Elucidation of activity for shallow low-frequency tremor in Nankai Trough

• Project/Area Number: 15K17745
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Solid earth and planetary physics
• Research Institution: Kyoto University
• Principal Investigator: Yamashita Yusuke 京都大学, 防災研究所, 助教 (80725052)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Project Status: Completed (Fiscal Year 2017)
• Budget Amount: ¥2,990,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥690,000); Fiscal Year 2016: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000); Fiscal Year 2015: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
• Keywords: 浅部低周波微動 / 日向灘 / スロー地震 / 海底地震観測 / プレート境界浅部

Outline of Final Research Achievements

In order to clarify the characteristics of shallow low-frequency tremor activity occurring along the Nankai Trough, we developed a method to detect events occurring near the trench axis from the land seismic station and estimate the source location. We developed new event detection method for the continuous seismic data although the accuracy of location was not improved beyond the conventional method. This method is continuously judging for the following parameter value: (1) ratio of the envelope amplitude of the low-frequency and high-frequency component, (2) ratio of each envelope amplitude and noise level. This method can be processed in quasi real time. To evaluate the performance, we applied to ocean bottom and land seismic observation data that including shallow tremor activity. As a result, the temporal change of shallow low frequency tremor activity along the Hyuga-nada to Nansei-shoto trench was obtained.

