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Chile, recognized as one of the world's most earthquake-prone nations, has gained valuable insights from significant earthquakes, such as those in 1985 and 2010, which have influenced updates to the nation's design codes. Although Chile's seismic design approach has been largely effective in recent earthquakes and demonstrated an "operational" performance level in most structures, performance-based design (PBD) methods have not yet been officially incorporated as valid approaches in the Chilean seismic design codes for buildings. However, in 2017, the Chilean Association on Seismology and Earthquake Engineering (ACHISINA) introduced a PBD approach, primarily for verification purposes, based on the Los Angeles Tall Buildings Structural Design Council (LATBSDC) framework. In this work, firstly, we provide an overview of Chile's PBD methodology, focusing on the thresholds for various performance levels. These levels are established through experimental and numerical analysis, correlating performance with permissible damage levels. The second part of the paper examines the seismic performance of a residential building, designed before the 2010 Maule earthquake and subsequently damaged, using Chile's PBD guidelines. This case study highlights the implementation and effectiveness of PBD for assessing seismic resilience in Chilean structures. [ABSTRACT FROM AUTHOR]

The construction of fuel moisture content (FMC) maps, as well as temperature, terrain topography, and wind speed maps, are essential for the development of fire susceptibility models in forested areas. Moisture distribution in tree canopies requires exploration and a three-dimensional representation. This paper presents the construction of FMC maps expressed as vegetation indices (VIs) in a point cloud. Multispectral images were captured by a camera mounted on an unmanned aerial vehicle to create the point cloud. VIs were estimated in the points that belonged to the forest canopy. To classify the canopy points, we a combination of filtering of ground points and thresholding of VIs was evaluated. On such canopy points, random forest (RF), kernel ridge regression (KRR), and Gaussian process retrieval (GPR) regressors were investigated to estimate twelve VIs related to FMC. The input set of the models consisted of the points representing five wavelengths provided by the multispectral camera. The ground truth of VIs was obtained using a spectrometer. The study area was a 1 ha forest of Pinus radiata in the Maule Region, Chile. The results demonstrated that combining ground filtering and VIs thresholding for canopy points segmentation achieved a precision of 93.27%, recall of 95.65%, F1 score of 90.12%, and accuracy of 87.82%. Furthermore, the recovery of the VIs using GPR achieved a root mean square error of 0.175 and a coefficient of determination of 0.18. According to the correlation coefficient, GPR was able to recover eleven of the twelve VIs, KRR recovered three, and RF failed to recover any. [Display omitted] • A sensitivity analysis was performed to find a vegetation index threshold. • Vegetation indices and geometric soil filtering improves point cloud segmentation. • Gaussian process retrieval estimated eleven of the twelve vegetation indices. • A vegetation index map was constructed from photogrammetry and machine learning. [ABSTRACT FROM AUTHOR]

Catastrophic megaearthquakes (M > 8) occurring in the subduction zones are among the most devastating hazards on the planet. In this paper we discuss the seismic cycles of the megathrust earthquakes and propose a blockwise geomechanical model explaining certain features of the stress-deformation cycle revealed in recent decades from seismological and satellite geodesy (GNSS) observations. Starting with an overview of the so-called keyboard model of the seismic cycle by L. Lobkovsky, we outline mathematical formalism describing the motion of seismogenic block system assuming viscous rheology beneath and between the neighboring elastic blocks sitting on top of the subducting slab. By summarizing the GNSS-based evidence from our previous studies concerning the transient motions associated with the 2006–2007 Simushir earthquakes, 2010 Maule earthquake, and 2011 Tohoku earthquake, we demonstrate that those data support the keyboard model and reveal specific effect of the postseismic oceanward motion. However, since the seismogenic blocks in subduction systems are mostly located offshore, the direct analysis of GNSS-measured displacements and velocities is hardly possible in terms of the original keyboard model. Hence, the generalized two-segment keyboard model is introduced, containing both frontal offshore blocks and rear onshore blocks, which allows for direct interpretation of the onshore-collected GNSS data. We present a numerical computation scheme and a series of simulated data, which exhibits the consistency with measured motions and enables estimating the seismic cycle characteristics, important for the long-term earthquake forecasting. [ABSTRACT FROM AUTHOR]

