Shear wave polarization anisotropy in and around the focal region of the 2005 West off Fukuoka Prefecture earthquake

Watanabe, Atsushi; Matsumoto, Satoshi; Matsushima, Takeshi; Uehira, Kenji; Matsuwo, Norimichi; Shimizu, Hiroshi

doi:10.1186/bf03352674

Cited by 3 publications

(2 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similar inferences have been made by e.g. Watanabe et al (2006). It is would therefore be unrealistic to expect a consistent pattern of u directions to be readily visible especially in such a complex zone.…”

Section: Resultsmentioning

confidence: 57%

Structurally controlled seismic anisotropy above small earthquakes in crustal rocks beneath the Rwenzori region, Albertine Rift, Uganda

Batte

Rümpker

Lindenfeld

et al. 2014

Journal of African Earth Sciences

View full text Add to dashboard Cite

Section: Resultsmentioning

confidence: 57%

Structurally controlled seismic anisotropy above small earthquakes in crustal rocks beneath the Rwenzori region, Albertine Rift, Uganda

Batte

Rümpker

Lindenfeld

et al. 2014

Journal of African Earth Sciences

View full text Add to dashboard Cite

“…The imaging of the scatterer distribution shows that higher strengths are distributed at the SE-extension of the fault plane of the mainshock, which corresponds to the region where the rupture process of the mainshock stopped. Watanabe et al (2006) studied the shear wave polarization anisotropy in and around the focal region. Most of the leading shear wave polarization directions were oriented in the nearly E-W direction, consistent with the maximum compressional stress inferred from the focal mechanism solutions, thus indicating that the observed anisotropy was caused by the stressinduced microcracks.…”

mentioning

confidence: 99%

Introduction to the special section for the 2005 West Off Fukuoka Prefecture Earthquake

Shimizu

2006

Earth Planet Sp

Self Cite

View full text Add to dashboard Cite

On 20 March 2005, the 2005 West Off Fukuoka Prefecture earthquake with Japan Meteorological Agency magnitude (M JMA ) of 7.0 occurred in the offshore region of Fukuoka Prefecture, in northern Kyushu, Japan. This earthquake caused more than 1,000 casualties and damaged many buildings in the surrounding area, especially on Genkai Island as well as in and around Fukuoka City.Because the 2005 West Off Fukuoka Prefecture earthquake was one of the largest intraplate earthquakes in recorder history occurring ages at the junction of the Southwestern Japan Arc and the Ryukyu Arc, intensive seismological and geodetic studies were carried out in its aftermath. Ten papers from these studies were published as the special section for the 2005 West Off Fukuoka Prefecture earthquake (1) of Earth, Planets and Space, Vol. 58, No.1, 2006. In addition, eight papers are published in the special section (2) of this issue. These studies have revealed important characteristics of the earthquake as summarized in the following paragraphs.The mainshock and aftershocks were mainly aligned NW-SE in an approximately 25 km long trend, and the hypocenters of the aftershock region were distributed on a nearly vertical plane at depths of 2-16 km. The mainshock was located near the central part of the aftershock region, with a depth of 9.5 km. These findings suggest that the strike and dip of the fault plane of the earthquake are approximately N60• W and 90• , respectively, and the length and width of the fault are about 25 km and 14 km, respectively. The largest aftershock of M JMA 5.8 occurred near the SE edge of the main aftershock region, and the aftershock region extended about 5 km in the SE direction based on the secondary aftershock activity, which had a different strike angle from that of most of the aftershocks. Following the most intense aftershock activity, there was no distinct enlargement of the aftershock region, and the aftershock activity gradually declined .The fault structure has been discussed in detail on the basis of precise analyses of aftershock distribution based on onshore and offshore seismic observations made with densely located ocean bottom seismometers . The fault plane is bent near both the NW and SE Copy right c The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences; TERRAPUB.edges: the strike of both edges differs from that of the central part, which includes the hypocenter of the mainshock by 15• in the clockwise direction. T. and Ito et al. (2006) determined moment tensor solutions of the mainshock and aftershocks, and both groups found spatial variation of the source mechanisms which corresponded to the fault bending. Uehira et al. (2006) showed that the main fault was divided into two segments bordering on the depth of the mainshock. There are 10• differences in both of strike and the dip angles between the lower and upper segments. The ge...

show abstract

Precise aftershock distribution of the 2005West Off Fukuoka Prefecture Earthquake (Mj=7.0) using a dense onshore and offshore seismic network

et al. 2006

Self Cite

View full text Add to dashboard Cite

The 2005 West Off Fukuoka Prefecture Earthquake (Mj=7.0) occurred on March 20, 2005 in the northern part of Kyushu, Japan. To study the aftershock activity, we deployed eleven pop-up type ocean bottom seismometers (OBSs), sixteen locally recorded temporary stations, and eight telemetered temporary stations in and around the epicenter region. We combined data from these stations and permanent stations located around the aftershock area, and determined the hypocenter of the mainshock and aftershocks. The mainshock was in the northwestern central part of the aftershock region, at a depth of 9.5 km. The mainshock was on a left-lateral strike-slip fault. Aftershocks were located in a depth range of 1-16 km and laterally extend for about 25 km in a NW-SE direction. We found that the aftershocks fell into four groups. This might be due to the heterogeneous structure in the source region. In the group that includes the mainshock, we estimated two fault planes bordering on the depth of the mainshock. There are 10-degree differences in both strike and dip angles between the lower and upper planes. From the aftershock distribution and the focal mechanisms, the rupture first propagated downward, and then propagated upward. Key words: The 2005 West Off Fukuoka Prefecture Earthquake, aftershock distribution, ocean bottom seismometer (OBS), temporary telemetered and locally recorded observations.

show abstract

Shear wave polarization anisotropy in and around the focal region of the 2005 West off Fukuoka Prefecture earthquake

Cited by 3 publications

References 16 publications

Structurally controlled seismic anisotropy above small earthquakes in crustal rocks beneath the Rwenzori region, Albertine Rift, Uganda

Structurally controlled seismic anisotropy above small earthquakes in crustal rocks beneath the Rwenzori region, Albertine Rift, Uganda

Introduction to the special section for the 2005 West Off Fukuoka Prefecture Earthquake

Precise aftershock distribution of the 2005West Off Fukuoka Prefecture Earthquake (Mj=7.0) using a dense onshore and offshore seismic network

Contact Info

Product

Resources

About