Analysis of b-Value and Peak Ground Acceleration (PGA) in West Sumatra Province using Maximum Likelihood Method and Empirical Formula (Earthquake data Period 2007-2020)

Fandu Alfadilah - Department of Physics, Universitas Negeri Padang, West Sumatra
- Syafriani - Department of Physics, Universitas Negeri Padang, West Sumatra
- Hamdi - Department of Physics, Universitas Negeri Padang, West Sumatra
Letmi Dwiridal - Department of Physics, Universitas Negeri Padang, West Sumatra
Fajri Rahmatullah - Badan Meteorologi Klimatologi dan Geofisika, Jalan Angkasa 1 No. 2 Kemayoran Jakarta Pusat

Abstract


West Sumatra Province has four active fault segments, namely part of the Sumatran fault zone which causes frequent earthquakes. Therefore, it is necessary to research b-value analysis and PGA in the province of West Sumatra by using the maximum likelihood method and empirical formula for earthquake disaster mitigation efforts. This study aims to determine the b-value associated with rock stress and PGA as the level of earthquake activity and analyze the distribution map. The data used is earthquake data for the period 2007-2020 with a magnitude ≥ 5 SR and a depth of ≤ 100 km. The results of data processing produce a map of the distribution of b-value and PGA in the province of West Sumatra. The b-value in each region ranged from 0.8421-1.4477. Based on the b-value distribution map, the area that has the smallest b-value is in region 6, while the largest value is in region 2. A low b-value correlates with high rock stress conditions. This value illustrates that area 6 has a high chance of a major earthquake occurring. Furthermore, the calculation of the PGA value refers to the general form of Lin and Wu's empirical equation to obtain a new empirical formula model. The value of the coefficient a=−1.20543, b=−0.839093, and c=6.88858. The PGA value of West Sumatra province ranges from 10.87-376.98 gal. The city/regency with the largest PGA value is in the Mentawai Islands Regency, which ranges from 84.11-328.17 gal and the lowest value is in Dharmasraya Regency, which is between 10.87-35.28 gal.

Full Text:

PDF

References


K. Sakdiyah and A. Choiruddin, “Model Inhomogeneous Log-Gaussian Cox Process ( LGCP ) untuk Pemetaan Risiko Gempa Bumi di Sumatra,” J. Sains dan Seni ITS, vol. 9, no. 2, pp. 108–114, 2020.

K. R. Newcomb and W. R. McCann, “Seismic History and Seismotectonics of the Sunda Arc,” J. Geophys. Res., vol. 92, no. B1, pp. 421–439, 1987.

Madlazim, “Kajian Awal tentang b Value Gempa Bumi di Sumatra Tahun 1964-2013,” J. Penelit. Fis. dan Apl., vol. 3, no. 1, pp. 41–46, 2013.

M. Diament and dkk, “Mentawai Fault Zone Off Sumatra: A New Key to the Geodynamics of Western Indonesia,” Geology., vol. 20, no. 3, pp. 259–262, 1992.

R. Triyono, “Ancaman Gempabumi di Sumatera Tidak hanya Bersumber dari Mentawai Megathrust,” Stasiun Geofisika Kelas I Padang Panjang, p. 3, 2015.

E. R. Hartuti, “Buku Pintar Gempa: Mengenal Seluk Beluk Gempa, Jenis-Jenisnya, Penyebab-penyebabnya, dan Dampak-dampaknya,” Yogyakarta: DIVA Press, 2009.

F. D. Raharjo, Syafriani, and A. Z. Sabarani, “Analisis Variasi Spasial Parameter Seismotektonik Daerah Sumatera Barat dan Sekitarnya dengan Menggunakan Metode Likelihood,” Pillar Phys., vol. 8, pp. 73–80, 2016.

W. Asnita, D. Sugiyanto, and I. Rusydy, “Kajian Statistik Seismisitas Kawasan Sumatera,” J. Nat., vol. 16, no. 2, pp. 5–9, 2016.

C. H. Scholz, “The Frequency Magnitude Relation of Micro Fracturing in Rock and its Relation to Earthquakes,” Bull. Seismol. Soc. Am., vol. 58, no. 1, pp. 399–415, 1968.

S. J. Gibowicz, “Variation of the Frequency-Magnitude Relation During Earthquake Sequences in New Zealand,” Bull. Seismol. Soc. Am., vol. 63, no. 2, pp. 517–528, 1973.

B. Sunardi, “Analisa Fraktal dan Rasio Slip Daerah Bali-NTB Berdasarkan Pemetaan Variasi Parameter Tektonik,” J. Meteorol. dan Geofis., vol. 10, no. 1, pp. 58–65, 2009.

Mandasari, Syafriani, R. Triyono, and R. Hendra, “Analisis Tingkat Kerentanan Seismik di Sumatera Barat Berdasarkan Nilai Percepatan Tanah Maksimum dan Intensitas Maksimum (Periode Data Gempa Tahun 2007-2017),” Pillar Phys., vol. 11, no. 2, pp. 17–24, 2018.

M. Leviana, Syafriani, and A. Z. Sabarani, “Estimasi Nilai Percepatan Tanah Maksimum Wilayah Sumatera Barat Berdasarkan Skenario Gempabumi M 8.8 SR Menggunakan Rumusan Empiris Mc. Guire (1963) dan Donovan (1973),” Pillar Phys. vol. 10, pp. 55–62, 2017.

Z. Netrisa, Syafriani, R. Triyono, and H. Arifin, “Pemetaan Bahaya Gempabumi Deterministik dengan Pendekatan Peak Ground Acceleration ( PGA ) di Kota Padang,” Pillar Phys., vol. 11, no. 2, pp. 41–48, 2018.

L. Linkimer, “Relationship Between Peak Ground Acceleration and Modified Mercalli Intensity in Costa Rica,” Revista Geologica de America Central, no. 38, pp 81–94, 2008.

J. Douglas, “Ground motion prediction equations 1964-2018,” United Kingdom: Department of Civil and Environmental Engineering: University of Strathclyde, 2018.

L. Esteva, and R. Villaverde, “Seismic Risk, Design Spectra and Structural Reliability,” in Proceedings of Fifth World Conference on Earthquake Engineering, vol. 2, pp. 2586–2596, 1976.

T. L. Lin, and Y. M. Wu, “Magnitude Determination using Strong Ground-Motion Attenuation in Earthquake Early Warning,” Geophys. Res. Lett., vol. 37, no. 7, pp. 1–5, 2010.




DOI: http://dx.doi.org/10.24036/12553171074