Several magnetic measurements and theoretical developments from different research groups have shown certain relationships with worldwide geological processes. Secular variation in geomagnetic cutoff rigidity, magnetic frequencies, or magnetic anomalies have been linked with spatial properties of active convergent tectonic margins or earthquake occurrences during recent years. These include the rise in similar fundamental frequencies in the range of microhertz before the Maule 2010, Tōhoku 2011, and Sumatra–Andaman 2004 earthquakes and the dramatic rise in the cumulative number of magnetic anomalous peaks before several earthquakes such as Nepal 2015 and Mexico (Puebla) 2017. Currently, all of these measurements have been physically explained by the microcrack generation due to uniaxial stress change in rock experiments. The basic physics of these experiments have been used to describe the lithospheric behavior in the context of the seismo-electromagnetic theory. Due to the dramatic increase in experimental evidence, physical mechanisms, and the theoretical framework, this paper analyzes vertical magnetic behavior close to the three latest main earthquakes in Chile: Maule 2010 (Mw 8.8), Iquique 2014 (Mw 8.2), and Illapel 2015 (Mw 8.3). The fast Fourier transform (FFT), wavelet transform, and daily cumulative number of anomalies methods were used during quiet space weather time during 1 year before and after each earthquake in order to filter space influence. The FFT method confirms the rise in the power spectral density in the millihertz range 1 month before each earthquake, which decreases to lower values some months after earthquake occurrence. The cumulative anomaly method exhibited an increase prior to each Chilean earthquake (50–90 d prior to earthquakes) similar to those found for Nepal 2015 and Mexico 2017. The wavelet analyses also show similar properties to FFT analysis. However, the lack of physics-based constraints in the wavelet analysis does not allow conclusions that are as strong as those made by FFT and cumulative methods. By using these results and previous research, it could be stated that these magnetic features could give seismic information about impending events. Additionally, these results could be related to the lithosphere–atmosphere–ionosphere coupling (LAIC effect) and the growth of microcracks and electrification in rocks described by the seismo-electromagnetic theory. [ABSTRACT FROM AUTHOR]

Hibiscus cannabinus (kenaf) is well known as a source for textile fibers and as an alternate source for cellulosic fibers for paper and pulp industry. Formation of reaction xylem alters the chemical properties of fibers, which may affect its uses. To the best of our knowledge, there are no reports on the occurrence of reaction xylem in kenaf. The present study examines reaction xylem (i.e. tension wood and its opposite side) formed in response to bending of stems in Kenaf by anatomical, histochemical and biochemical methods. The reaction xylem found on the upper side of leaning stems showed an eccentric growth pattern, thin walls, shorter and wider fibers without gelatinous layer, decrease of vessel or ray density as compared to wood formed on opposite sides. Histochemical localization of lignin using Weisner reaction and Maule's test indicated presence of more syringyl units in the fiber wall of tension wood. Gravimetric quantification of cell wall polymers showed relatively more amount of holocellulose and hemicellulose in tension wood (69 and 46 %, respectively) compared to those of opposite wood (63 and 42 %, respectively). There was no significant difference noticed in the klason lignin content between opposite (17.4 %) and tension wood (16.7 %). Lignin characterization by the thioacidolysis method revealed that the tension wood lignin in kenaf was composed of more amount of syringyl and p-hydroxyphenyl monomers compared to that of opposite side wood. This analysis also suggests that the tension wood lignin is rich in β-aryl ether linkages in syringyl units resulting in high S/G ratio. [ABSTRACT FROM AUTHOR]

