TSUNAMI HAZARD AND BUILDING DAMAGE ASSESSMENT IN THAILAND USING NUMERICAL MODEL AND FRAGILITY CURVES

2013 ◽  
Vol 07 (05) ◽  
pp. 1250028 ◽  
Author(s):  
ANAWAT SUPPASRI ◽  
FUMIHIKO IMAMURA ◽  
SHUNICHI KOSHIMURA

Assessing the hazard and damage of a potential tsunami is an ongoing challenge in tsunami research. This study begins by simulating tsunami hazards using historical events. A tsunami propagation model is used to obtain the estimated maximum tsunami height along the west coast of Thailand for a rough return period, and rupture locations that have the potential to generate catastrophic tsunamis in Thailand for a specific return period are proposed. A tsunami inundation model is then performed to quantify each building's maximum inundation depth, using high-resolution satellite images to extract each building's location for the areas of interest located in southern Thailand. Nam Khem village and Patong beach are selected as study areas to represent village communities and tourist attractions, respectively. The model results are then used to obtain the numbers of exposed inhabitants and buildings for each earthquake return period. The developed tsunami fragility curves are applied to these figures to determine the number of potentially damaged buildings. The analysis suggests that the propagation model can be used to obtain rough estimations because it provided results similar to those of the inundation model. However, material type must be considered when fragility curves are used in a different country (i.e. reinforced concrete buildings in Thailand from the 2004 tsunami and wooden houses in Japan from the 2011 East Japan tsunami).

2011 ◽  
Vol 11 (1) ◽  
pp. 173-189 ◽  
Author(s):  
A. Suppasri ◽  
S. Koshimura ◽  
F. Imamura

Abstract. The 2004 Indian Ocean tsunami damaged and destroyed numerous buildings and houses in Thailand. Estimation of tsunami impact to buildings from this event and evaluation of the potential risks are important but still in progress. The tsunami fragility curve is a function used to estimate the structural fragility against tsunami hazards. This study was undertaken to develop fragility curves using visual inspection of high-resolution satellite images (IKONOS) taken before and after tsunami events to classify whether the buildings were destroyed or not based on the remaining roof. Then, a tsunami inundation model is created to reconstruct the tsunami features such as inundation depth, current velocity, and hydrodynamic force of the event. It is assumed that the fragility curves are expressed as normal or lognormal distribution functions and the estimation of the median and log-standard deviation is performed using least square fitting. From the results, the developed fragility curves for different types of building materials (mixed type, reinforced concrete and wood) show consistent performance in damage probability and when compared to the existing curves for other locations.


2012 ◽  
Vol 12 (8) ◽  
pp. 2689-2697 ◽  
Author(s):  
E. Mas ◽  
S. Koshimura ◽  
A. Suppasri ◽  
M. Matsuoka ◽  
M. Matsuyama ◽  
...  

Abstract. On 27 February 2010, a megathrust earthquake of Mw = 8.8 generated a destructive tsunami in Chile. It struck not only Chilean coast but propagated all the way to Japan. After the event occurred, the post-tsunami survey team was assembled, funded by the Japan Science and Technology Agency (JST), to survey the area severely affected by the tsunami. The tsunami damaged and destroyed numerous houses, especially in the town of Dichato. In order to estimate the structural fragility against tsunami hazard in this area, tsunami fragility curves were developed. Surveyed data of inundation depth and visual inspection of satellite images of Dichato were used to classify the damage to housing. A practical method suitable when there are limitations on available data for numerical simulation or damage evaluation from surveys is presented here. This study is the first application of tsunami fragility curves on the South American Pacific coast and it might be of practical use for communities with similar characteristics along the west Pacific coast. The proposed curve suggests that structures in Dichato will be severely damaged – with a 68% probability – already at 2 m tsunami inundation depth.


2014 ◽  
Vol 2 (1) ◽  
pp. 1-25
Author(s):  
H. Gokon ◽  
S. Koshimura ◽  
K. Imai ◽  
M. Matsuoka ◽  
Y. Namegaya ◽  
...  

Abstract. Fragility functions in terms of flow depth, flow velocity and hydrodynamic force are developed to evaluate structural vulnerability in the areas affected by the 2009 Samoa earthquake and tsunami. First, numerical simulations of tsunami propagation and inundation are conducted to reproduce the features of tsunami inundation. To validate the results, flow depths measured in field surveys and waveforms measured by Deep-ocean Assessment and Reporting of Tsunamis (DART) gauges are utilized. Next, building damage is investigated by manually detecting changes between pre- and post-tsunami high-resolution satellite images. Finally, the data related to tsunami features and building damage are integrated using GIS, and tsunami fragility functions are developed based on the statistical analyses.


