Report 3 (April 22, 2015): Emergency Survey Report

  2016 Kumamoto Earthquake Main Page

Updated on April 22, 2016

The contents of this website are English translation of the Japanese website of “Report 3: Emergency Survey by Y. Shirahama, H. Mori, T Maruyama, and M. Yoshimi“,

An emergency survey was conducted near the epicenter of the 2016 Kumamoto earthquake to survey surface deformations, starting on April 16 after the M7.3 earthquake (Figure 1). Surface ruptures are identified along the northern Hinagu fault zone (Takano-Shirahata segment), and Futagawa segment and a part of Uto segment of the Futagawa fault zone (Figure 1). Surface deformation suggesting an earthquake fault is also observed in Uto area of the Futagawa fault zone. Photos of some earthquake faults and surface deformation are shown below (Photos 1 to 16).

Valuable and helpful information about the location of the earthquake faults on the ground was provided by Dr. Takashi Nakata, Emeritus Professor at Hiroshima University, Professor Hiroyuki Goto, Kyoto University, and Dr. Masashi Omata of Pasco Corporation.

 

location

Figure 1. Distribution of surface rupture and deformations identified in the current survey. The base map is the Active Fault Map in Urban Area (Ikeda et al., 2001) by the Geospatial Information Authority of Japan (modified from GSJ, 2016).

 

Photos of identified surface earthquake faults

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Photo 1. Northeastward view of right lateral displacement producing mole-track structure in a field at Douzon, Mashiki Town. The fault line extends into a hill in the back of the photo, passing by a blue vinyl greenhouse. White arrows indicate the location of the fault line and red arrows show the sense of displacement (April 16, 2016; taken from GSJ, 2016).

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Photo 2. Right lateral displacement in a field of Douzon, Mashiki Town (northwestward view). Right lateral offset of the footpath in the field is about 200 cm (April 16, 2016; taken from GSJ, 2016)

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Photo 3. Shortening deformation on the paved road in Kamijin, Mashiki Town (southeastward view). The fault runs N70E with vertical displacement of about 40 cm (April 16, 2016; taken from GSJ, 2016).

 

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Photo 4. Right lateral displacement with mole-track structure in the west of Shimojin, Mashiki Town (northeastward view). Lateral displacement is about 100 cm and vertical displacement is about 20 cm (April 16, 2016; taken from GSJ, 2016).

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Photo 5. Vertical displacement of about 35 cm is observed to continue to the crossing in the back of the photo, in a field of Mitake, Mashiki Town (northeastward view; April 16, 2016; taken from GSJ, 2016).

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Photo 6. The flexural deformation in a drained paddy field with N70W left lateral component, west of Shimojin, Mashiki Town (west-northwestward view). Vertical displacement is about 15-20 cm and left lateral displacement is about 20 cm (April 16, 2016; taken from GSJ, 2016).

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Photo 7. Right lateral displacement in a drained paddy field, southwest of Mitake, Mashiki Town (northeastward view). The fault can be traced to the place shown in Photo 5, through a deformed guardrail, crossing the road and passing the right side of a house in the far back of the photo (April 16, 2016; taken from GSJ, 2016).

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Photo 8. Right lateral displacement of about 40-50 cm in a parking lot of a community center in Akai, Mashiki Town (northwestward view; April 16, 2016; taken from GSJ, 2016).

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Photo 9. Northeastward view of right lateral displacement in a drained paddy field and mole-track structure, west of Togawa, Mashiki Town. (April 16, 2016; taken from GSJ, 2016).

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Photo 10. Right lateral displacement of about 50 cm in a drained paddy field, west of Togawa, Mashiki Town (south-southeastward view; April 16, 2016; taken from GSJ, 2016).

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Photo 11. Vertical displacement of about 15 cm, cutting the national route 443 at the south of the Iino Elementary School (west-southwestward view; April 16, 2016; taken from GSJ, 2016).

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Photo 12 Right lateral displacement on the road pavement, west of Tsuchiyama, Mashiki Town (westward view; April 16, 2016; taken from GSJ, 2016).

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Photo 13. Right lateral displacement of about 50 cm in a drained paddy field at Takaki, Mifune Town (southward view; April 17, 2016; taken from GSJ, 2016).

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Photo 14. Right lateral displacement shown by the offset of gutter in the southern border road of Kamitakano, Mifune Town (eastward view). The right lateral displacement indicated by the offset of the gutter is about 50 cm (April 17, 2016; taken from GSJ, 2016).