Several magnetic measurements and theoretical development from different research groups have shown certain relationship with worldwide geological processes. Secular variation of geomagnetic cut off rigidity, magnetic frequencies, or magnetic anomalies have been linked with spatial properties of active convergent tectonic margin or earthquakes occurrences during recent years. These include the rise of similar fundamental frequencies in the range of micro hertz before Maule 2010, Japan 2011, and Sumatra 2004 earthquakes and the dramatic rise of the cumulative number of magnetic anomalous peaks before several earthquakes as Nepal 2015 and Mexico 2017, among others. Currently, all of these measurements have been physically explained by the microcrack generation due uniaxial stress change in rock experiments. The basic physics of these experiments have been used to describe the lithospheric behavior in the context of the seismo-electromagnetic theory. Due to the dramatic increase in experimental evidence, physical mechanism and theoretical framework, this paper analyses vertical magnetic behavior close to the latest three main earthquakes in Chile: Maule 2010 (Mw8.8), Iquique 2014 (Mw8.2), and Illapel 2015 (Mw8.3). The FFT, Wavelet transform and daily cumulative number of anomalies methods were used during quiet space weather time during one year before and after each earthquake in order to filter space influence. FFT Method confirm the raise of power spectral density in mHz range before one month each earthquake, which decrease to lower values after some months after earthquake occurrence. The cumulative anomalies method exhibited and increase previous to each Chilean earthquake (50-90 days prior earthquakes) similar to those found for Nepal 2015 and Mexico 2017. The wavelet analyses also show as similar properties as FFT analysis. However, the lack of physics-based constrain in the wavelet analysis do not allow conclusion as strong as FFT and cumulative methods. By using these results and previous research, it could be stated that these magnetic features could give seismic information from impending events. Additionally, these results could be related to the Lithosphere-Atmosphere-Ionosphere coupling (LAIC effect) and the growth of micro cracks and electrification in rocks described by the seismo-electromagnetic theory. [ABSTRACT FROM AUTHOR]

Purpose: This paper examines disaster capitalism in Chile, that is, the relationships between disasters and neoliberalism. It looks at two post-disaster dimensions: disasters as windows of opportunity to introduce political reforms and disasters as occasions for the corporate class to capitalize on such disasters. Design/methodology/approach: Two indices, disaster capitalism (DC) and post-disaster private involvement (PDPI), are proposed for cross-case analysis. They are based on legal records, institutional reports and economic data. The DC assesses the introduction of reforms following disasters, while PDPI evaluates the share of public-private funding used for recovery. Both indices are applied here to two disasters in Chile: the 2010 Maule earthquake, and the 2008 Chaitén volcanic eruption. Findings: Results show that the highly neoliberal Chilean context leaves limited space for new neoliberal reforms. Although recovery is implemented predominantly through the private sector, the state still assumes greater responsibility for recovery costs. Results also detect poor levels of participation from the private sector in accounting their efforts and making them publicly available. Likewise, the research suggests that neoliberal reforms become more likely after disasters. However, the preexisting politico-economic context matters. Finally, there is clearly a need for data systematization in post-disaster recovery. Originality/value: In the Chilean context, the indices proved beneficial as a strategy for data collection and a method for scrutinizing the implications of neoliberal policy implemented in the wake of disasters, as well as in evaluating the role of the corporate class during recovery. [ABSTRACT FROM AUTHOR]

