Developing Tsunami fragility curves using remote sensing and survey data of the 2010 Chilean Tsunami in Dichato

E Mas,T Yoshii,F Yamazaki,C Jimenez,S Koshimura,M Matsuoka,M Matsuyama,A Suppasri,F Imamura

doi:10.5194/nhess-12-2689-2012

Abstract

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.

Highlights

The largest earthquake in history was the 1960 Chile earthquake and tsunami
Tsunami fragility is implemented for an assessment of structural damage within the exposed area from potential tsunami hazard scenarios
Using inundation depth from the posttsunami field survey data of the 27 February 2010 Chile earthquake, and through the inspection of damage using satellite imagery of the pre- and post-event in Dichato, tsunami fragility curves were constructed for the first time in a southwestern Pacific country

Summary

Introduction

The largest earthquake in history was the 1960 Chile earthquake and tsunami. Following the north edge of this rupture area, on 27 February 2010 a megathrust earthquake of Mw = 8.8 occurred. The earthquake generated a destructive tsunami in Chile and the whole Pacific. It is the third largest earthquake in the 21st century and eighth in the recorded history; it is known as the Maule Earthquake. The ruptured area was of nearly 450 km, extending from southern Santiago in the north to the Arauco Peninsula in the southern area of the city of Concepcion. This earthquake was an inter-plate mega-subduction event with a pure reverse mechanism (Pulido et al, 2010).

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