Earthquake relocation

Penelitian mengenai Area Geothermal Kamojang telah banyak dilakukan, namun dari sekian penelitian
tersebut hanya berfokus pada metode gravity. Pada penelitian ini metode yang digunakan untuk monitoring
Area Geothermal Kamojang adalah metode MEQ (Micro-Earthquake) dengan tujuan memperoleh sebaran
hiposenter menggunakan metode penentuan hiposenter SED (Single Event Determination). Gempa mikro
pada suatu area geothermal disebabkan oleh adanya zona lemah yang terbuka akibat injeksi air, zona
tersebut akan semakin terbuka seiring pertambahan volume, laju, dan tekanan air reinjeksi, adanya kontak
antara air dingin dengan batuan reservoir yang panas maupun heat-source, serta berkurangnya pori batuan
akibat hilangnya fluida pengisi peori tersebut sebagai dampak aktivitas produksi. Karakteristik gempa mikro
yaitu memiliki magnitudo 􀂔 3 SR (Skala Richter) serta durasi gempanya yang tidak akan lebih dari satu menit.
Metode penentuan hiposenter gempa yang dikembangkan oleh Geiger (1910) yaitu metode SED merupakan
sebuah proses iterasi dengan optimasi Gauss-Newton untuk menentukan lokasi sumber gempa bumi.
Metode tersebut merupakan pemodelan ke depan dengan tujuan meminimalkan nilai travel time residual
antara arrival time yang teramati dengan arrival time yang diprediksi atau hasil pemodelan. Dari pengolahan
data rekaman gempa selama bulan April – Mei 2014, diperoleh 56 events/kejadian gempa mikro dengan
rincian terdapat 39 events yang memiliki magnitudo gempa 0,1 SR, 14 events dengan magnitudo 0,2 SR, 2
events 0,3 SR, serta 1 events magnitudo 0,4 SR. Mayoritas hiposenter gempa yang diperoleh dari
pengolahan data ternyata berada di luar Area Geothermal Kamojang.

Preventive resettlement of communities from extremely hazard prone areas would result in large quantitative gains in global disaster resilience, reduce annual global recovery spending, and prevent disaster events from impacting on hard won development gains. Prevention as opposed to recovery has become the norm in describing a smart approach to disaster management yet preventive resettlement, requiring action before a significant event, is rarely considered as part of national disaster management strategies. This article describes why it is underutilised and how it could be employed more systematically to reduce risk in the most hazard prone areas in countries such as the Philippines. The Paper describes how the poor global track record of development induced displacement and resettlement (DIDR) has inadvertently impacted on perceptions of resettlement in general and considers how preventive resettlement fits within current theoretical models, proposing a distinct model for preventive resettlement.

The area around Sinai Peninsula (including Gulf of Aqaba, Gulf of Suez, and Northern Red Sea) is considered as the most active seismic region due to its complicated geologic structures. In this area, the recent seismic activity for a period from 1997 to 2014 (1445 events) recorded by the Egyptian National seismic network (ENSN), the Saudi Arabia seismic network (SASN) and some stations located in Palestine have been relocated. Three techniques were applied for improving the seismicity locations, least square method, the Wadati diagram method, and the Probability method for the determination of earthquake epicenters. Since the waveforms of the ENSN were available, re-picking for the seismic phases was implemented via least square method to minimize the time residuals of the picked seismic phases. For the all seismic data used, physical tests for the arrivals of the P and S phases was performed using the Wadati method to obtain more reliable phase picking. The final locations were obtained using the Hypoinverse program, applying the Probability method for the determination of earthquake epicenters. The average horizontal dislocation in epicenters was measured at ~13 Km, the average Vertical dislocation in Hypocenters was ~8 Km. The relocations have been improved and revealed cluster of seismic activity around the triple junction area, particularly at the opining areas of Gulf of Suez and Gulf of Aqaba. The relocated seismicity was centered on the active faults cutting the study area. When compared with previous studies conducted on the same area, our results give good locations of seismic activity relate to the tectonic setting of the study region, since more arrivals of different networks were used. The output of this study is considered a new contribution for further seismic hazard studies by providing a more precise seismic catalogue of the instrumentally recorded events in the study region from 1997 to 2014. Hence this provided catalogue may use for any other seismological applications in future. Seismicity Relocations around the Sinai Peninsula, northeast of Egypt: Contribution of regional seismic networks. N Y Sci J 2017;10(4):37-50]. ISSN 1554-0200 (print); ISSN 2375-723X (online). http://www.sciencepub.net/newyork. 5.

