Seismisitas di Wilayah Jawa Tengah dan Sekitarnya Berdasarkan Hasil Relokasi Hiposenter dari Empat Jaringan Seismik Menggunakan Model Kecepatan 3-D

ABSTRAK Relokasi hiposenter merupakan suatu metode yang digunakan untuk mendapatkan parameter-parameter gempa yang presisi. Parameter-parameter tersebut digunakan untuk studi tektonik lanjut seperti seismic hazard assessment pada suatu area. Penggunan model kecepatan 3-D secara teori akan memberikan hasil yang lebih baik dibandingkan dengan model 1-D karena model kecepatan di bawah permukaan bumi lebih mendekati model 3-D. Sebanyak 767 event gempa yang direkam oleh jaringan seismik DOMERAPI, MERAMEX, BMKG, dan BPPTKG digunakan pada penelitian ini. Gempa-gempa tersebut direlokasi dengan model kecepatan 3-D dan dianalisis untuk studi seismotektonik di wilayah Jawa Tengah dan sekitarnya. Hasil relokasi hiposenter menggunakan model kecepatan 3-D berhasil mendeteksi sejumlah fitur tektonik secara lebih jelas seperti struktur kolom yang berkaitan dengan Struktur backthrust di selatan Kebumen. Penampang vertikal arah barat-timur yang melewati Sesar Opak mengindikasikan arah dip bidang sesarnya ke arah timur. Zona seismik ganda yang terdeteksi pada studi sebelumnya tidak bisa teridentifikasi dengan baik pada studi ini. Sejumlah gempa volcano-tectonic (VT) berkaitan dengan aktivitas magma dangkal Gunung Merapi terdeteksi juga dengan jelas pada studi ini.ABSTRACT Hypocenter relocation is a method used to get precise earthquake parameters. They will be useful for an advanced tectonic study like seismic hazard assessment in an area. The hypocenter relocation using a 3-D velocity model will theoretically obtain better results than a 1-D velocity model because the earth subsurface model is closed with a 3-D model. Some 767 earthquakes recorded by DOMERAPI, MERAMEX, BMKG, and BPPTKG networks used in this research. They were relocated by using a 3-D velocity model and analyzed for seismotectonic study in Central Java area and its surroundings. The result of hypocenter relocation using a 3-D velocity model is successfully detecting some tectonic features more clearly like columnar structure related to the backthrust structure at the south of Kebumen. The west-east vertical cross-section crossing the Opak fault indicates the dip of the fault plane is directing to the east. This study could not identify the double seismic zone, which was detected by the previous research. Some volcano-tectonic (VT) earthquakes related to the shallow magma activity of Mount Merapi also are detected clearly in this study.

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A detailed seismic zonation model for shallow earthquakes in the broader Aegean area

Natural Hazards and Earth System Sciences Discussions ◽

10.5194/nhessd-1-6719-2013 ◽

2013 ◽

Vol 1 (6) ◽

pp. 6719-6784 ◽

Cited By ~ 3

Author(s):

D. A. Vamvakaris ◽

C. B. Papazachos ◽

C. Papaioannou ◽

E. M. Scordilis ◽

G. F. Karakaisis

Keyword(s):

Seismic Hazard ◽

Hazard Assessment ◽

Active Faults ◽

Seismic Hazard Assessment ◽

Maximum Magnitude ◽

Seismic Zone ◽

Seismic Zonation ◽

Aegean Area ◽

Seismic Zones ◽

Shallow Earthquakes

Abstract. In the present work we present an effort to define a new seismic zonation model of area type sources for the broader Aegean area, which can be readily used for seismic hazard assessment. The definition of this model is based not only on seismicity information but incorporates all available seismotectonic and neotectonic information available for the study area, in an attempt to define zones which show not only a rather homogeneous seismicity release but also exhibit similar active faulting characteristics. For this reason, all available seismological information such as fault plane solutions and the corresponding kinematic axes have been incorporated in the analysis, as well as information about active tectonics, such as seismic and active faults. Moreover, various morphotectonic features (e.g. relief, coastline) were also considered. Finally, a revised seismic catalogue is employed and earthquake epicentres since historical times (550 BC–2008) are considered, in order to define areas of common seismotectonic characteristics, that could constitute a discrete seismic zone. A new revised model of 113 earthquake seismic zones of shallow earthquakes for the broader Aegean area is finally proposed. Using the proposed zonation model, a detailed study is performed for the catalogue completeness for the recent instrumental period. Using the defined completeness information, seismicity parameters (such as G–R values) for the 113 new seismic zones have been calculated, and their spatial distribution was also examined. The spatial variation of the obtained b values shows an excellent correlation with the geotectonic setting in the area, in good agreement with previous studies. Moreover, a quantitative estimation of seismicity is performed in terms of the mean return period, Tm, of large (M ≥ 6.0) earthquakes, as well as the most frequent maximum magnitude, Mt, for a typical time period (T = 50 yr), revealing significant spatial variations of seismicity levels within the study area. The new proposed seismic zonation model and its parameters can be readily employed for seismic hazard assessment for the broader Aegean area.

