DOI: 10.1126/science.1070378. Nonvolcanic Deep Tremor Associated with Subduction in Southwest Japan

Nonvolcanic Deep Tremor Associated with Subduction in Southwest Japan

10.1126/science.1070378

Crossref journal-article

American Association for the Advancement of Science (AAAS)

Science (221)

Abstract

Deep long-period tremors were recognized and located in a nonvolcanic region in southwest Japan. Epicenters of the tremors were distributed along the strike of the subducting Philippine Sea plate over a length of 600 kilometers. The depth of the tremors averaged about 30 kilometers, near the Mohorovic discontinuity. Each tremor lasted for at most a few weeks. The location of the tremors within the subduction zone indicates that the tremors may have been caused by fluid generated by dehydration processes from the slab.

Bibliography

Obara, K. (2002). Nonvolcanic Deep Tremor Associated with Subduction in Southwest Japan. Science, 296(5573), 1679â1681.

Authors 1

Kazushige Obara (first)

References 11 Referenced 1,139

10.1038/380309a0
10.1029/93JB03129
NIED Hi-net is a newly established seismic network (10). Each station consists of a three-component velocity seismometer with a natural frequency of 1 Hz installed at the bottom of a borehole with a depth of 100 to 200 m. The data are digitized at each station with a sampling frequency of 100 Hz and then the data packets attached with the absolute time information from a Global Positioning System clock are transmitted to the data center.
Vertical-component waveforms for a pair of stations are converted to envelopes with a frequency range of higher than 4 Hz and with a smoothing time of 10 s and they are resampled with a sampling interval of 1 s. A pair of envelope seismograms with a length of 2 min is used for calculation of the cross-correlation coefficient by moving a trace with the time lag of every 1 s to another fixed reference trace. The time lag which gives the maximum correlation coefficient should be the difference of the arrival time for a coherent seismic signal in the selected 2 min observed in the two stations. If the maximum correlation coefficient is less than 0.9 the time lag is not applied for the further process because there is no coherent signal. Such a correlation process is carried out for all pairs of stations in the target area. The measured time lags with a good correlation are averaged spatially to calculate the distribution of the relative arrival time like the net adjustment which is used in the geodetic survey. The cross-correlation analysis is carried out with the moving time window of 1 min; therefore we can calculate the location of tremors once every 1 min continuously.
A. Katsumata N. Kamaya Seismol. Soc. Jpn. Fall Meeting B16 (2001).
Ukawa M., Obara K., Bull. Volcanol. Soc. Jpn. 38, 187 (1993). / Bull. Volcanol. Soc. Jpn. by Ukawa M. (1993)
10.1016/0040-1951(94)90243-7
S. Ohmi Eos 82 (fall suppl.) 871 (2001).
10.1016/S0012-821X(98)00266-0
K. Obara et al. Eos 81 (fall suppl.) 863 (2000).
M. Nakamura et al. Ann. Disaster Prev. Res. Inst. Kyoto 40 B-1 1 (1997).

Dates

Type	When
Created	23 years ago (July 27, 2002, 5:54 a.m.)
Deposited	1 year, 7 months ago (Jan. 9, 2024, 11:01 p.m.)
Indexed	3 days, 5 hours ago (Aug. 21, 2025, 1:14 p.m.)
Issued	23 years, 2 months ago (May 31, 2002)
Published	23 years, 2 months ago (May 31, 2002)
Published Print	23 years, 2 months ago (May 31, 2002)

Funders 0

None

BibTeX

@article{Obara_2002, title={Nonvolcanic Deep Tremor Associated with Subduction in Southwest Japan}, volume={296}, ISSN={1095-9203}, url={http://dx.doi.org/10.1126/science.1070378}, DOI={10.1126/science.1070378}, number={5573}, journal={Science}, publisher={American Association for the Advancement of Science (AAAS)}, author={Obara, Kazushige}, year={2002}, month=may, pages={1679–1681} }

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