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Photo 15. Open cracks with vertical offset of the road pavement along the southern border of Kushijima, Mashiki Town (east-northeastward view). The vertical offset of the road surface is about 10 cm. The sporadic distribution of open cracks from northeast to southwest in the paddy field is shown by white arrows (April 16, 2016; taken from GSJ, 2016).

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Photo 16. Open cracks along the boundary between topographic high and drained paddy field, south of Kushijima, Mashiki Town. The open cracks were created on the ramp of south-side-up flexure. The fence beyond the person was deformed by the flexure (west-southwestward view). The vertical displacement of the ground along the flexure is about 20 cm or more. The south-side-up flexure and open cracks continuously distributed along the topographic boundary. Curved white arrow shows flexure ramp shape (April 17, 2016; taken from GSJ, 2016).

Reference:

Yasutaka Ikeda, Noboru Chida, Takashi Nakata, Heitaro Kaneda, Masayoshi Tajikara, Shinji Takazawa (2001) Active Faults in Urban Area Map [Kumamoto], GSI Tech. Rep. D.1-No.368.

2016 Kumamoto Earthquake Main Page

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2016 Kumamoto Earthquake Report 2 (April 17, 2016): Seismic activities and related information in central Kyushu since April 15, 2016

2016 Kumamoto Earthquake Main Page

Last updated on April 21, 2016

The contents of this website are English translation of the Japanese website of “2016 Kumamoto Earthquakes and related information“, the Geological Survey of Japan (GSJ), AIST.

Seismic activities has been increasing in Kumamoto Prefecture and Oita Prefecture, and landslides occurred in many places of the Minami-Aso Village, near the Aso volcano.

Seismic activity and geological information in central Kyushu

Fig.1

Orange circles denote epicenters of two major earthquakes: M6.5 earthquake at 21:26 JST on April 14 and M7.3 earthquake at 01:25 JST on April 16 determined by Hi-net of the National Research Institute for Earth Science and Disaster Prevention (NIED). Blue circles are aftershocks and other smaller earthquakes from 00:00 JST, April 14 to 07:00 JST, April 16, which were also determined by Hi-net (NIED). Size of the circles is proportional to the magnitude of the earthquakes. Red lines show traces of active faults in this area. Base map is 1:200,000 Seamless Geological Map of Japan (GSJ, AIST). (modified from GSJ, 2016)

Epicenters of the present earthquake sequence show extremely wide distribution in the zone of Beppu-Shimabara Graben from the west to the east coast of the middle Kyushu with a distance of about 200 km and a width of a few tens of km. The earthquake sequence are presently very active at Hinagu Fault Zone and Futagawa Fault Zone in western Kyushu, Aso Volcano area in central Kyushu, and Beppu-Haneyama Fault Zone in eastern Kyushu.

 

Distribution of epicenters plotted on 1:200,000 geological maps in Kumamoto Prefecture

The Hinagu Fault Zone and Futagawa Fault Zone, which were the sources of the M6.5 earthquake on April 14 and the M7.3 earthquake on April 16 respectively, are located between a hilly area of Cretaceous accretionary complex and Jurassic metamorphic formations in the south, and a flatter area of Kumamoto Plain and Yatsushiro Plain in the north. The M6.5 earthquake at 21:26 JST on April 14 was on Hinagu Fault Zone and the M7.3 earthquake at 01:25 JST on April 16 was on Futagawa Fault Zone.

Fig2-1

Distribution of epicenters around the two major earthquakes in Kumamoto plotted on 1:200,000 geological mapsCircles indicate epicenters of earthquakes determined by Hi-net (NIED). Orange circles are the two major earthquakes. Size of the circles is proportional to the magnitude of the earthquakes (modified from GSJ, 2016).

Fig2-2

1:200,000 geological maps of “Kumamoto (Hoshizumi et al.,2004)” and “Yatsushiro and a part of Nomozaki (Saito et al., 2010)” by GSJ, AIST (modified from GSJ, 2016).

 

Distribution of epicenters plotted on 1:200,000 geological maps around Aso Caldera.

Seismic activity has increased around Aso Caldera, Kumamoto Prefecture, after the M7.3 earthquake at 01:25 JST on April 16. The epicenters are located in the northern half of Aso Caldera and aligned along a NE-SW direction.

Fig. 3

Blue circles are earthquakes from 00:00 JST, April 14 to 12:00 JST, April 16, determined by Hi-net (NIED). Size of the circles is proportional to the magnitude of the earthquakes (modified from GSJ, 2016).

