Anomalous Seismicity and Earthquake Forecast in Western Nepal Himalaya and its Adjoining Indian Region

Singh, Harendra; Paudyal, Harihar; Shanker, D.; Panthi, Ananta; Kumar, Ashutosh; Singh, Vijay Pratap

doi:10.1007/s00024-010-0072-6

Cited by 10 publications

(8 citation statements)

References 28 publications

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“…Dengan menggunakan solusi regresi linier berbobot, parameter model (m 1 dan m 2 ) dapat diselesaikan dengan persamaan: Singh [19] juga meneliti pola atau karakteristik kegempaan sebelum terjadi gempabumi signifikan di daerah Barat Nepal, India. Berdasarkan hasil penelitian ini, karakteristik kegempaan di wilayah Nepal terdapat pola yang menarik yaitu selalu diikuti dengan siklus kegempaan yang terdiri dari siklus normal (N), anomali seismisitas atau peningkatan aktivitas seismisitas (swarm) (A), penurunan aktivitas seismik (precursory gap) (G), dan diikuti gempabumi utama.…”

Section: B Teori Tentang Regresi Model Perkiraan Magnitudounclassified

“…Artinya dugaan besarnya magnitudo gempabumi utama bisa dihitung jika siklus kegempaan pada periode swarm telah dilewati sebelum terjadinya gempabumi utama. Menurut Singh [19] kondisi ini hanya berlaku jika pada masa siklus senyap atau penurunan aktivitas kegempaan tidak ada gempabumi dengan magnitudo lebih besar atau sama dengan magnitudo M p . Dengan adanya magnitudo yang lebih besar atau sama dengan M p pada saat periode precursory gap berarti akan mengurangi akumulasi stress pada patahan.…”

Section: Regresi Formula Perkiraan Magnitudo Gempabumi DI Wilayah Benunclassified

“…Dengan adanya magnitudo yang lebih besar atau sama dengan M p pada saat periode precursory gap berarti akan mengurangi akumulasi stress pada patahan. Kondisi ini akan memperpanjang siklus precursory gap yang akan mengakibatkan peluang terjadinya gempabumi utama (M m ) dengan magnitudo yang lebih besar [19] . Jika kondisi ini terjadi maka diperlukan pertimbangan dan faktor lain untuk mengestimasi besarnya magnitudo gempabumi utama (M m ).…”

Section: Regresi Formula Perkiraan Magnitudo Gempabumi DI Wilayah Benunclassified

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Siklus dan Model Perkiraan Kejadian Gempabumi di Daerah Bengkulu

Ardiansyah¹

2014

JFA

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IntisariSebelum terjadi gempabumi utama, biasanya akan didahului oleh suatu pola atau siklus kegempaan. Siklus ini meliputi periode normal, periode anomali yang ditandai dengan peningkatan aktivitas, periode precursory gap yang ditandai dengan penurunan aktivitas seismik, dan periode terjadinya gempabumi utama. Tujuan dari penelitian ini adalah untuk melihat siklus kegempaan serta model (persamaan) perkiraan terjadinya gempabumi di wilayah Bengkulu untuk kegunaan mengestimasi besarnya magnitudo gempabumi yang akan terjadi berdasarkan model yang dibuat. Data yang digunakan adalah katalog data kegempaan M > 4,5 di daerah Bengkulu pada rentang tahun 1971-2013 yang diambil melalui website USGS. Metode yang digunakan untuk perhitungan model perkiraan magnitudo gempabumi menggunakan metode Predictive Regressions dengan perhitungan regresi linier berbobot. Berdasarkan hasil analisis, model yang sudah dibuat menunjukkan bahwa diperkirakan saat ini daerah Bengkulu memilki potensi gempabumi dengan kekuatan M > 7,5 dengan siklus kegempaan daerah Bengkulu memasuki periode precursory gap yang ditandai dengan penurunan aktivitas kegempaan. ABSTRACTBefore a major earthquake occurs, it will usually be preceded by a pattern or cycle of seismicity . This cycle includes a period of normal , anomalous period marked by increased activity , precursory gap period is characterized by a decrease in seismic activity , and the period of occurrence of major earthquakes . The purpose of this study is to look at seismic cycle and the model ( equation ) estimates the occurrence of earthquakes in the region for the purposes of estimating the Bengkulu earthquake magnitude that will occur based on the model created . The datas used is a catalog of seismic data for M > 4.5 in the Bengkulu area in the range of 1971 to 2013 were taken through the USGS catalog. The method used to estimate the magnitude of an earthquake model calculations using the predictive regressions with weighted linear regression calculation. Based on the analysis, a model that has been made indicates that the current estimated Bengkulu area have the potential earthquake with the strength of M > 7.5 seismicity cycle Bengkulu area entered a period of precursory gap is characterized by a decrease in seismic activity .KATA KUNCI: Earthquake cycle, precursors, earthquake forecast models I. PENDAHULUANBeberapa prekursor gempabumi seperti deformasi kerak bumi, perubahan level muka air laut, regangan, tegangan kerak bumi, gempabumi pendahuluan, anomali aktivitas kegempaan, gempabumi swarm, b value, perubahan kecepatan gelombang seismik, perubahan air tanah, dan gas radon merupakan fenomena yang terjadi sebagai pendahuluan sebelum terjadinya gempabumi besar [1,2]. Fenomena prekursor gempabumi bisa berbeda antara satu daerah dengan daerah lain [3], hal ini terjadi karena adanya perbedaan struktur geologi tiap daerah. Beberapa penelitian menunjukkan, fluktuasi perubahan aktivitas seismisitas berhubungan erat se- * E-MAIL: sabar.ardiansyah@bmkg.go.id bagai indikator prekursor gempabumi. A...

