adisorn foongkajorn chiang mai seismic station. abstract a drop of number of seismicity is a seismic...
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Adisorn FoongkajornChiang Mai Seismic Station
Abstract A drop of number of seismicity is a seismic precursor (Bath,1979). During 1960-2005, earthquakes in Sumatra-Andaman seismic belt had occurred continually. After deployment of the World Wide Standardized Seismograph Network (WWSSN) in 1960’s, instrumentally seismic data of the region has been collected systematically. According to this study more than 3000 of the earthquakes of magnitude 5 in the Sumatra-Andaman seismic belt were analyzed and mapped. About 10% decline of seismicity was found in 1990’s. Then the most destructive event of the region occurred on 26 December 2004 with consequently high seismicity.
Scope of the study
http://elvis.engr.wisc.edu/UER/uer96/author3/fig2.gif
SeismicPrecursors
Seismic precursors- Decreasing Vp/Vs (10-20% change) Electrical resistivity (15% change) Number of seismicity
- Increasing (geodetic measurements) Tilt Vertical motion Volumetric strain
(Bath, 1979:298)
First Episode of the Great Sumatra Earthquake
Indian Plate that has played an important roll in the Sumatra-Andaman Seismic Belt
Panoramic Scene of the Sumatra-Andaman seismic belt
Origin of Volcanic Island Arc as Andaman and Nicobar were originated
Epicentral Distribution in Sumatra-Andaman seismic belt during 1960-2005
Epicentral Distribution in Sumatra-Andaman seismic belt during 1960-2005
Number of the Earthquakes in Sumatra-Andaman Seismic Belt during 1960-2005
Year No. Change(%)
1960-1969 259
1970-1979 *
541 + 108.88
1980-1989 585 + 8.13
1990-1999 529 - 9.57
2000-2005 1238 +134.03
* Development of highly sensitive seismograph
Total 3152
Number of the Earthquakes in Sumatra-Andaman Seismic Beltduring 1960-2005
Magnitude Number 9 1 8 1 7 17 6 186 5 2947
Magnitude of the Earthquakes in Sumatra-Andaman seismic beltduring 1960-2005
Total 3152
Magnitude of the Earthquakes in Sumatra-Andaman seismic beltduring 1960-2005
Depth Distribution of the Earthquakes in Sumatra-Andaman seismic beltduring 1960-2005
Cumulative Depth Distribution of the Earthquakes in Sumatra-Andaman seismic belt during 1960-2005
1960-1969 1960-1979
1960-1989 1960-1999
1960-2005
Cumulative Depth Distribution of the Earthquakes in Sumatra-Andaman seismic belt during 1960-2005
Depth Contour of the Earthquakes in Sumatra-Andaman seismic belt during 1960-2005
Depth of the Earthquakes in Sumatra-Andaman seismic belt during 1960-2005
Rupture, surfacewave propagationand co-seismicdisplacements measured by GPS of the great Sumatra earthquake on 26 December 2005
Aftershock Distribution of the great Sumatra earthquake on 26 December 2005
Magnitude of the Earthquakes in Sumatra-Andaman Seismic Belt on 26 December 2004
Depth of the Earthquakes in Sumatra-Andaman Seismic Belt on 26 December 2004
Major and Great Earthquakes in Sumatra-Andaman Seismic Belt during 1960-2005
Major Earthquakes in Sumatra-Andaman Seismic Belt during 1900-1959
Major Earthquakes in Sumatra-Andaman Seismic Belt during 1900-2005
Conclusions According to the study more than 3000 of the earthquakes of magnitude 5 in the Sumatra-Andaman seismic belt during 1960-2005 were analyzed and mapped.
About 10% decline of seismicity was found in 1990’s. Then the most destructive event of the region occurred on 26 December 2004 with consequently high seismicity. The drop of number of seismicity is precursory potential for earthquake prediction.
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