The accuracy of earthquake hypocenter position is necessary to analyze the tectonic conditions. This study aims to: (1) relocate the mainshock and aftershocks of the large earthquakes in Papua region i.e. June 16, 2010, April 21, 2012 and April 06, 2013 earthquake (2) determine the true fault plane, (3) estimate the area of the fracture, and (4) analyze the advantages and disadvantages of relocation with MJHD method in benefits for tectonic studies. This study used Modified Joint Hypocenter Determination (MJHD) method. Using P arrival phase data reported by the BMKG and openly available from website repogempa.bmkg.go.id, we relocated the mainshock of this large significant earthquakes and its aftershocks. Then we identified the preffered fault planes from the candidate fault planes provided by the global CMT catalogue. The position of earthquakes was successfully relocated. The earthquakes mostly was clustered around the mainshock. Earthquakes that not clustered around mainshock are considered to be different mechanism from the mainshock. Relocation results indicate that the mainshock fault plane of June 16, 2010 earthquake is a field with strike 332, dip 80 and -172 slip, the mainshock fault plane of April 21, 2012 earthquake is a field with strike 82, dip 84 and 2 slip, the mainshock fault plane of April 06, 2013 earthquake is a field with strike 339, dip 56 and -137 slip. Fault plane area estimated by cross section graphical method is an area of 2816.0 km^2 (June 16, 2010), 906.2 km^2 (April 21, 2012) and 1984.3 km^2 (April 06, 2013).
MJHD method has the advantage that it can calculate a lot of earthquakes simultaneously and has a station correction to account for lateral heterogeneity of the earth. This method successfully provides significant changes to improve the position of the depth of earthquakes that most of the hypocenter depth manually specified as a fixed depth (± 10 km). But this method cannot be sure that the hypocenters derived from the same earthquake mechanism. Keywords: hypocenter relocation, mjhd method, northern Papua earthquakes

In this study phase data from the Cornet seismological network installed by the Geophysics-Geothermics Department (University of Athens) and the permanent networks of the Geodynamic Institute of the National Observatory of Athens and of the Geophysics Department of Thessaloniki (Aristotle University), for the decade 1996-2006, were merged. The data were jointly used to relocate the earthquakes that occurred in the broader area of Greece. Initially, single-event algorithms were applied by minimizing spatiotemporal residuals. Following, the hypocenters were relocated using a doubledifference algorithm where rms, as well as the horizontal and vertical location errors (erh, erz) were minimized and a consequence of that better locations were achieved. After that process the spatial distribution of the epicenters outlined major local tectonic features in Greece. Moreover, the same methodology was applied to the aftershock sequences of large earthquakes and the results were successfully co...

We successfully revealed the refined seismicity near Mt. Pandan which occurred on February 2016 adopting waveform cross-correlation technique. Mt. Pandan seismic sequence is very interested since there were some earthquakes occurred in June 2015 and also seismic swarm in February 2016. Cross-correlation values are necessary to be used in double-difference relocation due to providing more reliable travel time differential data. About 65 events is relocated using 27 channels came from 9 seismic stations of BMKG. We provided more precisely hypocenters because the P and S phases are manually hand-picked. Seismicity pattern more precisely shows lineation which is elongated and deeper in west-east direction (10-20 km) and has no correlation with thrusting fault on the north side Mt.pandan otherwise strongly expected was related to strike-slip fault in the northeast Klangon, near Mt. Pandan.

We successfully revealed the refined seismicity near Mt. Pandan which occurred on February 2016 adopting waveform cross-correlation technique. Mt. Pandan seismic sequence is very interested since there were some earthquakes occurred in June 2015 and also seismic swarm in February 2016. Cross-correlation values are necessary to be used in double-difference relocation due to providing more reliable travel time differential data. About 65 events is relocated using 27 channels came from 9 seismic stations of BMKG. We provided more precisely hypocenters because the P and S phases are manually hand-picked. Seismicity pattern more precisely shows lineation which is elongated and deeper in west-east direction (10-20 km) and has no correlation with thrusting fault on the north side Mt.pandan otherwise strongly expected was related to strike-slip fault in the northeast Klangon, near Mt. Pandan.