Regional Moment Tensor Analysis in the Philippines: CMT Solutions in 2012–2013

2015 ◽  
Vol 10 (1) ◽  
pp. 18-24 ◽  
Author(s):  
Jun D. Bonita ◽  
◽  
Hiroyuki Kumagai ◽  
Masaru Nakano ◽  
◽  
...  
Keyword(s):  
Moment Tensor ◽  
The Philippines ◽  
Focal Mechanisms ◽  
Source Analysis ◽  
Centroid Moment Tensor ◽  
Large Size ◽  
Moment Tensor Analysis ◽  
Analysis System ◽  
Swift System ◽  
Seismographic Network

Recently, the Philippine Institute of Volcanology and Seismology (PHIVOLCS) has upgraded its seismic network, equipping it with accelerometers and broadband seismometers for intensity and focal mechanism determinations. As part of this upgrade, PHIVOLCS adapted the use of a source analysis system called SWIFT to determine the centroid moment tensor (SWIFT CMT). SWIFT CMT solutions were estimated for medium to large size earthquakes (4.1 ≤Mw≤ 7.6) in the Philippines for the period of January 2012 to November 2013 and were statistically evaluated with respect to the CMT solutions of the Global Centroid Moment Tensor (GCMT) Project. The seismic moments, moment magnitudes, centroid locations, depths and focal mechanisms of most of the SWIFT CMT solutions are found to be consistent to those of the GCMT solutions for earthquakes withMw≥ 4.6. The SWIFT system with the new broadband seismographic network provides more CMT solutions for moderate size earthquakes (Mw≥ 4.1) than GCMT. SWIFT proves to be useful in the development of the Philippines CMT catalogue that will lead to a better understanding of seismotectonics in the Philippines.

Development and Operation of a Regional Moment Tensor Analysis System in the Philippines: Contributions to the Understanding of Recent Damaging Earthquakes

2015 ◽  
Vol 10 (1) ◽  
pp. 25-34 ◽  
Author(s):  
Baby Jane T. Punongbayan ◽  
◽  
Hiroyuki Kumagai ◽  
Nelson Pulido ◽  
Jun D. Bonita ◽  
...  
Keyword(s):  
Moment Tensor ◽  
Waveform Inversion ◽  
The Philippines ◽  
Tensor Analysis ◽  
Philippine Sea Plate ◽  
Source Analysis ◽  
Source Information ◽  
Centroid Moment Tensor ◽  
Moment Tensor Analysis ◽  
Analysis System

A network of 10 satellite-telemetered broadband stations was established under a cooperative project between Japan and the Philippines, and a source analysis system based on waveform inversion of regional seismograms was adapted to operationalize a regional moment tensor analysis of Philippine earthquakes. This study presents the source information generated by the system for recent damaging earthquakes: theMw6.7 Negros andMw7.6 offshore Samar in 2012, and theMw7.2 in Bohol in 2013. Results show that the Negros event was generated by shallow NE–SW thrust faulting with a small strike-slip component, and that the centroid was located slightly offshore. The Samar event occurred in relation to an outer-trench thrust fault within the Philippine Sea Plate, adjacent to a part of the Philippine Trench that has relatively low seismicity. Our centroid moment tensor (CMT) solutions show that the Samar event triggered distinct clusters of outer-rise normal and thrust aftershocks, which we explain as being consistent with a Coulomb stress change in the area. Finally, we infer that the previously unidentified fault zone that generated the Bohol earthquake has a length of ∼ 100 km, is oriented ENE–WSW, transects parts of Bohol, and extends offshore towards Cebu. These examples show how recent improvements in Philippine earthquake monitoring could contribute to the characterization of earthquake sources and in the understanding of the seismotectonics of the area.

scholarly journals Analisis Potensi Tsunami Menggunakan Mekanisme Fokus (Studi Kasus Gempa 15 November 2014

Jurnal MIPA ◽  
2018 ◽  
Vol 7 (1) ◽  
pp. 12
Author(s):  
Aprillya J.G Arikalang ◽  
Guntur Pasau ◽  
Ferdy _
Keyword(s):  
Empirical Formula ◽  
Moment Tensor ◽  
Ocean Floor ◽  
Tensor Analysis ◽  
Surrounding Area ◽  
Centroid Moment Tensor ◽  
Regional Seismicity ◽  
North Sulawesi ◽  
Source Data ◽  
Moment Tensor Analysis