More than half of all the people in the world now live in dense urban centres. The rapid expansion of cities, particularly in low-income nations, has enabled the economic and social development of millions of people. However, many of these cities are located near active tectonic faults that have not produced an earthquake in recent memory, raising the risk of losing hard-earned progress through a devastating earthquake. In this paper we explore the possible impact that earthquakes can have on the city of Santiago in Chile from various potential near-field and distant earthquake sources. We use high-resolution stereo satellite imagery and imagery-derived digital elevation models to accurately map the trace of the San Ramón Fault, a recently recognised active fault located along the eastern margins of the city. We use scenario-based seismic-risk analysis to compare and contrast the estimated damage and losses to the city from several potential earthquake sources and one past event, comprising (i) rupture of the San Ramón Fault, (ii) a hypothesised buried shallow fault beneath the centre of the city, (iii) a deep intra-slab fault, and (iv) the 2010 Mw 8.8 Maule earthquake. We find that there is a strong magnitude–distance trade-off in terms of damage and losses to the city, with smaller magnitude earthquakes in the magnitude range of 6–7.5 on more local faults producing 9 to 17 times more damage to the city and estimated fatalities compared to the great magnitude 8+ earthquakes located offshore in the subduction zone. Our calculations for this part of Chile show that unreinforced-masonry structures are the most vulnerable to these types of earthquake shaking. We identify particularly vulnerable districts, such as Ñuñoa, Santiago, and Providencia, where targeted retrofitting campaigns would be most effective at reducing potential economic and human losses. Due to the potency of near-field earthquake sources demonstrated here, our work highlights the importance of also identifying and considering proximal minor active faults for cities in seismic zones globally in addition to the more major and distant large fault zones that are typically focussed on in the assessment of hazard. [ABSTRACT FROM AUTHOR]

The time at which climate change signal can be clearly distinguished from noise is known as time of emergence (ToE) and is typically detected by a general circulation model (GCM) signal-to-noise ratio exceeding a certain threshold. ToE is commonly estimated at large scales from GCMs, although management decisions and adaptation strategies are implemented locally. This paper proposes a methodology to estimate ToE for both precipitation and temperature at local scales (i.e., river basin). The methodology considers local climatic conditions and unbiased GCM projections to estimate ToE by using the statistical power to find when the climate significantly differs from the historical one. The method suggests that ToE for temperature already occurred in three Chilean basins (Limarí, Maipo, and Maule). However, in terms of precipitation, an earlier ToE is clearly identified for the Maule basin, indicating that risk assessment and adaptation measures should be implemented first in this basin. [ABSTRACT FROM AUTHOR]

Natural hazards such as earthquakes, floods, or wildfires pose a serious threat to road infrastructure. Especially in emergency situations, the society depends on the road infrastructure to maintain its functionality in terms of evacuation and accessibility to emergency facilities. In this paper, we develop a generic, multi-scale concept to analyze the accessibility to emergency facilities in critical road infrastructure for natural disaster scenarios. We follow a modular approach: The basic module evaluates the accessibility of emergency facilities by calculating an accessibility index. Other modules enable the calculation of a grid-based index and the generation of a degraded network based on a natural disaster scenario. OpenStreetMap serves as a free-to-use and worldwide available database for the road network and the emergency facility location. The concept is applied exemplarily for two wildfire scenarios of different geographic scales: the January 2017 Wildfires in the BioBío and Maule region located in central Chile and the June 2017 Wildfires in central Portugal. An impact analysis of the wildfires on the accessibility of emergency facilities is performed and evaluated. As a result, the concept provides a valuable and data-sparse decision aid tool for regional planners and disaster control. It can be used in different stages of the disaster risk management cycle. In the mitigation and preparation phase, places with poor accessibility can be identified. In the short-term response phase after a disaster, the quick identification of critical and disconnected road network parts assists disaster control in planning a possible reaction strategy. [ABSTRACT FROM AUTHOR]

