1. Jesse Hsia, DU. 2. Emmy Chang, NTU. 3. Ms. SPOT 4. Mr. Jian, NTU.

Printed in August 28th, 2009

Application of Ocean Bottom Seismometer in Studying Marine Seismicity

Institute of Oceanography, National Taiwan University

aiwan is an island that located on the

boundary between Philippine Plate and Eurasian

Plate, and because of its active plate tectonic movements, it

raises Taiwan to one of the tallest islands on the Planet Earth.

Taiwan also sets on the Pacific Ring of Fire, therefore seismic

events are occurring as matter of course. According to the seismic

records, which I have observed from July of 2008 to September of

2008 from Taiwan Central Weather Bureau (CWB), I have noticed that

about 90% of those 4033 seismic events were formed in the ocean off

eastern Taiwan. Also I have noticed that the events from CWB can

only be recorded a minimum amount due to the lack of seismological

station distribution. It is obvious that the records from CWB were

limited when the events were farther than Longitude of 122°E. That

lack of seismic information were taken place in Ryukyu Arc and it

is one of the most seismic active spot due to its geological

formation as back-arc basin, which is submarine basins associated

with island arc and subduction zone. Therefore it is important for

us to know those specific seismic events that occurred in Ryukyu

Arc. I have picked seismic events from July of 2008 to September of

2008 from Ocean-Bottom Seismometer of RATS (Ryukyu Arc Tectonic &

Seismology) Report. As my result, the seismic events in Ryukyu Arc

are still very active, therefore it is important for us to do a

farther study in those areas. As above results, they indicate that

Taiwan has a lack of seismic study in the ocean. It is important to

develop Ocean-Bottom Seismometer (OBS) and Marine Cable Hosted

Observatory (MACHO), therefore geophysicists can have good

qualities of seismic data to calculate the energy released by

seismic events and be able to pre-

dict large seismic events for the

sake of citizens of Taiwan.

Abstract

Top Left: Final check before dropping OBS into 5,000 ft. of Ocean Deep.

Top Right: Collecting our OBS back, which indicated this trip was a success.

Bottom: The scientific ship Ocean Researcher II for a cruise from July

29 to July 31, 2009 at Okinawa Through.

According to this Map, about 90% of seismic events were formed in the Ocean. However CWB’s seismological

station cannot fully record all of seismic events due to the lack of Seismological Network in the ocean.

Moreover, CWB’s data were extremely imitated when events were farther than Longitude of 122°E. The Map

also let us know that seismic events were very active along 122°E to 122.5°E and 24°N to 24.5°N from

RATS’ data.

▲ OBS Station Fnet Station Rats Seismic Data CWB Seismic Data

(2007, Oct. 30 ). In About MACHO. Retrieved Aug. 26, 2009, from http://macho.ncu.edu.tw/aboutMACHO.html

(2009, Aug. 4 ). In WHOI: Instruments: Ocean-Bottom Seismometer. Retrieved Aug. 26, 2008, from http://viewInstrument.do?id=10347

Nakamura, M, and H. Katao. (2003). Microearthquakes and Faulting in the Southern Okinawa Trough. Tectonophysics, 372 (3-4), pp. 167-177.

References