Stress heterogeneity and its impact on seismicity pattern along the equatorial bifurcation zone of the Great Sumatran Fault, Indonesia

Sahara, David P.; Widiyantoro, Sri; Irsyam, Masyhur

doi:10.1016/j.jseaes.2018.06.002

Cited by 24 publications

(11 citation statements)

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“…To better assess seismic hazard potential of earthquakes in mainland Sumatra, published studies have focused on paleoearthquakes (Bellier et al, 1997), epicenter relocations (Hurukawa et al, 2014;Newcomb & McCann, 1987;Nugraha et al, 2018;Pesicek et al, 2010), aftershock distributions (Muzli et al, 2018;Widiwijayanti et al, 1996), field observations of surface ruptures (Daryono et al, 2012;Daryono & Tohari, 2016;Untung et al, 1985), deterministic and probabilistic hazard assessments (Natawidjaja & Triyoso, 2007), active fault mapping (Fernandez-Blanco et al, 2016;Muksin et al, 2019;Natawidjaja et al, 2017;Sieh & Natawidjaja, 2000;Weller et al, 2012), fault slip rates (Bellier & Sebrier, 1995;Bradley et al, 2017;Genrich et al, 2000;Ito et al, 2012;Natawidjaja et al, 2017;Prawirodirdjo et al, 2000;Tong et al, 2018), in situ stress analysis (Sahara et al, 2018), source characteristics of ruptures (Duquesnoy et al, 1996;Gunawan et al, 2018;Ito et al, 2016;Prawirodirdjo et al, 2000;Reid, 1913), and postseisimic processes (Gunawan et al, 2019). However, none of these studies used well-constrained near-field geodetic data to address the seismogenic depth and spatial distribution of coseismic slip, or to study the nature of the tectonic features that control earthquake rupture sizes along the SFZ.…”

Section: Introductionmentioning

confidence: 99%

Structural Controls on Rupture Extent of Recent Sumatran Fault Zone Earthquakes, Indonesia

et al. 2020

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Section: Introductionmentioning

confidence: 99%

Structural Controls on Rupture Extent of Recent Sumatran Fault Zone Earthquakes, Indonesia

et al. 2020

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“…The comparison result of the SHF of nearby coastal cities shows that the SHF of Bengkulu is higher than that of Padang. The results obtained in this study could be further integrated with stress heterogeneity analysis (Sahara et al 2018) to better understand the seismic hazard potential around the off-coast and near-coastal cities of the island of Sumatra.…”

Section: Discussionmentioning

confidence: 91%

Seismic Hazard Function (SHF) study of coastal sources of Sumatra Island: SHF evaluation of Padang and Bengkulu cities

et al. 2020

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Significant earthquakes on the island of Sumatra, Indonesia, have predominantly been earthquakes with a thrust mechanism that occurred due to the subduction process and seismotectonics near coastal cities of West and South Sumatra, which could be affected by earthquakes triggered by these seismic sources. We compared the Seismic Hazard Function (SHF) of two coastal cities of Sumatra: Bengkulu and Padang. The results showed that the SHF of Bengkulu is higher than that of Padang. Estimated earthquake hazards are presented in the form of seismic hazard maps expressed as the PGA of 10% rate of exceedance probability in 50 years. In estimating the seismic potential in Sumatra, the seismic moment rate was jointly estimated from the smoothed mean seismicity rate and the pre-seismic subduction surface strain rate model. In this study, the island of Sumatra was chosen as a master model for Seismic Hazard Analysis (SHA). The motivation for choosing Sumatra for the SHA was because of the large body of complete historical earthquake data of the North Western Sunda Arc. The SHF is calculated based on a magnitude range of 6.0 to 9.0 during 50 years with the radius distance from the source less than or equal to 100 km.