More than half of all the people in the world now live in dense urban centres. The rapid expansion of cities, particularly in low-income nations, has enabled the economic and social development of millions of people. However, many of these cities are located near active tectonic faults that have not produced an earthquake in recent memory, raising the risk of losing the hard-earned progress through a devastating earthquake. In this paper we explore the possible impact that earthquakes can pose to the city of Santiago in Chile from various potential near-field and distant earthquake sources. We use high resolution stereo satellite imagery and derived digital elevation models to accurately map the trace of the San Ramón Fault, a recently recognised active fault located along the eastern margins of the city. We use scenario based seismic risk analysis to compare and contrast the estimated damage and losses to the city from several potential earthquake sources and one past event, comprising (i) rupture of the San Ramón Fault, (ii) a hypothesised buried shallow fault beneath the centre of the city, (iii) a deep intra-slab fault, and (iv) the 2010 Mw 8.8 Maule earthquake. We find that there is a strong magnitude-distance trade-off in terms of damage and losses to the city, with smaller magnitude earthquakes on more local faults, in the magnitude range 6–7.5, producing 9 to 17 times more damage to the city and estimated fatalities compared to the great magnitude 8+ earthquakes located offshore on the subduction zone. Our calculations for this part of Chile show that unreinforced masonry structures are the most vulnerable to these types of earthquake shaking. We identify particularly vulnerable districts, such as Ñuñoa, Santiago and Macul, where targeted retrofitting campaigns would be most effective at reducing potential economic and human losses. Due to the potency of near-field earthquake sources demonstrated here, our work highlights the importance of also identifying and considering proximal minor active faults for cities in seismic zones globally, in addition to the more major distant large fault zones that are typically focused on in the assessment of hazard. [ABSTRACT FROM AUTHOR]

• Six obsidian sources increased their use in the Late Holocene in north Patagonia. • The closer source to Diamante Valley, is the least used. • The best quality source, Las Cargas, was the most used across the Late Holocene. • Obsidian helped to minimize risk in the occupation of high elevation locations. • Obsidian exchange routes may find a pattern in least cost path analysis results. • Exchange of obsidian followed routes through High elevations villages to sources. In this paper we explore obsidian conveyance in the Diamante Valley, in northwestern Patagonia, Argentina. Obsidian is the third most-common toolstone used in the Diamante Valley after basalts and local cryptocrystallines. Obsidian artifacts are predominantly projectile points and bifaces, with few cores and early-stage reduction debris. To explain these patterns, we conducted XRF sourcing and technological analysis of 177 obsidian artifacts collected there. We also conducted a GIS-based least cost path analysis to assess the costs of conveying obsidian from sources to sites in the Diamante watershed. We found that hunter-gatherers used Las Cargas as the principal obsidian source, followed by Maule 1 and 2, El Peceño, and Coche Quemado. The nearest source, Laguna del Diamante, was the least used. These data, combined with an analysis of the ways cores, formed tools, and debitage types were conveyed and ultimately deposited at sites in the Diamante watershed, suggest a late Holocene pattern of highland-oriented indirect access, implying highland village sites likely served as nodes in a regional and extraregional exchange network focused not only on obsidian but also on other goods, information, and social obligations. [ABSTRACT FROM AUTHOR]

• A new self-centering shear key geometry is proposed that eliminates residual displacements of the superstructure, using only the structure's own weight, geometry and conventional bearing pads to generate the required restoring force. • The proposed solution is simply a change in the kinematics of the bridge allowing superstructure's self-centering. • The new self-centering technique is used to analyze a typical Chilean bridge using a set of records classified by soil types, considering the three translational components of the ground motion components. The results indicate that the technique is feasible, but care needs to be taken in accounting for an increase in forces in the substructure. • The proposed shear key concept does not need additional devices such seismic isolators or energy dissipation elements. With a simple change of the geometry, the elimination of the residual displacements ensures the superstructure's self-centering behavior. Shear keys are elements in bridges designed to prevent or limit transverse unseating, rotation, and/or collapse of the superstructure responding to strong-intensity earthquake input ground motion, as well as to absorb breaking and various self equilibrating forces. During the 2010 Maule earthquake, Chile's highway infrastructure was seriously impacted. Shear key failures were endemic and did not function as intended. As a result, some bridges experienced partial or complete collapse. Even when the shear keys appeared to have worked, the superstructure exhibited large offsets, which required expensive repairs. An expensive retrofit of undamaged bridges was also carried out as a result of the inadequate response of the bridge infrastructure. This paper addresses the behavioral issues of bridges designed incorporating conventional shear keys and proposes an innovative self-centering concept that eliminates residual displacements in the superstructure. The self-centering shear key concept, as it will be termed here, makes use of the bridge self-weight as a restoring force to ensure self-centering. This concept proposal takes advantage of the kinematics of the bridge. The self-centering shear key concept was validated for a typical Chilean bridge via an extensive study that made use of nonlinear time history analyses. The results indicate that the increase in seismic demand on the substructure is small enough to maintain the bridge base structure in the elastic range while eliminating any residual displacements in the superstructure. [ABSTRACT FROM AUTHOR]

