earth

1
Seismicity in Sumatra-Andaman Seismic Belt
during 1960-2005
Adisorn FoongkajornChiang Mai Seismic Station
2
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 1960s, 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 1990s. Then the most destructive event of the
region occurred on 26 December 2004 with
consequently high seismicity.
3
Scope of the study
4
SeismicPrecursors
http//elvis.engr.wisc.edu/UER/uer96/author3/fig2.
gif
5

• Seismic precursors- Decreasing Vp/Vs
  (10-20 change) Electrical resistivity (15
  change) Number of seismicity
• Increasing (geodetic measurements) Tilt
  Vertical motion Volumetric strain
• (Bath, 1979298)

6
First Episode of the Great Sumatra Earthquake
7
Indian Plate that has played an important roll in
the Sumatra-Andaman Seismic Belt
8
Panoramic Scene of the Sumatra-Andaman seismic
belt
9
Origin of Volcanic Island Arc as Andaman and
Nicobar were originated
10
Epicentral Distribution in Sumatra-Andaman
seismic belt during 1960-2005
11
Epicentral Distribution in Sumatra-Andaman
seismic belt during 1960-2005
12
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
Total 3152
Development of highly sensitive seismograph
13
Number of the Earthquakes in Sumatra-Andaman
Seismic Beltduring 1960-2005
14
Magnitude of the Earthquakes in Sumatra-Andaman
seismic beltduring 1960-2005
Magnitude Number
? 9 1
? 8 1
? 7 17
? 6 186
? 5 2947
Total 3152
15
Magnitude of the Earthquakes in Sumatra-Andaman
seismic beltduring 1960-2005
16
Depth Distribution of the Earthquakes in
Sumatra-Andaman seismic beltduring 1960-2005
17
Cumulative Depth Distribution of the Earthquakes
in Sumatra-Andaman seismic belt during 1960-2005
1960-1969
1960-1979
1960-1989
1960-1999
1960-2005
18
Cumulative Depth Distribution of the Earthquakes
in Sumatra-Andaman seismic belt during 1960-2005
19
Depth Contour of the Earthquakes in
Sumatra-Andaman seismic belt during 1960-2005
20
Depth of the Earthquakes in Sumatra-Andaman
seismic belt during 1960-2005
21
Rupture, surfacewave propagationand
co-seismicdisplacements measured by GPS of the
great Sumatra earthquake on 26 December 2005
22
Aftershock Distribution of the great Sumatra
earthquake on 26 December 2005
23
Magnitude of the Earthquakes in Sumatra-Andaman
Seismic Belt on 26 December 2004
24
Depth of the Earthquakes in Sumatra-Andaman
Seismic Belt on 26 December 2004
25
Major and Great Earthquakes in Sumatra-Andaman
Seismic Belt during 1960-2005
26
Major Earthquakes in Sumatra-Andaman Seismic Belt
during 1900-1959
27
Major Earthquakes in Sumatra-Andaman Seismic Belt
during 1900-2005
28
(No Transcript)
29
(No Transcript)
30
(No Transcript)
31
(No Transcript)
32
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 1990s. 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.
33
Thank you very much