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“…Semua gempa dengan 𝑀 w ≥ 7,0 dipicu oleh aktivitas tektonik zona subduksi dan busur muka Sumatera dengan episenter di laut yang berarti bahwa wilayah pesisir barat Sumatera adalah sangat rentan mengalami bencana gempa dan tsunami (Wiseman et al, 2011;Triyoso et al, 2020). Gempa dengan kekuatan 𝑀 w < 7,0 sering terjadi dengan lokasi episenter di daratan Pulau Sumatera yang dipicu oleh aktivitas seismik Sesar Besar Sumatera (Cummins, 2017;Irsyam et al, 2017;Muzli et al, 2017;Natawidjaja et al, 2017;Gunawan et al, 2018;Sahara et al, 2018;Salman et al, 2020). Pesan penting Gambar 5 adalah semua gempa besar yang terjadi di Zona 1, Zona 2, dan Zona 3 berkorelasi dengan area nilai 𝑏 yang rendah (warna biru tua dominan pada Gambar 5).…”

Section: Variasi Spasial 𝒃-Valueunclassified

“…Sebagai akibat penunjaman miring tersebut di atas, struktur geologi dan tektonik Sumatera didominasi oleh zona subduksi aktif dekat Palung Sumatera di lepas pantai barat Sumatera, jalur busur muka Sumatera yang melintasi beberapa pulau kecil di lepas pantai barat Sumatera, dan jalur sesar aktif di daratan Pulau Sumatera yang dikenal sebagai Sesar Besar Sumatera (Sieh and Natawidjaja, 2000;Natawidjaja, 2002;McCaffrey, 2009;Weller et al, 2012;Haridhi et al, 2018;Hutchings and Mooney, 2021). Jalur Sesar Besar Sumatera ini memanjang dari wilayah utara (Ito et al, 2012;Muzli et al, 2018;Rafie et al, 2019) melewati wilayah tengah (Sahara et al, 2018) sampai wilayah selatan Pulau Sumatera (Natawidjaja et al, 2017). Gambaran tatanan tektonik Pulau Sumatera dapat dilihat pada Gambar 1.…”

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“…Aktivitas seismo-tektonik zona subduksi megathrust menyebabkan tekanan tektonik over geological time yang diakomodasi oleh Sesar Mentawai sebagai bagian dari zona seismik aktif busur muka Sumatera (Singh et al, 2010;Wiseman et al, 2011;Mukti et al, 2012) dan Sesar Besar Sumatera (Ito et al, 2012;Natawidjaja et al, 2017;Nugraha et al, 2018;Sahara et al, 2018) yang sejajar dengan Palung Sumatera dan pegunungan Bukit Barisan. Ketiga struktur geologi itu (zona subduksi, busur muka, dan Sesar Besar Sumatera) adalah sumber potensial pemicu bahaya bencana geologi (gempa tektonik dan tsunami) yang mengancam wilayah pesisir dan pedalaman sisi barat dari ujung utara sampai ujung selatan Pulau Sumatera (Natawidjaja et al, 2017;Gunawan et al, 2018;Rafie et al, 2019;Ratnasari et al, 2020;Salman et al, 2020;Triyoso et al, 2020).…”

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Analisis Seismisitas Dan Potensi Bahaya Bencana Seismik Pulau Sumatera Berdasarkan Data Gempa 1970-2020