Lempeng laut Maluku merupakan lempeng mikro yang berada di antara lempeng mikro Sangihe dan Halmahera yang bergerak berlawanan arah, kondisi ini mengakibatkan kegempaan daerah Sulawesi Utara dan sekitarnya terkonsentrasi di sebagian besar wilayah Laut Maluku dan sisanya terjadi di Laut Sulawesi. Adapun tujuan penelitian ini adalah untuk menentukan karakterisik pola patahan akibat gempabumi tanggal 15 November 2014 di Laut Maluku koordinat 10 LS – 30 LU dan 1200 - 1300 BT dengan sumber data dari katalog gempa bumi USGS dan Global Centroid Momen Tensor. Analisis bola fokus bahwa gempa tanggal 14 November 2014 dengan koordinat 10 LS – 30 LU dan 1200 - 1300 BT adalah kombinasi sesar mendatar dan sesar naik atau jenis sesar ini disebut juga oblique. Hasil analisis menggunakan Sofware WinITDB dan perhitungan rumus empiris menunjukkan bahwa terjadi deformasi di dasar laut 1,409 m, yang menyebabkan terjadinya Tsunami yang kecil, karena deformasi yang terjadi belum cukup kuat pengaruhnya untuk merobek permukaan dasar laut.Molucca Sea plate is the plate between the micro’s plate Sangihe and Halmahera are moving in opposite directions, these conditions result in the regional seismicity of North Sulawesi and the surrounding area is largely concentrated in the Molucca sea and the rest occur in the Celebes Sea. As for the purpose of this research is to determine the result of fracturing pattern karakterisik gempabumi November 15, 2014 in the Molucca sea coordinates 10 LS – 30 N and 1200-1300 BT with the source data from the USGS earthquake catalogs and the Global Centroid Moment Tensor. Analysis of the focal sphere that the earthquake on 14 November 2014 with coordinates 10 LS – 30 N and 1200-1300 BT is a combination of horizontal fault and fault ride or any type of fault is also called oblique. The results of the analysis using WinITDB Software and calculation of empirical formula indicate that occurs on the ocean floor deformation 1.409 m, which led to a small Tsunami, because deformations that occur are not yet strong enough to rip his influence the surface of the seabed.

Regional Centroid-Moment-Tensor Analysis for Earthquakes in Canada and Adjacent Regions: An Update

2012 ◽  
Vol 83 (3) ◽  
pp. 505-515 ◽  
Author(s):  
H. Kao ◽  
S.-J. Shan ◽  
A. Bent ◽  
C. Woodgold ◽  
G. Rogers ◽  
...  
Keyword(s):  
Moment Tensor ◽  
Tensor Analysis ◽  
Centroid Moment Tensor ◽  
Moment Tensor Analysis

scholarly journals The Reliance of the Earthquake B-Value on Depth and Focal Mechanism

2021 ◽  
Vol 54 (1D) ◽  
pp. 1-10
Author(s):  
Emad Al-Heety
Keyword(s):  
Moment Tensor ◽  
Focal Depth ◽  
Seismic Hazard Assessment ◽  
B Value ◽  
Strike Slip ◽  
Focal Mechanisms ◽  
Likelihood Method ◽  
Centroid Moment Tensor ◽  
B Values ◽  
Completeness Magnitude

The earthquake size distribution (b-value) is a significant factor to recognize the seismic activity, seismotectonic, and seismic hazard assessment. In the current work, the connection of the b-constant value with the focal depth and mechanism was studied. The effect of the study scale (global, regional and local) on the dependence of b-value on the focal mechanisms was investigated. The database is quoted from the Global Centroid Moment Tensor catalog. The selected earthquakes are the shallow normal, reverse and strike-slip events. The completeness magnitude (Mc) is 5.3. The maximum likelihood method is utilized to compute the b-value. The obtained results show that the b-value is decreasing with depth to range 10-20 km, then increases to the depth of 40km. The turning point of b-value (increasing of b-value) locates at the depth of the transition brittle-ductile zone. Globally and regionally, low, moderate, and high b-values are associated with reverse, strike-slip, and normal focal mechanisms, respectively, while locally, the relation between b-values and focal mechanisms shows different association trends, such as low, moderate, and high b-values are associated with normal, strike-slip, and reverse focal mechanisms and so on.

A Testable Worldwide Earthquake Faulting Mechanism Model

2021 ◽  
Author(s):  
Matteo Taroni ◽  
Jacopo Selva
Keyword(s):  
Simple Model ◽  
Moment Tensor ◽  
A Priori ◽  
Testing Procedure ◽  
Global Scale ◽  
Focal Mechanisms ◽  
Source Inversion ◽  
Source Characterization ◽  
Centroid Moment Tensor ◽  
Mechanism Model

Abstract In this article, we present a simple model to forecast global focal mechanisms. This model is based on a simple discrete counting distribution of the global centroid moment tensor catalog, and it also includes, using a Bayesian scheme, the a priori information from the Anderson theory of faulting. Our model is tested in hindcasting mode against independent data of global large earthquakes with Ms≥7. We obtained statistically significant good agreement between model and data using consistency test, demonstrating that this simple model can satisfactorily forecast focal mechanisms at the global scale. The defined testing procedure can be used to test the model in prospective mode against future events. These forecasts may inform short- to long-term hazard quantifications that require a finite source characterization, as well as real-time source inversion algorithms.

All Source Analysis System (ASAS). Block 1. Abbreviated HARDMAN analysis. Appendices to Volume 1

1992 ◽  
Author(s):  
James C. Whitfield ◽  
Kimball R. Stuhlmuller ◽  
Scott A. Jashinski ◽  
Edward Burke ◽  
Dean DeVault
Keyword(s):  
Source Analysis ◽  
Analysis System
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