2012 Chiba earthquake

The 2012 Chiba earthquake (千葉県東方沖地震, Chiba-ken Toho-oki Jishin, lit. "Offshore Eastern Chiba Earthquake") occurred along the northeastern coast of Chiba Prefecture, Japan at 21:05 JST (12:05 UTC) on Wednesday, 14 March. Although its epicentre lay just offshore near Chōshi city, the shallow magnitude 6.1 Mj earthquake produced considerable shaking inland through much of the Bōsō Peninsula and lower Ibaraki Prefecture. It occurred as a result of normal faulting in a seismically quiet region, possibly in response to the magnitude 9.0 Mw 2011 Tōhoku earthquake.[3]

Offshore Eastern Chiba earthquake
千葉県東方沖地震
Tokyo
UTC time2012-03-14 12:05:04
ISC eventn/a
USGS-ANSSComCat
Local date14 March 2012 [1]
Local time21:05 JST
Magnitude6.1 Mj
Depth10 km (6 mi)
Epicenter35.75°N 140.93°E / 35.75; 140.93
TypeInterplate
Areas affectedJapan
Max. intensityShindo 5+[2]
TsunamiNo
LandslidesNo
Casualties1 dead, 1 injured

Effects

Despite its considerable magnitude the earthquake caused only localised light to moderate structural damage in Chiba, owing in part to Japan's advanced earthquake engineering. The most significant effects occurred in Chōshi and Katori cities, where a few walls collapsed and several buildings sustained damage. In Funabashi city an elderly resident suffered a fatal heart attack during the quake, and a falling object caused one minor injury in Kisarazu city.[4][5]

Background

A seismically volatile country, Japan frequently experiences natural disasters such as earthquakes, volcanic eruptions and tsunamis.[6] The entire archipelago forms a part of the Pacific Ring of Fire, a massive belt of volcanoes and trenches.[7] The largest of the islands, Honshu is characterised by numerous inland fault systems and large subduction zones which are a result of the interaction between several tectonic plates.[8] At the junction of the continental Okhotsk Plate and the oceanic Philippine Sea and Pacific plates lies the populous Kantō Region, which has had a long history of devastating earthquakes.[9]

Situated on the Bōsō Peninsula in eastern Kantō, Chiba Prefecture is surrounded by a region of complex tectonic settings.[10] To the south the Philippine Sea Plate is subducted beneath Okhotsk Plate creating the offshore Sagami Trench; the Pacific Plate subducts the region from the east, forming the Japan Trench.[11] Despite this Chiba Prefecture has experienced relatively little effects from earthquakes.[12] Since 1923 most events have occurred well offshore, within the magnitude 5.0–6.0 Mj range, at somewhat shallow focal depths.[13] The most significant earthquake, known as the 1987 Chiba-ken Toho-oki earthquake, occurred on 17 December 1987.

See also

References
  1. Preliminary Earthquake Report: Magnitude 6.0 near the East Coast of Honshu, Japan (Report). United States Geological Survey. 14 March 2012. Retrieved 29 March 2012.
  2. Earthquake Information (Earthquake and Seismic Intensity Information) Issued at 21:09 JST 14 Mar 2012 (Report). Japan Meteorological Agency. 14 March 2012. Archived from the original on 16 April 2012. Retrieved 13 April 2012.
  3. 千葉県内１人死亡、１人負傷　１４日の千葉東方沖地震. Asahi Shimbun (in Japanese). 15 March 2012. Retrieved 29 March 2012.
  4. PAGER – M 5.7 – Near the East Coast of Honshu, Japan (Report). United States Geological Survey. 14 March 2012. Retrieved 29 March 2012.
  5. 千葉県東方沖を震源とする地震（確定報） (PDF) (Report) (in Japanese). Fire and Disaster Management Agency. 15 March 2012. Archived from the original (PDF) on 19 April 2012. Retrieved 29 March 2012.
  6. Fukagawa, M (July 2007). "Nephrology in Earthquakes: Sharing Experiences and Information". Clinical Journal of the American Society of Nephrology. American Society of Nephrology. 2 (4): 803–04. doi:10.2215/CJN.00530107. PMID 17699497.
  7. Asahiko Taira (2001). "Tectonic evolution of the Japanese island arc system" (PDF). Annual Review of Earth and Planetary Sciences. Annual Reviews. 29: 110–11. Bibcode:2001AREPS..29..109T. doi:10.1146/annurev.earth.29.1.109.
  8. "2: The Geology and Tectonics of the Tohoku Region". Development of Methodologies for the Identification of Volcanic and Tectonic Hazards to Potential HLW Repository Sites in Japan: The Tohoku Case Study (Report). Nuclear Waste Management Organization of Japan. March 2009. NUMO-TR-08-03.
  9. S. Noguchi (December 2003). Two Oceanic Plates Subducting Beneath the Kanto Area and Implications for the Prominent Seismicity Before the 1923 Kanto Earthquake. American Geophysical Union: Fall Meeting 2003. AGU Fall Meeting Abstracts. 2003. San Francisco, CA: American Geophysical Union. pp. S52B–0142. Bibcode:2003AGUFM.S52B0142N.
  10. "Basic Information on Disasters". Chiba Prefectural Police Headquarters. Archived from the original on 24 February 2012. Retrieved 15 April 2012.
  11. Ishibe, Takeo; Shimazaki, Kunihiko; Satake, Kenji; Tsuruoka, Hiroshi (2011). "Change in seismicity beneath the Tokyo metropolitan area due to the 2011 off the Pacific coast of Tohoku Earthquake" (PDF). Earth, Planets and Space. Tokyo: Terra Scientific Publishing Company. 63 (7): 731–34. Bibcode:2011EP&S...63..731I. doi:10.5047/eps.2011.06.001. ISSN 1343-8832.
  12. Haruko Sekiguchi, Masayuki Yoshimi and Haruo Horikawa (23–26 August 2011). Broadband ground motion simulation for great interplate earthquakes with multi-scale heterogeneous source modeling (PDF). 4th International IASPEI/IAEE Symposium on the Effects of Surface Geology on Seismic Motion. Santa Barbara, CA: University of California Santa Barbara.
  13. Earthquakes Off-shore East of Chiba Prefecture in April (Report). Headquarters for Earthquake Research Promotion. May 2011. Retrieved 14 April 2012.
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