 

Distribution of epicenters plotted on 1:200,000 geological maps in Beppu area

Seismic activity has also increased in Beppu City and Yufu City, Oita Prefecture, after the M7.3 earthquake at 01:25 JST on April 16. The epicenters are located along Beppu-Haneyama Fault Zone and are aligned along a ENE-WSW direction.

Fig.4

Blue circles are earthquakes from 00:00 JST, April 14 to 12:00 JST, April 16, determined by Hi-net (NIED). Size of the circles is proportional to the magnitude of the earthquakes (modified from GSJ, 2016).

 

Landslides in Minami-Aso Village in Aso Caldera

Many landslides occurred in the Minami-Aso Village, located within the Aso Caldera, after the M7.3 earthquake on April 16. Among them, large one on the slope above the west of Aso-Ohashi Bridge on Kurokawa River broke the bridge completely. This area is located in the western caldera wall of Aso Caldera and underlain by pre-Aso Caldera lava and pyroclastic rocks erupted 80k to 40k years ago. The caldera wall is steep and can collapse by a strong earthquake motion. Other landslides, including those at the Jigoku Hot Spring, occurred on steep hills of post-caldera lava flow deposits inside the caldera.

Fig. 5

(Taken from GSJ, 2016)

Fig6

(Taken from GSJ, 2016)

 

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2016 Kumamoto Earthquake Report 1 (April 15, 2016): Aftershock distribution and geology in this area

2016 Kumamoto Earthquake Main Page

Last updated on April 21, 2016

The contents of this website are English translation of the Japanese website of “2016 Kumamoto Earthquakes and related information“, the Geological Survey of Japan (GSJ), AIST.

aftershocks1

An orange circle denotes the epicenter of the main shock determined by Hi-net (NIED) and blue circles stand for after shocks (until 9:00 on April 15). Red lines show traces of active faults in this area. Base map is 1:200,000 Seamless Geological Map of Japan (GSJ, AIST). (modified from GSJ, 2016)

Figures below show after shock distribution and geology in this area.

aftershock2

Close-up of the figure above. Symbols are the same as above. Base geological map is 1:200,000 Kumamoto (Hoshizumi et al.,2004) and Yatsushiro and a part of Nomozaki (Saito et al., 2010) by GSJ, AIST (modified from GSJ, 2016).

 

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The M6.5 and M7.3 Kumamoto Earthquakes on April 14 and 16, 2016

Last updated on May 17, 2016

The contents of this website are English translation of the Japanese website of “2016 Kumamoto Earthquakes and related information“, the Geological Survey of Japan (GSJ), AIST.

A moderate earthquake of M6.5 occurred in Kumamoto Prefecture, Kyushu, southwestern Japan, at 21:26 JST on April 14, 2016. It was generated on a right-lateral strike-slip fault, northern part of the Hinagu fault zone. Depth of the epicenter was shallow (about 11 km in depth; JMA), and very strong ground motion was recorded near the source fault. A larger earthquake of M7.3 occurred at 1:25 JST on April 16, 2016 on the Futagawa fault zone, which is the northern neighbor of the Hinagu fault zone.

The Geological Survey of Japan (GSJ) set up the Emergency Survey Headquarters on April 15 to conduct systematic responses.

 

Influence of the Kumamoto Earthquake on groundwater resources

Fig2

Report 3 (April 22, 2015): Emergency Survey Report

location

 

Report 2 (April 17, 2016): Seismic activities and related information in central Kyushu since April 15, 2016

Fig.1-1-2

 

Report 1 (April 15, 2016): Aftershock distribution and geology in this area

aftershocks1

 

Related websites

 

Update information

  • May 17, 2016: Influence of the Kumamoto Earthquake on groundwater resources is released.
  • April 22, 2016: 2016 Kumamoto Earthquake Report 3 is released.
  • April 17, 2016: 2016 Kumamoto Earthquake Report 2 is released.
  • April 15, 2016: 2016 Kumamoto Earthquake Report 1 is released.

