更新日：2018.04.07
Updated: 2018.04.07
今週のセミナーについて連絡いたします。
**************♦ うなぎセミナーのご案内 (Unagi-seminar) ♦**************
日時： 5月31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: 31st May, 14:00 ~ 16:00
Room: E-232D @ Main building
Map: http://www.uji.kyoto-u.ac.jp/campus/map.html
====
[発表者 (Presenter)]
Calvin Qwana
[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 large earthquakes, commonly occur as pairs with small separations in time and space (Lay and Kanamori, 1980; Schwartz et al., 1989; Xu and
Schwartz, 1993). Understanding the triggering process in this region, would provide new explanations for the mechanisms of the doublet occurrence and provide useful information for
evaluating the seismic hazards for the region. The two events of earthquakes that occurred spontaneously in 2014 at 20:14 (UTC) on April 12th and 12:36 on April 13th, with magnitudes of
Mw7.6 and Mw 7.4 on Makira Island (San Cristobal) considered for purpose of this study. The depth of the first event was 23 km and the followed event was 39 km respectively. These sequence
offers comprehensive prospect to study the role of stress transfer and source mechanisms involved for doublet earthquake triggering in the region that known for occurrence of large size earthquake doublets (Mw?7). This piece present the preliminary results of a body-wave analysis of the two doublets events in the region in an attempt to provide a better understanding of the mechanics of seismic triggering, the state of the stress on the fault plane, and nature of the subjection between the Australia and the Pacific plates. To evaluate the doublet source process of the events and recover the distribution of slip on each of the faults, the iterative inversion method by Kikuchi and Kanamori (1991) employed for the teleseismic P waveforms recorded from 12 stations of the Global Seismographic Network in a distance range of 30° to 90°. For the inversion procedure, a fault plane with fixed strike and dip is placed in the region of the earthquake hypocenter and divided into subfaults, and a constant the rupture velocity is assumed., Synthetic waveforms are calculated at the teleseismic stations for dislocations at each subfault. Using these synthetic Green functions, the observed seismograms are inverted to determine the fault plane and obtain the distribution of slips for the two events. The relative locations, fault sizes, slip distributions and static stresses for the two events will be used to understand the rupture process and explore scenarios which favor the triggering process in the region. The Okada [1985] method then used to calculates analytical solution for internal deformation model due to shear and tensile faults in an elastic half-space. The model then used to simulate ground deformation produced by local perturbation. Assuming a rectangular fault geometry (length, width, depth, strike, dip) and 3-component dislocation amplitude (rake, slip and open), it then computes the displacements, tilts and strains at the free-surface.
====
[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
Spatio-temporal evolution of long-term and short-term slow slip events in the Tokai region, central Japan estimated from a very dense GNSS network, during 1997-2010
[要旨 (Abstract)]
1990年代初めごろからGNSSを用いた地殻変動の連続観測が行われ，これまで世界各地の海洋プレート沈み込み帯でスロースリップイベント(SSE)が数多く観測されている．SSEは非地震性の非常にゆっくりとした断層すべり現象で，日本列島では豊後水道，房総半島，東海地方などで繰り返し観測されており，Mw 7.0-7.5に相当するモーメントを数週間から数年間継続するすべりで解放する．これらのSSEは単にSSE，または長期的SSEと呼ばれる一方，西南日本では継続時間が数日から十日程度の短期的SSEも繰り返し観測されている．西南日本で発生する短期的SSEは低周波微動や低周波地震を伴うことが多く，Mw 5.5-6.0に相当するモーメントを解放する．
本研究の対象地域である東海地方は，南海トラフ巨大地震の破壊域の東端に位置し，フィリピン海プレートが駿河・南海トラフから西北西方向に年間2-6 cmの速度で，アムールプレートの下に沈み込んでいる．本発表では先行研究で既に報告されている2001年から2005年にかけて発生した長期的SSEの前後の期間を含めてGNSSデータを用いて解析を行い，長期的SSEの時空間発展とすべり欠損量の推定を行った．また暫定的な結果ではあるが，先行研究では用いられてこなかった解析手法を用いたことで推定できた短期的SSEの時空間発展についてもいくつか紹介する．
**************♦ 皆さまのご来聴をお待ちしています ♦**************
-------------------今後の予定（Schedule）----------------------
6/7 （教員枠）
6/14 植村、片上
6/21 加藤、山村
6/28 三宅、安富
7/5 水戸川、津田
7/12 M1×2
7/19 M1×2
今週のセミナーについて連絡いたします。