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Probabilistic Seismic Hazard Assessment of Sudan and Its Vicinity

Earthquake Spectra ◽

10.1193/1.1586181 ◽

2001 ◽

Vol 17 (3) ◽

pp. 399-415 ◽

Cited By ~ 8

Author(s):

Jamal A. Abdalla ◽

Yahia E-A. Mohamedzein ◽

A. Abdel Wahab

Keyword(s):

Seismic Hazard ◽

Hazard Assessment ◽

Seismic Activity ◽

Probabilistic Approach ◽

Seismic Hazard Assessment ◽

Seismic Source ◽

Probabilistic Seismic Hazard Assessment ◽

Seismic Zone ◽

Ground Acceleration ◽

Grid Points

This paper presents seismic hazard assessment and seismic zoning of Sudan and its vicinity based on probabilistic approach. The area studied lies between 22° E- 45° E and 0° - 24° N. Tectonics of Sudan and its vicinity is first reviewed. An updated NOAA catalogue, containing both historical and instrumental events and covering the period from 700 A.D. to 1993 is then used. Seismic source regions are modeled and relationships between earthquake magnitude and earthquake frequency are established. A modified attenuation relation is used. Seismic hazard assessment is then carried out for 60 km interval grid points. Seismic hazard maps of the studied area based on peak ground acceleration (PGA) for 10% probability of exceedance for time-spans of 50, 100, 200 and 250 years are presented. The results showed that the PGA ranges from 0.02g for low seismic activity regions to around 0.62g for high seismic activity regions. A seismic zone map is also shown for 475 years return period.

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A detailed seismic zonation model for shallow earthquakes in the broader Aegean area

Natural Hazards and Earth System Science ◽

10.5194/nhess-16-55-2016 ◽

2016 ◽

Vol 16 (1) ◽

pp. 55-84 ◽

Cited By ~ 10

Author(s):

D. A. Vamvakaris ◽

C. B. Papazachos ◽

Ch. A. Papaioannou ◽

E. M. Scordilis ◽

G. F. Karakaisis

Keyword(s):

Seismic Hazard ◽

Hazard Assessment ◽

Active Faults ◽

Seismic Hazard Assessment ◽

Maximum Magnitude ◽

Seismic Zone ◽

Seismic Zonation ◽

Aegean Area ◽

Seismic Zones ◽

Shallow Earthquakes

Abstract. In the present work we propose a new seismic zonation model of area type sources for the broader Aegean area, which can be readily used for seismic hazard assessment. The definition of this model is based not only on seismicity information but incorporates all available seismotectonic and neotectonic information for the study area, in an attempt to define zones which show not only a rather homogeneous seismicity release but also exhibit similar active faulting characteristics. For this reason, all available seismological information such as fault plane solutions and the corresponding kinematic axes have been incorporated in the analysis, as well as information about active tectonics, such as seismic and active faults. Moreover, various morphotectonic features (e.g. relief, coastline) were also considered. Finally, a revised seismic catalogue is employed and earthquake epicentres since historical times (550 BC–2008) are employed, in order to define areas of common seismotectonic characteristics, that could constitute a discrete seismic zone. A new revised model of 113 earthquake seismic zones of shallow earthquakes for the broader Aegean area is finally proposed. Using the proposed zonation model, a detailed study is performed for the catalogue completeness for the recent instrumental period.Using the defined completeness information, seismicity parameters (such as G–R values) for the 113 new seismic zones have been calculated, and their spatial distribution was also examined. The spatial variation of the obtained b values shows an excellent correlation with the geotectonic setting in the area, in good agreement with previous studies. Moreover, a quantitative estimation of seismicity is performed in terms of the mean return period, Tm, of large (M  ≥  6.0) earthquakes, as well as the most frequent maximum magnitude, Mt, for a typical time period (T  =  50 yr), revealing significant spatial variations of seismicity levels within the study area. The new proposed seismic zonation model and its parameters can be readily employed for seismic hazard assessment for the broader Aegean area.

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