Research Products

• [Journal Article] Tidal Response in Shallow Tectonic Tremors (2017)
  • Author(s): Katakami S.、Yamashita Y.、Yakihara H.、Shimizu H.、Ito Y.、Ohta K.
  • Journal Title: Geophysical Research Letters Volume: 44 Issue: 19 Pages: 9699-9706
  • DOI: 10.1002/2017gl074060
  • Peer Reviewed / Open Access
• [Journal Article] Migrating tremor off southern Kyushu as evidence for slow slip of a shallow subduction interface (2015)
  • Author(s): Y. Yamashita, H. Yakiwara, Y. Asano, H. Shimizu, K. Uchida, S. Hirao, K. Umakoshi, H. Miyamachi, M. Nakamoto, M. Fukui, M. Kamizono, H. Kanehara, T. Yamada, M. Shinohara, and K. Obara
  • Journal Title: Science Volume: 348 Issue: 6235 Pages: 676-679
  • DOI: 10.1126/science.aaa4242
  • Peer Reviewed
• [Presentation] Tidal response in shallow micro low-frequency tremors (2017)
  • Author(s): 片上 智史・山下 裕亮・八木原 寛・清水 洋・伊藤 喜宏・太田 和晃
  • Organizer: JpGU-AGU Joint Meeting 2017
• [Presentation] Low-frequency tremor activity in the shallow part of Nankai trough and Ryukyu trench revealed by long-term ocean bottom observation (2017)
  • Author(s): Yusuke Yamashita, Masanao Shinohara, Hiroshi Yakiwara, Tomoaki Yamada, Kazuo Nakahigashi, Hajime Shiobara, Kimihiro Mochizuki, Takuto Maeda, and Kazushige Obara
  • Organizer: IAG-IASPEI 2017
  • Int'l Joint Research
• [Presentation] 長期海底地震観測に基づく日向灘～南西諸島海溝中部域にかけての浅部低周波微動活動の特徴 (2017)
  • Author(s): 山下裕亮・篠原雅尚・八木原寛・山田知朗・渡邉早姫・中東和夫・塩原肇・望月公廣・前田拓人・小原一成
  • Organizer: 2017年日本地震学会秋季大会
• [Presentation] Shallow slow earthquake activity from the Hyuga-nada to Ryukyu Trench (2017)
  • Author(s): Yusuke Yamashita, Masanao Shinohara, Hiroshi Yakiwara, Tomoaki Yamada, Saki Watanabe, Kazuo Nakahigashi, Hajime Shiobara, Kimihiro Mochizuki, Takuto Maeda, and Kazushige Obara
  • Organizer: AGU Fall Meeting 2017
  • Int'l Joint Research
• [Presentation] 緊急合同余震観測データを用いた高精度震源決定結果から推定される2016年熊本地震震源域の断層構造（序報） (2016)
  • Author(s): 山下裕亮・松本聡・中元真美・松島健・宮崎真大・清水洋・飯尾能久・2016年熊本地震合同地震観測グループ
  • Organizer: 日本地球惑星科学連合2016年大会
  • Place of Presentation: 幕張メッセ
  • Year and Date: 2016-05-24
• [Presentation] Long-term ocean bottom monitoring of slow earthquakes on the shallow plate interface in the Hyuga-nada region (3) (2016)
  • Author(s): 山下裕亮・篠原雅尚・山田知朗・中東和夫・塩原肇・望月公廣・前田拓人・小原一成
  • Organizer: 日本地球惑星科学連合2016年大会
  • Place of Presentation: 幕張メッセ
• [Presentation] 豊後水道周辺域におけるスロー地震の相互作用 (2016)
  • Author(s): 小原一成・高木涼太・山下裕亮・浅野陽一・松澤孝紀・田中佐千子・廣瀬仁・前田拓人
  • Organizer: 日本地球惑星科学連合2016年大会
  • Place of Presentation: 幕張メッセ
  • Invited
• [Presentation] Estimated the apparent released energy of shallow low-frequency tremor occurred Southeastern Kyusyu through frequency scanning at a single station (2016)
  • Author(s): 片上智史・山下裕亮・八木原 寛・清水洋・伊藤喜宏・太田和晃
  • Organizer: 日本地球惑星科学連合2016年大会
  • Place of Presentation: 幕張メッセ
• [Presentation] LONG-TERM OCEAN BOTTOM MONITORING OF SLOW EARTHQUAKES ON THE SHALLOW PLATE INTERFACE IN HYUGA-NADA, WESTERN PART OF THE NANKAI TROUGH (2016)
  • Author(s): Yusuke Yamashita, Masanao Shinohara, Tomoaki Yamada, Kazuo Nakahigashi , Hajime Shiobara, Kimihiro Mochizuki, Takuto Maeda, Kazushige Obara
  • Organizer: 9th Biennial Workshop on Japan-Kamchatka-Alaska Subduction Processes
  • Place of Presentation: University of Alaska, Fairbanks
  • Int'l Joint Research
• [Presentation] 南西諸島北部の海溝軸付近で発生する浅部低周波微動について (2016)
  • Author(s): 山下裕亮・八木原寛・平野舟一郎・小林励司・宮町宏樹・中尾茂・後藤和彦・馬越孝道・内田和也・松島健・清水洋・中東和夫・山田知朗・篠原雅尚
  • Organizer: 日本地震学会2016年度秋季大会
  • Place of Presentation: 名古屋国際会議場
• [Presentation] Long-term Ocean Bottom Monitoring for Shallow Slow Earthquakes in the Hyuga-nada, Nankai Subduction Zone (2015)
  • Author(s): Y. Yamashita, M. Shinohara, Y. Yamada, K. Nakahigashi, H. Shiobara, K. Mochizuki, T. Maeda, K. Obara
  • Organizer: 2015 AGU fall meeting
  • Place of Presentation: Moscone South, San Francisco, USA
  • Year and Date: 2015-12-18
  • Int'l Joint Research
• [Presentation] 日向灘における海底地震計・圧力計を用いたプレート境界浅部スロー地震の長期モニタリング (2) (2015)
  • Author(s): 山下裕亮・篠原雅尚・山田知朗・中東和夫・塩原肇・望月公廣・前田拓人・小原一成
  • Organizer: 日本地震学会2015年度秋季大会
  • Place of Presentation: 神戸国際会議場, 神戸市
  • Year and Date: 2015-10-26
• [Presentation] Long-term ocean bottom monitoring for shallow slow earthquakes in the Hyuga-nada, western part of the Nankai Trough (2015)
  • Author(s): Y. Yamashita, M. Shinohara, Y. Yamada, K. Nakahigashi, H. Shiobara, K. Mochizuki, T. Maeda, K. Obara
  • Organizer: 26th IUGG 2015 General Assembly
  • Place of Presentation: Prague congress center, Prague, Czech Republic
  • Year and Date: 2015-06-30
  • Int'l Joint Research
• [Presentation] 日向灘における海底地震計・圧力計を用いたプレート境界浅部スロー地震の長期モニタリング (2015)
  • Author(s): 山下裕亮・篠原雅尚・山田知朗・中東和夫・塩原肇・望月公廣・前田拓人・小原一成
  • Organizer: 日本地球惑星科学連合2015年大会
  • Place of Presentation: 幕張メッセ, 千葉市
  • Year and Date: 2015-05-27