今週のセミナーについてお知らせいたします。

Here is information of the Unagi-seminar(10/25) this week.

**************♦ うなぎセミナーのご案内 (Unagi-seminar) ♦**************

日時：10月25日（木）14:00～16:00
場所：宇治キャンパス本館E棟2階E-232D
　　　（地震予知研究センター本館セミナー室）

Date and time: 25th Oct., 14:00 ~ 16:00
Room: E-232D @ Main building
Map: http://www.uji.kyoto-u.ac.jp/campus/map.html

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[発表者 (Presenter)]
坂上啓 (Hiromu SAKAUE)

[題目 (Title)]
1997-2010年に東海地方で発生したスロースリップイベント(SSE)の時空間発展の推定
Spatiotemporal evolution of slow slip event in the Tokai region, central Japan, during 1997-2010

[要旨 (Abstract)]
東海地方では、2000～2005年と2013～2016年に長期的スロースリップイベント（SSE）がGNSSデータを用いて観測されている（例えば，Ozawa et al., 2002; Miyazaki et al., 2006; Ozawa et al., 2016）。
加えて、傾斜計や歪み計といった測地観測から継続期間が数日～2週間程度の短期的SSEも数か月間隔で繰り返し発生していることが知られている。
本研究ではこれらの先行研究で用いられていなかった解析手法（Fukuda et al., 2008）を適用し、先行研究で行われていなかった長期的SSEと短期的SSEの時空間発展の同時推定を試みた。
本発表では、1997-2010年に発生した長期的SSEと短期的SSEの暫定的な結果を紹介し、簡単な考察を発表する。

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[発表者 (Presenter)]
Qwana Calvin

[題目 (Title)]
Doublet earthquake triggering for the April 2014 events in the Solomon Islands

[要旨 (Abstract)]
The Solomon Islands subduction zone is known for doublet earthquakes, which commonly occur as pairs with small separations in time and space (Lay and Kanamori, 1980; Schwartz et al., 1989; Xu and Schwartz, 1993). To understand the triggering process and established explanations for such behavior in this region, we investigated source process of doublet events that occurred in 2014 at 20:14 (UTC) on April 12th and 12:36 on April 13th, with moment magnitudes of 7.6 and 7.4, respectively near Makira Island (San Cristobal). The depths of the events were 23km and 39 km, respectively (GCMT). To evaluate the doublet source process of the events and recover the slip distribution on each of the faults, we use an iterative inversion method by Kikuchi and Kanamori (1991) for the teleseismic P waveforms, recorded from more than 20 stations of the Global Seismographic Network in a distance range of 30° to 90°. A fault plane with fixed strike and dip is placed in the region of the earthquake hypocenter and divided into subfaults, and a constant rupture velocity of 3 km/s is assumed. Synthetic waveforms are calculated at the teleseismic stations for dislocations at each subfault. Using the synthetic Green’s functions, the observed seismograms are inverted to determine the fault plane and obtain the distribution of slips for the two events. The result shows that the mechanism for the Mw7.6 main event shows more pure left-lateral strike-slip faulting with nodal plane of strike 116, dip 74 , and rake 24 as the NW-SE oriented nodal plane is almost parallel to Australian and Pacific Plates boundary. While result for the mechanism of the Mw7.4 event indicates thrust faulting on fault plane oriented WNW – ESE with two possible nodal plane of NP1 with strike 279, Dip 46, Rake 86 and NP2 with srike 104, Dip 44 and Rake 94. The possibility for the triggering of the second event was examined in terms of Coulomb failure stress changes. The components of strain tensor were calculated by using the subroutine DC3D (Okada, 1992). Using Hooke’s law that leads to the stress tensor, we calculated the changes in normal and shear stress and obtained Coulomb failure stress changes of +251.17 kPa and +31.41 kPa at the hypocenter for NP1 and NP2, respectively, in which both cases shows potential to encourage the probability likelihood of triggering the recipient fault. Our model shows that the Coulomb failure function with respect to the (NW-SE) nodal plane is the more probable triggering mechanism candidates responsible for the triggered event.

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皆さまのご来聴をお待ちしております。

=== 今後の予定(Schedule) ===
11/1 津田(Tsuda), 植村(Uemura)
11/8 片上(Katakami), 水戸川(Mitogawa)
11/15 三宅(Miyake)