Exposure and loss assessment of soil liquefaction in coastal area of Kulon Progo, Indonesia

Ghiffari Rizki,Rijanta Raden,Rachmawati Rini

doi:10.1051/e3sconf/202020002008

Abstract

Soil Liquefaction is a phenomenon of loss of strength of the granural soil layers due to increased pore water stress caused by earthquake shocks. Soil liquefaction can cause material and life damage if occurs in the developed area. Kulon Progo Regency based on the Atlas of Liquefaction Susceptibility Zones in 2019, has high susceptibility zones, which has the potential for flow liquefaction, lateral spreading, vertical displacement, and sand boil. This study aims to assess the exposure and loss index in liquefaction hazard zone based on the characteristics of land use and social demographic. The exposure index is obtained from overlaying between susceptibility map and liquefaction exposure variables, when the loss assessment is done by simulating the losses in several earthquake moment magnitude scenarios. Study results show that high exposure surrounding the residential zone in the south of the Wates Urban Area and the construction location of the Yogyakarta International Airport. There are settlement areas potentially affected by lateral spreading in Glagah, Karangwuni, Banaran, and Karangsewu Villages. While the results of the loss assessment show that transport infrastructure and residential buildings are the most affected objects when liquefaction phenomena occur due to the earthquake. Managing the expansion of settlement area through zoning regulation and technical engineering approach is needed to reduce losses due to future liquefaction phenomenon.

Highlights

The Kulon Progo coastal area has been the focus of various researches for years on the topic of disaster, especially earthquake and tsunami disasters
This study aims to assess the level of exposure and losses in each liquefaction susceptibility zone around the Yogyakarta International Airport development site which is part of the coastal areas of Temon Subdistrict, Wates Subdistrict, Panjatan Subdistrict, and Galur Subdistrict, in Kulon Progo Regency
Existing land use data were obtained from Rupa Bumi Indonesia maps of Kulon Progo Regency which was updated based on field observations

Summary

Introduction

The Kulon Progo coastal area has been the focus of various researches for years on the topic of disaster, especially earthquake and tsunami disasters. There are other disaster threats that need special attention in the development of the coastal region of Kulon Progo Regency, namely soil liquefaction due to the earthquake. Liquefaction is the phenomenon of loss of soil strength due to an increase in pore tension caused by dynamic loads from an earthquake. Liquefaction can occur if the maximum surface acceleration reaches >0.1 g with earthquake strength >5 on the Ritcher Scale or >VII on the Mercali Scale [1]. Liquefaction generally occurs in granular or coarsegrained soils and has very little cohesion value. Characteristics include gravel and dominant sand with little or no clay content [2]

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