第139回ジオダイナミクスセミナー
Geodynamics Seminar
"Deep structure of the Japan Island estimated from the Joint
inversion of local and teleseismic events"
講師：Mohamed Farouk（愛媛大学博士3年）
主催 ： 愛媛大学地球深部ダイナミクス研究センター
日時 ： ２００５年１１月１８日（金）17：00〜
場所 ： 愛媛大学理学部講義棟 ３０１教室
要 旨
The detailed 3-D P-wave velocity structures beneath the
Japan islands up to 700-km depth are estimated. 333 teleseismic
events recorded by the JARRAY and 7743 local and regional events
recorded by the Hi-net are used. A total of 260 thousand P-wave
travel time values are used. The P-wave arrival times of the
teleseismic data are picked using the multi-channel cross
correlation technique (VanDecar and Crosson, 1990). A scheme for
best events selection is applied. The Joint inversion technique
of Zhao et al. (1994) is used. The advantage of this technique is
its ability to resolve both the short and deep structures. Clear
images of low velocity zones beneath the active volcanoes in
Japan are shown. The Pacific slab is clearly imaged in all
sections having a thickness ranges from 80 to 150 km. The
Philippine Sea slab (PHS) is well imaged in the southern part of
Japan. It dips gently northward at shallow depth beneath Shikoku.
On the other side, it dips steeply westward reaching a depth of
500 km beneath Kyushu. Generally, its thickness is relatively
thinner (20-60km). The PHS shows a non-stable behavior of the
dipping angle in some parts specially the northward-dipping part.
This may indicate that the PHS has suffered dramatical changes in
its subductions rate. Finally, evidences of the deep dehydrations
and the upwelling convections are found.
問い合わせ先：土屋 卓久 TEL （089）927-8198
E-mail takut@sci.ehime-u.ac.jp
