The Seismicity of Indonesia and Tectonic Implications

Hutchings, Sean J.; Mooney, Walter D.

doi:10.1029/2021gc009812

Cited by 50 publications

(73 citation statements)

References 117 publications

(712 reference statements)

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“…Between these two regions lies the Java Island, whose tectonic regime at the transition between the two domains is less clear. The island is the locus of intense volcanic and seismotectonic activity ( Hutchings & Mooney, 2021 ). Yet, its tectonic structure received less attention than the other islands of the arc, despite the fact that the western part of Java is the most densely populated part of Indonesia.…”

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confidence: 99%

Active Back‐Arc Thrust in North West Java, Indonesia

Aribowo

Husson

Natawidjaja³

et al. 2022

Tectonics

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The Java Back‐arc Thrust scars the entire back‐arc area of Java Island, but the faults' nature, timing, and activity remain partly elusive. Characterizing the structure and activity of the seismogenic Java Back‐arc Thrust (historical earthquakes up to 7 Mw) is a cornerstone to evaluate associated geohazards. We focus on the western part of Java Back‐arc Thrust that reaches the megalopolis of Jakarta. We combine morphotectonic data, seismic reflection, electric resistivity profiles, kinematic, structural field measurements, paleoseismological trenching, and sediment dating (optically stimulated luminescence and 14C). Our results suggest that the interplay between the faults, volcanoes, and sedimentary basin modulates the propagation of the fault system across and along‐strike. The West Java Back‐arc Thrust has been active from Pliocene to Recent, but with a laterally variable tempo and tectonic regime. While tectonic activity was sustained for longer times in the eastern part, the West Java Back‐arc Thrust broke through the Jakarta Basin in the west, possibly only since the Late Pleistocene, and partitions into a network of immature transpressive structures. We conclude that the West Java Back‐arc Thrust has a high seismic hazard that requires a careful risk evaluation along its trace, as it threatens the numerous infrastructures of the densely populated West Java.

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confidence: 99%

Active Back‐Arc Thrust in North West Java, Indonesia

Aribowo

Husson

Natawidjaja³

et al. 2022

Tectonics

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“…According to Cardwell et al (1980), the subducting slab to the east under the Halmahera Arc subducts at an angle of ~45 o and reaches a depth of ~230 km; Hall and Spakman (2015) show that it reaches depths of ~400 km, which is in line with recent research (Chen et al 2020) that used 3-D earthquake data distribution plots from ISC-EHB to identify slab configurations that were not modeled by slab2. Hutchings and Mooney (2021) show that the subducted slab in the Sangihe Arc at depths of ~250 to 350 km has a seismic gap, while the tomography image of the slab appears to be continuous.…”

Section: Introductionmentioning

confidence: 90%

“…This feature can be interpreted as rock material that experienced micro-cracks that have since closed due to high pressure (Bariş et al 2005;Zheng and Lay 2006;Wagner et al 2008;Zenonos et al 2020). The D4 area, located beneath the island of Tifore in the Central Molucca Sea, is an upraised ophiolite body (Widiwijayanti et al 2003(Widiwijayanti et al , 2004 which has an active thrust fault (McCaffrey 1982;Hutchings and Mooney 2021). The tectonic activity in this area causes many earthquakes of both small and large magnitudes.…”

Section: Double Subduction Of the Molucca Sea Platementioning

confidence: 99%

“…The collision is ~250 km apart (Morris et al 1983) and convergently collides with the Molucca Sea Plate (Morris et al 1983;Hafkenscheid et al 2001) at a movement of 1.5 cm/yr (Hafkenscheid et al 2001). The Molucca Sea Plate has an inverted U-or V-shape (Hatherton and Dickinson 1969;Cardwell et al 1980;McCaffrey et al 1980;McCaffrey 1982;Hall 1987;Hutchings and Mooney 2021) and has slab subducts to the west under the Sangihe Arc and subducts to the east under the Halmahera Arc. The subduction of the Molucca Sea Plate in both eastern and western directions makes for arc volcanisms in the Halmahera and Sangihe Arcs that run parallel to the subduction zone (Robert Hall, 1987;Milsom et al, 1992;Hatherton & Dickinson, 1969) with its Wadati-Benioff Zone at a depth of 100 km (Hamilton A1979;Cardwell et al 1980;Morris et al 1983).…”

Section: Introductionmentioning

confidence: 99%

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Travel Time Tomography Beneath the Molucca Sea Collision Zone Based on Local and Regional BMKG Networks Using a 3-D Model

Rachman

Santosa

Nugraha

et al. 2022

Preprint

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This study’s research aim has been to clearly reveal the geometry of the Molucca Sea Plate subduction zone beneath Sulawesi’s north arm, the relationship between the subduction zone and volcanic activity in Halmahera, and analyze the depths of the upper arch of the double subduction of the Molucca Sea Plate. The use of travel time tomography made it possible to reconstruct subsurface images of the complex Molucca Sea Collision Zone at greater depths and in more detail. Local and regional arrival times of P- and S- wave data from the BMKG station network were used. The network consists of 32 stations; data was recorded from January 1, 2010 to December 31, 2017. Events with magnitude > 4 were used, comprising a total of 1,647 events. The same amount of P- and S-wave arrival times were repicked at each station; ~17,628 P-wave phases and ~17,628 S-wave phases were identified. Probabilistic non-linear location was used to determine the earthquake hypocenter along with the damped least square method with 3-D seismic velocity as the initial model beneath Indonesia for the travel time tomography inversion. The tomographic inversion results show that high Vp, high Vs, and low Vp/Vs beneath the Gorontalo Basin and Sulawesi’s north arm are associated with the Molucca Sea Plate, geometrically subducting to the north at a ~40° angle. Also observed were low-Vp, low-Vs, and high-Vp/Vs in the crust mantle beneath the northern and southern Halmahera Volcanic Arc (Bacan Island), which might be associated with a possible magma source. Volcanoes in the northern part have experienced eruptions, e.g., the Gamkonora and Ibu Volcanoes. Meanwhile, volcanos in the southern part are in a dormant state and their last eruptions are unknown. This latter group of volcanoes is clearly connected with partial melting (low-Vp, low-Vs, high-Vp/Vs) above the Molucca Sea Plate, which subducts to the east. The double subduction of the Molucca Sea Plate is shown by high-Vp, high-Vs, low-Vp/Vs which subduct westward beneath Sulawesi’s north arm and the Sangihe Islands, and subducts eastward beneath Halmahera Island. The tomographic image also shows that the Molucca Sea Plate in the north is sinking deeper (at a depth of ~150 km) compared to the south (at a depth of ~50 km). Anomalies of low-Vp, low-Vs, and high-Vp/Vs in the crust mantle beneath the Central Ridge of the Molucca Sea indicate highly fractured and water-saturated rock material; while in the west and east, beneath the Sangihe Trench (ST) and Halmahera Trench (HT), the anomaly of high-Vp, high-Vs and low-Vp/Vs indicate rock material that experienced micro-cracks that have since been closed due to high pressure. Further north, the highly fractured and water-saturated rock material shifted eastward, extending to the HT with a clear boundary in the Central Molucca Sea.

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“…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).…”

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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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The Seismicity of Indonesia and Tectonic Implications

Cited by 50 publications

References 117 publications

Active Back‐Arc Thrust in North West Java, Indonesia

Active Back‐Arc Thrust in North West Java, Indonesia

Travel Time Tomography Beneath the Molucca Sea Collision Zone Based on Local and Regional BMKG Networks Using a 3-D Model

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

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