A very large coseismic displacement (≈304 cm) was recorded at the city of Concepción during the moment magnitude (Mw) 8·8 Offshore Maule, Chile earthquake of 27 February 2010. The Alto Rio building, a 15-storey reinforced concrete structure with two underground levels, experienced a global overturning collapse, resulting in the death of eight of its occupants. Ever since, a lingering question has preoccupied the minds of structural engineers and earth scientists: Did the large coseismic displacement cause the overturning collapse of this building? The answer based on the analyses provided in this paper is no. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

• Inelastic finite element model of a reinforced concrete wall building slice. • Earthquake and tsunami loadings in sequence applied to the building model. • The tsunami capacity is sensitive to the Froude number. • The tsunami capacity is only affected by severe previous earthquake damage. This paper investigates the behavior of a typical Chilean reinforced concrete wall building under sequential earthquake and tsunami actions using a double pushover analysis approach. A real concrete wall structure that was damaged after the M w = 8.8 2010 Maule earthquake is considered as a case study building and a simplified nonlinear finite element model of a fictitious slice of the building is subjected to earthquake and tsunami loading in sequence. The analysis of the building under these loadings consists of three stages: the structure is first subjected to seismic loading by means of a pushover analysis until a specific damage state is reached; then a pushover with the same load pattern but in the opposite direction is applied until the shear at the base is zero; and finally, the building is subjected to tsunami loading by means of a variable depth pushover analysis until the maximum capacity is reached. Different tsunami load cases are considered in this study, varying the Froude number and the direction of the tsunami loading. The results show that the tsunami response of the building is mainly dependent on the Froude number of the tsunami flow; however, when the seismic damage is severe, the tsunami capacity of the building is found to be reduced. This is more likely to occur when the effect of the tsunami increases the damage previously induced by the earthquake in the same direction. [ABSTRACT FROM AUTHOR]

Average speed is crucial for calculating link travel time to find the fastest path in a road network. However, readily available data sources like OpenStreetMap (OSM) often lack information about the average speed of a road. However, OSM contains other road information which enables an estimation of average speed in rural regions. In this paper, we develop a Fuzzy Framework for Speed Estimation (Fuzzy-FSE) that employs fuzzy control to estimate average speed based on the parameters road class, road slope, road surface and link length. The OSM road network and, optionally, a digital elevation model (DEM) serve as free-to-use and worldwide available input data. The Fuzzy-FSE consists of two parts: (a) a rule and knowledge base which decides on the output membership functions and (b) multiple Fuzzy Control Systems which calculate the output average speeds. The Fuzzy-FSE is applied exemplary and evaluated for the BioBío and Maule region in central Chile and for the north of New South Wales in Australia. Results demonstrate that, even using only OSM data, the Fuzzy-FSE performs better than existing methods such as fixed speed profiles. Compared to these methods, the Fuzzy-FSE improves the speed estimation between 2% to 12%. In future work, we will investigate the potential of data-driven machine learning methods to estimate average speed. The applied datasets and the source code of the Fuzzy-FSE are available via GitHub. [ABSTRACT FROM AUTHOR]