that killed 15,894 people, left 2585 missing (as of March 2017) and destroyed more than 130,000 houses. The purpose of this paper is to review the current status and scope of tsunami recovery in the Tohoku region, focusing on investments in structural protection measures as well as extensive implementation of non-structural "managed retreat." Japan's response to the 2011 tsunami contrasts with approaches to disaster management in the USA and elsewhere in the world. New structural protections built in Japan since 2011 include a massive concrete-lined tsunami barrier system, stretching > 400 km of coast, at a cost of at least $8 billion. Managed retreat is a relatively new area of research and risk management focusing on withdrawal of infrastructure and population from at-risk areas. Japan's post-tsunami disaster response may represent the single largest case of disaster-related managed retreat in recent world history. Approximately 145,000 homes, including whole new towns, are being built outside the tsunami hazard zone. Disaster managers worldwide should look to Japan for lessons learned from the investment and efforts since 2011. [ABSTRACT FROM AUTHOR]