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Section: B Teori Tentang Regresi Model Perkiraan Magnitudounclassified

Section: Regresi Formula Perkiraan Magnitudo Gempabumi DI Wilayah Benunclassified

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Siklus dan Model Perkiraan Kejadian Gempabumi di Daerah Bengkulu

Ardiansyah¹

2014

JFA

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“…This is an indication that a possibly wider area will be placed at risk and revised estimates for magnitude and time of occurrence of the main shock may be necessary. Several authors (Bufe et al, 1977;Gupta and Singh, 1989;Shanker et al 2010;Singh et al 2010) have reported changes in seismicity patterns before the occurrence of medium to large earthquakes. Gupta and Singh (1986) observed that it is important to recognise swarm and quiescence before the occurrence of the main shock and made successful prediction of 06 August, 1988 Indo-Burma border earthquake.…”

Section: Precursor and Earthquake Forecastingmentioning

confidence: 99%

Discourse on Seismotectonics of Nepal Himalaya and Vicinity:Appraisal to Earthquake Hazard

Shanker¹,

Paudyal²,

Singh³

2012

GEO

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An extremely complex geotectonic framework coupled with high seismic status has made the Central part of the Himalayas, a destination to study the complex inter-continental collision processes. The collision also caused large scale deformation and high seismicity of vast region of colliding continents. This region displays all major tectonic features of the Himalayan mobile belt and is seismically one of the active regions in the Himalayan arc. Focal mechanism solutions bear out a multifaceted pattern. Thrust environment is dominant in the Western and Central Nepal region, whereas, in the Eastern Nepal, it is a amalgamation of thrust and strike-slip with large thrust mechanism. In western region thrust faulting coupled with shallow dip nodal planes reflects the Indian lithosphere is under-thrusting at a shallow angle. Here, the crustal shortening in north-south direction in which earthquakes is generated due to northward compression. The shortening was accommodated by development of various NW-SE trending structures like Himalayan Arc MCT (Main Central Thrust), MBT (Main Boundary Thrust); MFT (Main Frontal Thrust). The observed change in the faulting pattern in the eastern parts of the thrust zone may indicate substantial movement along the transverse faults, as compared to that of the western region with the changes in the deep crustal structure. The thrusting decreases rapidly with increasing focal depth and deformation occur due to strike-slip motion at greater depths. This may investigative of an unstable state of the upper mantle leading to a rapid deformation in the presence of high degree of thermal regime. The composite stereographic projection of the compression and tension axes suggest a shallow compressive stress, dipping N-S to NE-SW in Western Nepal whereas it is N-S to NNE-SSW direction of compression at a shallow angle in Eastern Nepal. The region produced a number of devastating events in the past. Central Himalaya comprising Nepal and its adjoining region in which different types of faulting patterns exist have signatures of a great earthquake in 1934 and a number of large events thereafter, advocate serious seismic hazard in the region.

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“…This is an indication that a possibly wider area will be placed at risk and revised estimates for magnitude and time of occurrence of the mainshock may be necessary. Several authors (Bufe et al, 1974;Sekiya, 1976;Gupta and Singh, 1989;Zheng et al, 1995;Shanker et al, 2010;Singh et al, 2010) have reported changes in seismicity patterns before the occurrence of medium to large earthquakes. Gupta and Singh (1986) observed that it is important to recognise swarm and quiescence before the occurrence of the mainshock and made successful prediction of 06 August, 1988 Indo-Burma border earthquake.…”

Section: Introductionmentioning

confidence: 95%