**************♦ うなぎセミナーのご案内 (Unagi-seminar) ♦**************
日時： 5月31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: 31st May, 14:00 ~ 16:00
Room: E-232D @ Main building
Map: http://www.uji.kyoto-u.ac.jp/campus/map.html
====
[発表者 (Presenter)]
Calvin Qwana
[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 large earthquakes, commonly occur as pairs with small separations in time and space (Lay and Kanamori, 1980; Schwartz et al., 1989; Xu and
Schwartz, 1993). Understanding the triggering process in this region, would provide new explanations for the mechanisms of the doublet occurrence and provide useful information for
evaluating the seismic hazards for the region. The two events of earthquakes that occurred spontaneously in 2014 at 20:14 (UTC) on April 12th and 12:36 on April 13th, with magnitudes of
Mw7.6 and Mw 7.4 on Makira Island (San Cristobal) considered for purpose of this study. The depth of the first event was 23 km and the followed event was 39 km respectively. These sequence
offers comprehensive prospect to study the role of stress transfer and source mechanisms involved for doublet earthquake triggering in the region that known for occurrence of large size earthquake doublets (Mw?7). This piece present the preliminary results of a body-wave analysis of the two doublets events in the region in an attempt to provide a better understanding of the mechanics of seismic triggering, the state of the stress on the fault plane, and nature of the subjection between the Australia and the Pacific plates. To evaluate the doublet source process of the events and recover the distribution of slip on each of the faults, the iterative inversion method by Kikuchi and Kanamori (1991) employed for the teleseismic P waveforms recorded from 12 stations of the Global Seismographic Network in a distance range of 30° to 90°. For the inversion procedure, a fault plane with fixed strike and dip is placed in the region of the earthquake hypocenter and divided into subfaults, and a constant the rupture velocity is assumed., Synthetic waveforms are calculated at the teleseismic stations for dislocations at each subfault. Using these synthetic Green functions, the observed seismograms are inverted to determine the fault plane and obtain the distribution of slips for the two events. The relative locations, fault sizes, slip distributions and static stresses for the two events will be used to understand the rupture process and explore scenarios which favor the triggering process in the region. The Okada [1985] method then used to calculates analytical solution for internal deformation model due to shear and tensile faults in an elastic half-space. The model then used to simulate ground deformation produced by local perturbation. Assuming a rectangular fault geometry (length, width, depth, strike, dip) and 3-component dislocation amplitude (rake, slip and open), it then computes the displacements, tilts and strains at the free-surface.
====
[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
Spatio-temporal evolution of long-term and short-term slow slip events in the Tokai region, central Japan estimated from a very dense GNSS network, during 1997-2010
[要旨 (Abstract)]
1990年代初めごろからGNSSを用いた地殻変動の連続観測が行われ，これまで世界各地の海洋プレート沈み込み帯でスロースリップイベント(SSE)が数多く観測されている．SSEは非地震性の非常にゆっくりとした断層すべり現象で，日本列島では豊後水道，房総半島，東海地方などで繰り返し観測されており，Mw 7.0-7.5に相当するモーメントを数週間から数年間継続するすべりで解放する．これらのSSEは単にSSE，または長期的SSEと呼ばれる一方，西南日本では継続時間が数日から十日程度の短期的SSEも繰り返し観測されている．西南日本で発生する短期的SSEは低周波微動や低周波地震を伴うことが多く，Mw 5.5-6.0に相当するモーメントを解放する．
本研究の対象地域である東海地方は，南海トラフ巨大地震の破壊域の東端に位置し，フィリピン海プレートが駿河・南海トラフから西北西方向に年間2-6 cmの速度で，アムールプレートの下に沈み込んでいる．本発表では先行研究で既に報告されている2001年から2005年にかけて発生した長期的SSEの前後の期間を含めてGNSSデータを用いて解析を行い，長期的SSEの時空間発展とすべり欠損量の推定を行った．また暫定的な結果ではあるが，先行研究では用いられてこなかった解析手法を用いたことで推定できた短期的SSEの時空間発展についてもいくつか紹介する．
**************♦ 皆さまのご来聴をお待ちしています ♦**************
-------------------今後の予定（Schedule）----------------------
6/7 （教員枠）
6/14 植村、片上
6/21 加藤、山村
6/28 三宅、安富
7/5 水戸川、津田
7/12 M1×2
7/19 M1×2
© Research Center for Earthquake Hazards.
© Research Center for Earthquake Hazards.
