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The September 28, 2018 earthquake and tsunami, which occurred north of Palu City, Indonesia, attracted widespread interest from the scientific community due to the unusually large tsunami that occurred after a strike-slip earthquake with a relatively small moment magnitude (MW = 7.5). To understand the structural performance of buildings and infrastructure under hydrodynamic loads and their associated effects, the authors conducted field surveys in Palu City. Light wooden frame constructions and masonry infill walls were common in the area, some of which were severely damaged by the earthquake and tsunami. Reinforced concrete structures remained predominantly intact, although they suffered soil-related issues such as scour around rigid building members. Local structural failures caused by the loss of supporting soil were also observed during the field survey, resulting in an overall reduction in the stability of the inspected structures. Based on the observations made, knowledge gaps and research needs concerning coastal and structural scouring are discussed. These are tied into the latest community research activities and put in the context of a published ASCE standard chapter that discusses tsunami design. [ABSTRACT FROM AUTHOR]

In 2018, Lombok island, Indonesia, was hit by a series of destructive earthquakes that caused thousands of casualties and widespread material damage. In response to those events, a field survey was conducted along the coast of Lombok aiming at collecting data about disaster preparedness and awareness of local inhabitants regarding natural disasters, with a focus on tsunami events. During the survey, the authors interviewed witnesses of small tsunami waves that were generated by the 2018 earthquakes. The work described here encompasses the authors' field observations, which helped ascertain the occurrence of small-scale tsunamis, and the analysis of data collected via unstructured interviews and a limited questionnaire survey. Attention is drawn to the potential value added by recording small-scale tsunamis for future research, and some insights into what priorities should be set for future disaster risk management in Lombok are provided. The authors suggest that improvements in disaster awareness and education of residents, flood-proofing of houses that are bound to be reconstructed after the earthquakes, and investment in a fully modern flood warning system would be beneficial. [ABSTRACT FROM AUTHOR]

Typhoon Haiyan (Yolanda) struck the islands of Leyte and Samar, the central part of the Philippines, on 8 November 2013, bringing large-scale devastation to coastal areas due to the high winds and large storm surge and waves associated with it. In order to obtain the distribution of storm surge heights and damage covering the wide stretch of affected coastline, the authors carried out a series of field surveys in the aftermath of the typhoon (in December 2013, May 2014, and October 2014). In the present paper, the authors detailed the results of these field surveys and summarized the characteristics of the storm surge and main causes of the damage, especially focusing on the Leyte Gulf coast, which is surrounded by the eastern coast of Leyte and the southern coast of Samar. Finally, the wide range of types of storm surge disasters were also discussed by comparing Typhoon Haiyan with other recent major events. [ABSTRACT FROM AUTHOR]

At 14:46 on March 11, 2011 (local time), a large earthquake of magnitude Mw 9.0 took place, generating a tsunami that caused severe damage to the east coast of Japan. To comprehensively record tsunami trace heights and impacts along the coastal region, the Tohoku Earthquake Tsunami Joint Survey Group was organized immediately after the event. As part of this group, the authors conducted a field survey in Miyagi and Fukushima Prefectures. The surveyed area can be divided into 2 parts from the point of view of its geographical features: the northern part (a rias coastal area) and the southern part (a coastal plain area). In this paper, the characteristics of the damage due to the tsunami in each area are analyzed by using both the results of the authors' own field survey and the Joint Survey Group. In the rias coastal area, inundation heights were more than 10 m, which resulted in the flooding of the low-lying grounds located at the inner part of the bays. The tsunami wave caused widespread destruction in this area, and coastal buildings (including reinforced concrete buildings) suffered severe damage. In the southern coastal plains, inundation heights were 5-10 m and the tsunami reached a few kilometers inland, though unfortunately there were not enough high locations or buildings for the residents to evacuate. In addition, an extensive line of coastal dikes and forests, which had been placed to protect the wide plains behind them, also suffered extensive damage. From these geographically dependent inundation and destruction patterns, a number of important lessons on how to modify and improve future risk management strategies can be obtained. [ABSTRACT FROM AUTHOR]

Land subsidence has triggered severe coastal floods in Jakarta, whose mechanism has been extensively investigated by researchers and engineers. The government has also recognized this fact, which has partially contributed to the recent announcement that the capital will be relocated to East Kalimantan. However, it is not clear whether ordinary people perceive the progress of land subsidence as their own issue. To ascertain this, a field survey was conducted after a major coastal flood that took place in December 2017, which revealed that nearly half of the people living in a rapidly sinking coastal community were not aware of the ongoing land subsidence under their own houses. Severe flood and land subsidence were not strongly recognized as interlinked problems by local citizens. Rain-induced flooding is common in the community, and this may explain why a quarter of respondents did not fear the 2017 coastal flood, despite their houses being flooded, in some cases to a depth above their heads. Land subsidence has an adverse effect on flooding. Awareness building programs for normal citizens should be promoted, in order to articulate the significance of stopping groundwater extraction for mitigating land subsidence and the flooding it induces. "Do you feel your house is sinking?" This figure shows the results of our survey in March 2018, consisting of interviews with 29 residents on flood triggered by the 2017 flood event and perception on land subsidence. The ground elevation was estimated based on our survey in November 2017. About half of the population do not recognize that land subsidence is ongoing under their own houses. Three respondents in this figure who experienced the highest floods (almost 2 m high) believed that their houses are NOT sinking. We initially hypothesized that the experience of suffering severe inundation would make people establish connection between flood and land subsidence. However, this connection appears not to be straightforward for local inhabitants. [Display omitted] • Land subsidence exacerbates flooding. Their connection is scientifically obvious. • However, it is not clear whether ordinary people perceive the progress of land subsidence as their own issue. • Nearly half of the respondents living in a rapidly sinking coastal community were not aware of the ongoing land subsidence. • Severe flood and land subsidence are not clearly recognized as interlinked problems by local citizens. • Awareness building programs should be promoted to articulate the significance of stopping groundwater extraction. [ABSTRACT FROM AUTHOR]

Typhoon Jebi struck Japan on the 4 September 2018, damaging and inundating many coastal areas along Osaka Bay due to the high winds, a storm surge, and wind driven waves. In order to understand the various damage mechanisms, the authors conducted a field survey two days after the typhoon made landfall, measuring inundation heights and depths at several locations in Hyogo Prefecture. The survey results showed that 0.18–1.27 m inundation depths were caused by Typhoon Jebi. As parts of the survey, local residents were interviewed about the flooding, and a questionnaire survey regarding awareness of typhoons and storm surges, and their response to the typhoon was distributed. The authors also mapped the location of some of the containers that were displaced by the storm surge, aiming to provide information to validate future simulation models of container displacement. Finally, some interesting characteristics of the storm surge are summarized, such as possible overtopping at what had initially been thought to be a low risk area (Suzukaze town), and lessons learnt in terms of disaster risk management are discussed. [ABSTRACT FROM AUTHOR]