MADLAZIM

Lestari

2022

IFI

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Abstrak Seismisitas Sumatera dan potensi bencana gempa tektonik dapat dipelajari melalui analisis parameter -value, -value, dan anomali -value. Nilai merefleksikan level seismisitas, nilai menunjukkan level stres batuan geologi bawah permukaan, dan anomali nilai bisa menjadi prekursor gempa besar. Ketiga parameter tersebut secara akurat diperoleh dengan memanfaatkan statistik frekuensi-magnitudo (FMD) gempa dari katalog USGS antara 1970-2020 dengan magnitudo antara 4,0 9,5 dan kedalaman mencapai 640 km. Kurva FMD menjadi basis penerapan hukum Gutenberg-Richter melalui pendekatan maximum likelihood. Perhitungan ketiga parameter dilakukan dengan membagi wilayah Sumatera menjadi Zona 1, Zona 2, dan Zona 3. Hasil-hasil perhitungan untuk Zona 1: = 6,02 dan = 0,76; Zona 2: = 6,50 dan = 0,84; dan Zona 3: = 6,86 dan = 0,88. Anomali nilai untuk ketiga zona seismik dinyatakan sebagai peta variasi spasio-temporal -value. Berdasarkan definisi -value dan -value, maka seismisitas Zona 3 (selatan Sumatera) paling tinggi dibandingkan dengan zona lain sedangkan struktur batuan bawah permukaan Zona 1 (utara Sumatera) memiliki stres paling tinggi yang relevan dengan peristiwa gempa besar yang sering terjadi. Analisis variasi spasio-temporal -value menemukan kesesuaian lokasi episenter gempa besar dengan daerah-daerah yang memiliki nilai yang rendah baik pada Zona 1, Zona 2 maupun Zona 3. Hal ini menunjukkan bahwa -drop dapat digunakan sebagai indikator gempa besar, sama seperti temuan terdahulu yang relevan dengan seismisitas Sumatera. Analisis histogram kedalaman sumber menunjukkan bahwa mayoritas gempa Sumatera adalah gempa dangkal dengan kedaaman rata-rata dalam rentang 30-40 km. Dengan demikian, seluruh wilayah Pulau Sumatera adalah rentan terhadap potensi bahaya bencana gempa tektonik. Kata Kunci: seismisitas Sumatera, -value, -value, anomali -value, hukum Gutenberg-Richter Abstract Seismicity in Sumatera and the potency for tectonic earthquakes can be examined using seismic parameters: -value, -value, and -value anomaly. Parameter -value reflects seismicity level, -value indicates the level of stress on subsurface structure, and -value anomaly is a precursor for a large event. The parameters were accurately calculated from USGS earthquake catalogue for frequency-magnitude distribution (FMD) in Sumatera between 1970-2020 with magnitudes 4.0 9.5 and the depths reaching 640 km beneath the surface. The FMD is a basis for the application of Gutenberg-Richter law through a maximum likelihood approach. Parameter calculation was performed by dividing Sumatera into Zone 1, Zone 2, and Zone 3. The results were for Zone 1: = 6.02 and = 0.76; Zone 2: = 6.50 and = 0.84; and Zone 3: = 6.86 and = 0.88. The anomaly was given as maps of spatio-temporal -value variations. Based on -value and -value definitions, seismicity in Zone 3 is the highest while subsurface structure in Zone 1 shows the highest stress, relevant to frequent large occurrences in this zone. Analysis of spatial and temporal -value anomalies found correlation between locations of large earthquake epicentres and regions of low-lying -value in all seismic zones. This suggests that b-drop is a good indicator for a large event, in good agreement with previous findings relevant to Sumatera seismicity. Analysis of earthquake source reveals that shallow sources are dominant with the average depth lies between 30-40 km. Thus, the whole island is vulnerable to seismic hazards. Keywords: Sumatera seismicity, -value, -value, -value anomaly, Gutenberg-Richter law

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Stress heterogeneity and its impact on seismicity pattern along the equatorial bifurcation zone of the Great Sumatran Fault, Indonesia

Cited by 24 publications

References 39 publications

Structural Controls on Rupture Extent of Recent Sumatran Fault Zone Earthquakes, Indonesia

Structural Controls on Rupture Extent of Recent Sumatran Fault Zone Earthquakes, Indonesia

Seismic Hazard Function (SHF) study of coastal sources of Sumatra Island: SHF evaluation of Padang and Bengkulu cities

Analisis Seismisitas Dan Potensi Bahaya Bencana Seismik Pulau Sumatera Berdasarkan Data Gempa 1970-2020

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