Preliminary Magnitude of Completeness Quantification of Improved BMKG Catalog (2008-2016) in Indonesian Region

Diantari, H C; Suryanto, Wiwit; Anggraini, Ade Eka; Irnaka, Theodosius Marwan; Susilanto, Pupung; Ngadmanto, Drajat

doi:10.1088/1755-1315/132/1/012026

Cited by 9 publications

(21 citation statements)

References 5 publications

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“…Keep it in mind, it is obvious from Table 3 that the BC provides high consistency of the mean 𝑏-value obtained either for the provinces or the coverage sides of the provinces (with respect to any choice of the three algorithms). Taking this as a basis for concluding remarks, the mean 𝑏-value found for NTB is less than that held for NTT, suggesting that NTT has a higher level of seismicity rates than NTB, in good agreement with previous studies of the recent Indonesian seismicity, claiming higher seismicity in the eastern part [13] or an equal conclusion, reporting larger 𝑏 values for the eastern regions [27]. The qualitative data in Table 3 implies that the Reasenberg [3] and BC [12] are the most appropriate techniques suitable for determining the regional seismicity in the provinces.…”

Section: Resultssupporting

confidence: 88%

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A preliminary report on seismicity declustering methods and completeness magnitude in eastern Sunda Arc

Risanti

Realita

Fahmi

et al. 2022

J. Phys.: Conf. Ser.

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Data declustering separates mainshocks from both foreshocks and aftershocks while a reliable estimate of completeness magnitude is a key point in seismic parameter determination. These play a role in seismicity-related work. In this preliminary study, we reported seismicity in two Indonesian provinces, namely NTB and NTT, as part of eastern Sunda Arc using the USGS catalogue during 1970-2021 based on performance of three declustering methods (Gardner and Knopoff, Reasenberg, Uhrhammer). These methods were tested along with three techniques of M c determination (MAXC, EMR, BC) provided by ZMAP to estimate minimum magnitude cut-offs, leading to an accurate completeness magnitude. After careful examination, the Reasenberg and BC techniques were proved to be suitable for characterising seismicity in the regions of interest, where M c was calculated under a linear assumption of the cumulative frequency-magnitude distribution (FMD), widely known as the Gutenberg-Richter law. The results revealed that b and a parameters are influenced by the choice of a specific declustering algorithm and calculation of M c. NTT was found to have a higher level of seismicity than NTB and seismicity rates in the southern part of both provinces were higher than those in the northern part. However, the number of strong ground motion with M w ≥ 6.5 in the northern area was larger than that in the southern, indicating the potency of Flores Back-arc Thrust for generating large earthquakes hence possible tsunamis.

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Section: Resultssupporting

confidence: 88%

“…No best solution to 𝑀 c is available with no preliminary test; different techniques may give different 𝑀 c values after which care should be taken for the most appropriate 𝑀 c . The applied technique of 𝑀 c determination depends mainly on the characteristics of the regions of interest [13,14,15].…”

Section: Introductionmentioning

confidence: 99%

A preliminary report on seismicity declustering methods and completeness magnitude in eastern Sunda Arc

Risanti

Realita

Fahmi

et al. 2022

J. Phys.: Conf. Ser.

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“…Besaran 𝑀 c adalah parameter penting (Mignan and Woessner, 2012;Diantari et al, 2018) karena menjamin validitas keberlakuan relasi linier-logaritmik antara log 𝑁 dan 𝑀 (hukum Gutenberg-Richter) pada persamaan (1). Dalam hal ini, estimasi akurat 𝑀 c adalah penting karena 𝑀 c yang terlalu tinggi akan mereduksi jumlah data sedangkan 𝑀 c yang terlalu rendah akan menghasilkan 𝑎 dan 𝑏 yang menyimpang dari nilai semestinya (Mignan and Woessner, 2012).…”

Section: Magnitude Of Completenessunclassified

“…Tidak ada cara untuk memastikan bahwa nilai 𝑀 c yang diperoleh adalah benar absolut (Mignan and Woessner, 2012). Namun demikian, nilai 𝑀 c ≈ 5,0 untuk wilayah Indonesia masih bisa diterima (Diantari et al, 2018). Oleh karena akurasi 𝑀 c menentukan akurasi 𝑏 dan 𝑎, maka sensibilitas estimasi 𝑀 c bisa dilihat dari apakah nilai 𝑏 untuk masing-masing zona masuk akal atau tidak.…”

Section: Histogram Gempaunclassified

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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“…Formulasi untuk penentuan kedua parameter (a-value dan b-value) adalah hukum distribusi frekuensi-magnitudo Gutenberg-Richter yang diterapkan dalam berbagai kondisi tektonik dan sumber seismisitas (baik alami atau buatan). Studi kegempaan terdahulu dengan seting di luar wilayah Indonesia (Godano et al, 2014;Marzocchi et al, 2016;Hong et al, 2020) dan di Indonesia (Diantari et al, 2018) membahas variasi teknik penentuan a-value dan b-value.…”