 

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インドネシア地質総局 (Geological Agency of Indonesia) 出張報告

日程: 2016年2月29日(月)〜3月3日(木)

訪問先: インドネシア地質総局(Geological Agency of Indonesia)

目的: CCOP地質情報総合共有(GSi)プロジェクト及びインドネシア火山情報システムに関する研究打ち合わせ

訪問者: 宝田晋治,Joel Bandibas

報告:

インドネシア地質総局(Geological Agency of Indonesia)と産総研地質調査総合センターは,2014年12月にMOUを締結しており,火山,地熱,地質情報分野で研究協力を進めている所である.今回の訪問では,一昨年のCCOP総会で東・東南アジア各国が合意し,2015年度から活動を開始したCCOP地質情報総合共有(Geoinformation Sharing Infrastructure, GSi)プロジェクト,及び約2年前から共同研究として開発を続けてきたインドネシア火山情報システムに関する研究打ち合わせを行った.

2月29日(月)には,インドネシア地質総局内のインドネシア火山地質防災センター(CVGHM)を訪問し,Supriyati Andreastuti氏を始めとする火山関係者約10名と,インドネシア火山情報システム(図1A, B)の公開について協議を行った.インドネシア火山情報システムは,CVGHMのOktory Prambada氏とJoel Bandibas,宝田の3名が中核となり作成したインドネシアの活火山情報(ハザードマップ,地質図,噴火履歴,災害履歴など)をWebGISで閲覧出来るようにしたシステムである.2年前から開発を続け,今回一般公開する事となった.公開用のサーバーについては,CCOP地質情報総合共有(GSi)プロジェクトにおいて,インドネシア地質総局に新たに導入したサーバーを使用することで合意した(図2).今後,暫定サーバー上の内容を順次新サーバーに移行し,来年度内の一般公開を目指す予定である.

インドネシア火山情報システム

図1A. インドネシア火山情報システム.

Merapi_HM

図1B. インドネシア火山情報システム上のメラピ火山のハザードマップ

20160229_114611

図2. CVGHMにおける検討会議の様子.

29日は,さらに2016年5月に出版予定の東アジア地域地震火山災害情報図について,内容を協議した.また,CVGHMに2016年に新たに導入された火山のモニタリングシステム(図3)や,JICA予算で新しくなった地質標本館(図4)の見学を行った.

2016-02-29 08.50.23

図3. CVGHMに新たに導入された火山モニタリングシステム.

2016-02-29 15.19.18

図4. 地質標本館館(写真は標本館館長)

3月1日(火)には,インドネシア地質総局の各部署のGeoinformation関係者と約15名とCCOP地質情報総合共有プロジェクトに関する会合を行った(図5).冒頭に,地質総局企画室代表のDikdik Pribadi氏から挨拶があり,その後,宝田からGSiプロジェクトの概要を説明した(図6).そして,Joko Parwata氏からインドネシア地質総局における地質情報整備の現状について説明があった.今回の訪問では,また,2016年9月にインドネシアで開催予定の第1回GSi国際ワークショップについて,検討を行い,第1回WSをジョグジャカルタにて,9月20-23日の4日間の日程で開催することで合意した.
午後には,Center for Geological Survey (CGS,図7),Center for Groundwater Resources and Environmental Geology (CGREG, 図8), Center for Geological Resources (CGR, 図9,10)を訪問し,各部署の取り組み等を見学するとともに,議論を行った.

CVGHM_meeting_pic

図5.インドネシア地質総局の各部署のGeoinformation関係者との会合の様子.

GSI_site

図6.新しく開発したGSiプロジェクト用のデータ登録システム.主題ごとのポータルサイトを構築可能.

GA_meeting_pic1

図7. Center for Geological Survey (CGS)の見学の様子.

GA_meeting_pic2

図8. Center for Groundwater Resources and Environmental Geology (CGREG)の観測井.

GA_meeting_pic3

図9. Center for Geological Resources (CGR)での議論の様子.

GA_meeting_pic4

図10. CGRの関係者.

3月2日(水)には,Joel Bandibas氏の講習によりGSiシステムへのデータ実装,モバイルシステムの構築に関する実習を行った(図11, 12).各部署より約25名が参加した.冒頭では,Center for Geological Survey代表から挨拶があった(図13).

GA_WS1

図11. CCOP地質情報総合共有システムの実習の様子.

GA_WS2

図12. GSiシステムの実習の様子.

GA_WS3

図13. Center for Geological Survey代表の挨拶

3月3日(木)には,バンドン南にあるGuntur火山観測所の見学(図14)を行い,Papandayan火山の地質巡検に参加した(図15).

Fieldtrip1

図14. Guntur火山観測所見学の様子.右から2人目はGuntur観測所所長.

Fieldtrip2

図15. Papandayan火山巡検の様子.左端は,Papandayan火山観測所所長.