2014 ◽  
Vol 14 (12) ◽  
pp. 3231-3241 ◽  
Author(s):  
H. Gokon ◽  
S. Koshimura ◽  
K. Imai ◽  
M. Matsuoka ◽  
Y. Namegaya ◽  
...  

Abstract. Fragility functions in terms of flow depth, flow velocity and hydrodynamic force are developed to evaluate structural vulnerability in the areas affected by the 2009 Samoa earthquake and tsunami. First, numerical simulations of tsunami propagation and inundation are conducted to reproduce the features of tsunami inundation. To validate the results, flow depths measured in field surveys and waveforms measured by Deep-ocean Assessment and Reporting of Tsunamis (DART) gauges are utilized. Next, building damage is investigated by visually interpreting changes between pre- and post-tsunami high-resolution satellite images. Finally, the data related to tsunami features and building damage are integrated using Geographic Information System (GIS), and tsunami fragility functions are developed based on the statistical analyses. From the developed fragility functions, we quantitatively understood the vulnerability of a coastal region in American Samoa characterized by steep terrains and ria coasts.


Author(s):  
Hideki Kaida ◽  
Naoto Kihara

In the safe design and risk assessment of structures in coastal area, it is important to consider tsunami-borne debris impact. Recently, probabilistic analysis has become the preferred form of analysis because of the large aleatory and epistemic uncertainties associated with tsunami effects, which are not captured in deterministic scenario-based assessments. By performing both a probabilistic tsunami hazard assessment (PTHA) and a tsunami fragility assessment (TFA) on structures, their annual failure frequency can be determined. The TFA involves evaluation of the response (e.g. debris impact force exerted on the structure) and the capacity of the structure to resist tsunami effects. Then, a fragility curve shows conditional damage probability of the structure for the tsunami magnitude (e.g., discrete tsunami height around the focused area). This study proposes a TFA methodology for tsunami-borne debris impact, as this has not yet been sufficiently established. Evaluation of the impact speed and impact probability of debris considering various uncertainties in the response evaluation are described in particular detail. Moreover, an assessment of a coastal industrial site was performed and fragility curves and the annual failure frequency of structures against debris impact were shown.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/es-ny8eIUfc


Author(s):  
Jui-Chun Freya Chen ◽  
Wu-Cheng Chi ◽  
Chu-Fang Yang

Abstract Developing new ways to observe tsunami contributes to tsunami research. Tidal and deep-ocean gauges are typically used for coastal and offshore observations. Recently, tsunami-induced ground tilts offer a new possibility. The ground tilt signal accompanied by 2010 Mw 8.8 Chilean earthquake were observed at a tiltmeter network in Japan. However, tiltmeter stations are usually not as widely installed as broadband seismometers in other countries. Here, we studied broadband seismic records from Japan’s F-net and found ground tilt signals consistent with previously published tiltmeter dataset for this particular tsunamic event. Similar waveforms can also be found in broadband seismic networks in other countries, such as Taiwan, as well as an ocean-bottom seismometer. We documented a consistent time sequence of evolving back-azimuth directions of the tsunami waves at different stages of tsunami propagation through beamforming-frequency–wavenumber analysis and particle-motion analysis; the outcomes are consistent with the tsunami propagation model provided by the Pacific Tsunami Warning Center. These results shown that dense broadband seismic networks can provide a useful complementary dataset, in addition to tiltmeter arrays and other networks, to study or even monitor tsunami propagation using arrayed methods.


2016 ◽  
Vol 11 (6) ◽  
pp. 1161-1175 ◽  
Author(s):  
Daisuke Kuribayashi ◽  
◽  
Miho Ohara ◽  
Takahiro Sayama ◽  
Atsuhiko Konja ◽  
...  

This paper proposes a method to evaluate the flood risk of each district in a municipality to assist disaster management personnel. The method is specifically for municipalities in a mountainous region where insufficient information is available for practical disaster management. Using this method, we conducted inundation analysis for multiple patterns of rainfall and discharge using a rainfall-runoff-inundation model, and estimated the maximum inundation depth and duration. Based on the estimation, we developed a “flood diagnostic chart” to evaluate district-level flood risk, additionally considering other indicators. Moreover, we located flood hotspots, which are areas requiring extra precautions because of the high flood risk for districts.


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