Lithological Identification of Devastated Area by Pidie Jaya Earthquake Through Poisson’s Ratio Analysis

Abstract

A combination of geophysical methods has been applied in the earthquake-devastated area in late December of 2016 in Pidie Jaya Regency, Aceh Province, Indonesia. The methods are refraction seismic and Multichannel Analysis Surface Wave (MASW). This research aims to identify the types of near-surface lithologies through Poisson's ratio analysis. These velocity values were acquired through measurements in three sites among the devastated areas. The measurement of VP and VS values deploys the PASI 16S Seismograph with 24 channels. The geometry of seismic refraction lines was designed by placing 2-meter long geophone intervals, and nine total shot points were inserted, while in VS data measurement, the geophone intervals were the same set as the refraction seismic with differently laid out geometry of shot points and total. Both data were processed using ZondST2D for the 2D profile of VP and SeisImager for 2D section of VS. The result of the study indicated that all of the Poisson's ratio profiles show lithology consisting of clayey sand, clay and saturated clay with a value generally ranging from 0.22 to 0.46. The clay lithology is a prominent finding of this research. These interpretations more or less match other results even though some are in different research areas. This finding was proven by the damaged area affected by the earthquake in late 2016. Thus the result can be beneficial to designing and customizing building types according to lithological characteristics then mitigating from the forthcoming threat of the earthquake.

Continuity of Great Sumatran Fault in the Marine Area Revealed by 3d Inversion of Gravity Data

“…Still, only at a depth of 0 -200 km, which has a relatively more earthquake distribution, the 200 km of the depth is used in model assumption and the Bouguer anomaly in mGal as the input parameter for inversion of 3D gravity. Furthermore, the geological constraints (density values) are used in the range of 2 -3 g/cm 3 . This density is obtained from the 2D modeling of gravitational data in the Andaman Islands that are relatively close to the study area [25], where the water layer is 1.03 g/cm 3 , crust 2.7 g/cm 3 , and mantle 3.3 g/cm 3 .…”

“…Furthermore, the geological constraints (density values) are used in the range of 2 -3 g/cm 3 . This density is obtained from the 2D modeling of gravitational data in the Andaman Islands that are relatively close to the study area [25], where the water layer is 1.03 g/cm 3 , crust 2.7 g/cm 3 , and mantle 3.3 g/cm 3 . The contrast of background density, i.e., 2.1 and 2.67, was selected for modeling the GSF structure.…”

“…Such a long fault system splits into 20 segments. The seismic activity along the GSF has been studied extensively, primarily on the ground using geological and geodetic studies [1] and active fault mapping along the Sumatran fault trajectory based on seismological and geomorphological data [2], [3].…”

Efficient Use of Satellite Gravity Anomalies for mapping the Great Sumatran Fault in Aceh Province

“…Geophysical methods have been widely used for fault mapping, for example, in Lamtamot village along the Seulimeuem segment [4] , lithological identification on the devastated area of the Pidie Jaya earthquake [5] . Furthermore, the geophysical surveys are considerably fast and cost-effectiveness compared to other methods, they are still expensive and time consuming for the regional-scale survey [6] .…”

Estimation of Vs Structure of Krueng Aceh and its Suburb Basin of Aceh Province, Indonesia, Derived from Microtremor Measurements

“…The identical research has also been performed [9] by identifying near-surface soil using Poisson's ratio analysis in an area hit by a destructive earthquake (i.e., Pidie Jaya Regency, Aceh Province, Indonesia). The study involved Vs measurements using the multi-channel analysis of surface wave (MASW) survey.…”