Section: Pendahuluanunclassified

ESTIMASI PARAMETER a-VALUE DAN b-VALUE UNTUK ANALISIS STUDI SEISMISITAS DAN POTENSI BAHAYA BENCANA GEMPA TEKTONIK DI WILAYAH MALUKU UTARA

Risanti

Prastowo

2021

IFI

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Abstrak Studi seismisitas dan analisis potensi bahaya bencana seismik di wilayah Maluku Utara dapat dilakukan dengan menentukan parameter a-value dan b-value di wilayah tersebut. Kedua parameter mendiskripsikan level seismisitas dan akumulasi stres mekanik yang disimpan oleh batuan geologi bawah permukaan di wilayah tersebut. Secara prinsip, parameter a-value dan b-value ditentukan dari distribusi frekuensi-magnitudo gempa melalui hukum Gutenberg-Richter. Dalam penelitian ini, hukum Gutenberg-Richter diterapkan pada sumber gempa tektonik dari katalog gempa USGS (http://earthquake.usgs.gov/earthquakes/) selama 2009-2019 dengan kedalaman mencapai 551 km dan variasi magnitudo . Kedua parameter dihitung dengan metode least-squares dan maximum likelihood, di mana perbedaan signifikan a-value dan b-value menurut kedua metode tersebut merefleksikan level akurasi kedua metode tersebut. Metode maximum likelihood memberikan a-value dan b-value yang lebih akurat karena melibatkan penapisan data sebelum proses pengolahan data. Persamaan empiris Gutenberg-Richter yang diperoleh dari metode maximum likelihood adalah , di mana a = 9,73 dan b = 1,39 dengan adalah jumlah kejadian gempa dan adalah gempa dengan magnitudo lebih besar dari (batas bawah magnitudo di mana hukum Gutenberg-Richter berlaku valid). Analisis variasi spasial dan temporal b-value serta variasi spasial a-value berhasil merekonstruksi 3 kejadian gempa relatif besar antara 2009-2019. Kombinasi temuan b-value ≈ 1,4, a-value ≈ 9,7 dan a-value (annual) ≈ 8,7 dengan bantuan ZMAP6,0 menunjukkan bahwa seluruh wilayah Maluku Utara merupakan wilayah yang rentan terhadap bencana gempa dengan frekuensi gempa tinggi yang dipicu seismisitas relatif tinggi di wilayah tersebut. Temuan ini memicu peningkatan kesadaran dan kesiagaan terhadap potensi bahaya bencana gempa tektonik di Maluku Utara. Kata Kunci: seismisitas, bencana seismik, a-value, b-value, hukum Gutenberg-Richter Abstract Seismic studies and corresponding seismic hazard analysis in North Maluku can be performed using determination of a-value and b-value parameters. These parameters describe seismicity level and mechanical stress accumulated in subsurface structure in the region of interest. In principle, a-value and b-value were obtained from frequency-magnitude distribution provided by Gutenberg-Richter law. In this study, this law was generated using earthquake datasets from USGS at http://earthquake.usgs.gov/earthquakes/, where events occurred between 2009-2019 with varying magnitudes and depths to 551 km. The methods included the least-squares and maximum likelihood, where significant differences in the parameters acquired reflect levels of accuracy. The maximum likelihood method yielded accurate results for a-value and b-value due to data declustering prior to data processing. The Gutenberg-Richter law in a log-linear expression was obtained, where a = 9.73 and b = 1.39 with is the cumulative number of occurence and denotes events with magnitudes greater than (defined as the magnitude at which the lower end of the distribution starts to deviate from the Gutenberg-Richter law). Analysis of spatial and temporal variations of b-value and spatial variation of a-value successfully reconstructed 3 occurrences of large magnitudes during 2009-2019. A combined finding of b-value ≈ 1,4, a-value ≈ 9,7 dan a-value (annual) ≈ 8,7 by ZMAP6.0 found for North Maluku reveals that the whole parts of the region are vulnerable to tectonic earthquakes with high frequency owing to relatively high seismicity. This calls for increased awareness of and preparedness for possible seismic threats in North Maluku. Keywords: seismicity, seismic hazard, a-value, b-value, Gutenberg-Richter law

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Preliminary Magnitude of Completeness Quantification of Improved BMKG Catalog (2008-2016) in Indonesian Region

Cited by 9 publications

References 5 publications

A preliminary report on seismicity declustering methods and completeness magnitude in eastern Sunda Arc

A preliminary report on seismicity declustering methods and completeness magnitude in eastern Sunda Arc

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

ESTIMASI PARAMETER a-VALUE DAN b-VALUE UNTUK ANALISIS STUDI SEISMISITAS DAN POTENSI BAHAYA BENCANA GEMPA TEKTONIK DI WILAYAH MALUKU UTARA

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