Studi Mikrozonasi Berdasarkan Integrasi Data Mikrotremor Array dan Mikrotremor Single Station di Daerah Gresik

Paramita, Eksi Galih Kenya (2024) Studi Mikrozonasi Berdasarkan Integrasi Data Mikrotremor Array dan Mikrotremor Single Station di Daerah Gresik. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Gresik merupakan salah satu wilayah yang berada dekat dengan sesar aktif, tepatnya sesar Kendeng yang melalui Surabaya dengan karakter sesar naik dan beberapa sesar aktif di Laut Jawa. Kondisi tersebut menjadikan daerah ini cukup dekat dengan sumber gempa. Sebagai kawasan yang juga kedepannya akan terus dikembangkan, maka perlu adanya identifikasi secara komprehensif terkait potensi kebencanaan geologi di Gresik. Dalam kajian ini digunakan integrasi data mikrotremor single station dan array menggunakan pendekatan HVSR (Horizontal to Vertical Spectral Ratio) dan SPAC (Spatial Autocorrelation) untuk menentukan sebaran tingkat kerentanan wilayah terhadap guncangan tanah yang berasosiasi dengan karakteristik litologi berdasarkan nilai faktor penguatan gelombang atau disebut mikrozonasi. Hasil penelitian ini menunjukkan kondisi yang cukup berbeda, dimana distribusi nilai faktor penguatan gelombang yang tinggi tidak hanya berada pada aluvium, melainkan juga pada formasi lainnya, dengan nilai faktor 1,2 – 2,1. Hal ini diperkuat juga oleh kontras impedansi (kontras kecepatan gelombang geser) antara sedimen permukaan dan batuan yang mengalasinya, dimana Vs sedimen permukaan daerah tersebut berkisar antara 150 m/s – 206 m/s, dan nilai Vs batuan yang mengalasi soft sediment berkisar antara 360 m/s – 506 m/s. Hal tersebut diduga karena pengaruh proses sedimentasi pada area tersebut berasal dari lapukan batuan alasnya sendiri (batugamping, batupasir) menjadi lapisan di atasnya atau sedimen permukaan, sehingga kontras impedansi antara lapisan sedimen permukaan dengan batuan yang mengalasinya cukup tinggi.
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Gresik is one of the areas close to an active fault, precisely the Kendeng fault through Surabaya with a reverse fault character and several active faults in the Java Sea. These conditions make this area quite close to the earthquake source. As an area that will also continue to be developed in the future, it is necessary to comprehensively identify the potential for geological disasters in Gresik. In this study, the integration of single station and array microtremor data using the HVSR (Horizontal to Vertical Spectral Ratio) and SPAC (Spatial Autocorrelation) approach is used to determine the distribution of regional vulnerability levels to ground shaking associated with lithological characteristics based on the value of the wave amplification factor or called microzonation. The results of this study show quite different conditions, where the distribution of high wave amplification factor values is not only in the alluvium, but also in other formations, with factor values of 1.2 – 2.1. This is reinforced by the impedance contrast (shear wave velocity contrast) between the surficial sediments and the underlying rock, where the Vs of the surficial sediments range from 150 m/s – 206 m/s, and the Vs rock overlying soft sediment range from 360 m/s – 506 m/s. This is thought to be due to the influence of the sedimentation process in the area comes from the weathering of the bedrock itself (limestone, sandstone) into the overlying layers or surface sediments, so that the impedance contrast between the surface sediment layer and the underlying rock is quite high

Item Type:	Thesis (Other)
Uncontrolled Keywords:	HVSR, Mikrotremor, Mikrozonasi, Site Amplification, SPAC, Microtremor, Microzonation
Subjects:	H Social Sciences > HV Social pathology. Social and public welfare > HV551.5.I4 Hazard mitigation Q Science > QE Geology > QE538.5 Seismic tomography; Seismic waves. Elastic waves Q Science > QE Geology > QE538.8 Earthquakes. Seismology T Technology > T Technology (General) > T174.5 Technology--Risk assessment.
Divisions:	Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Geophysics Engineering > 33201-(S1) Undergraduate Thesis
Depositing User:	Eksi Galih Kenya Paramita
Date Deposited:	06 Aug 2024 02:14
Last Modified:	02 Sep 2024 02:51
URI:	http://repository.its.ac.id/id/eprint/111395

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