2005 Miyagi earthquake
  Location within Tohoku, Japan  Location within Japan | |
| UTC time |
|
|---|---|
| ISC event | |
| USGS-ANSS | |
| Local date |
|
| Local time | |
| Duration | 20 seconds |
| Magnitude | |
| Depth |
|
| Epicenter | 38°16′34″N 142°02′20″E / 38.276°N 142.039°E |
| Fault | Japan Trench |
| Areas affected | Tōhoku Region and Saitama Prefecture, Japan |
| Total damage | 985 homes damaged or destroyed |
| Max. intensity | JMA 6− (MMI VII) |
| Peak acceleration | 0.52 g |
| Peak velocity | 31 cm (12 in)/s |
| Tsunami | 10 cm (3.9 in) |
| Landslides | Yes |
| Aftershocks | 19 (as of 31 December 2005) Mw 6.5 on 2 December 2005 (Strongest) |
| Casualties | 100 injured |
On 16 August 2005, at 11:46:28 JST, a MJMA 7.2 earthquake struck off the coast of the Oshika Peninsula in Miyagi Prefecture, Japan.[1] It injured 100 people and damaged nearly 1,000 homes primarily in the Tōhoku Region.
Tectonic setting
The Pacific plate, made of oceanic lithosphere, subducts beneath the Okhotsk Sea plate along a convergent boundary located off the east coast of the northern half of Japan.[2] It runs from the Boso triple junction and ends near Hokkaido, where it joins the Kuril–Kamchatka Trench. At this location, the Pacific plate moves approximately westward relative to the North American plate at a velocity of 70 mm (2.8 in)/yr, subducting beneath Japan at the Japan Trench. This subduction zone is capable of producing megathrust earthquakes with magnitudes greater than 8.5, evident in the historical records. It was on the subduction interface where the 2011 Tōhoku earthquake nucleated. That event involved a rupture 220 km (140 mi) by 400 km (250 mi) on the subduction zone.[3]
Earthquake
Both the United States Geological Survey (USGS) and Japan Meteorological Agency (JMA) recorded a magnitude of Mw 7.2 and MJMA 7.2, respectively. Its offshore epicenter was located 39 km (24 mi) east of the island of Kinkasan in Miyagi Prefecture. The focal mechanism corresponded to thrust faulting on the Japan Trench. A rupture area of 135 km (84 mi) x 60 km (37 mi) was estimated, with a maximum slip of 2.2621 m (7.422 ft) west of the epicenter. The observed source time function gives a 20 second duration for the earthquake, with the greatest phase of seismic moment release occurring about five seconds after initiation.[1]
On the Modified Mercalli intensity scale (MMI), a maximum intensity of VII (Very strong) was recorded at Ishinomaki and areas along the Oshika Peninsula, while in Sendai, the MMI reached VI (Strong). A maximum peak ground acceleration of 0.52 g was recorded at Kurihara, Miyagi, while a station at Yamamoto recorded a peak velocity of 31 cm (12 in)/s.[1]
By the end of 2005, 19 aftershocks of Mw 4.0 or higher were recorded by the USGS;[4] the largest aftershock measured Mw 6.5, striking on 2 December with an epicenter southeast of the mainshock.[5]
A tsunami advisory was issued by the JMA, but was lifted shortly after. A 10 cm (3.9 in) high tsunami struck the Tōhoku Region's coastline.[6]
| Intensity | Prefecture | Locations |
|---|---|---|
| 6- | Miyagi | Kawasaki |
| 5+ | Miyagi | Sendai, Natori, Higashimatsushima, Ishinomaki, Wakuya, Misato, Ōsaki, Kurihara, Tome |
| Fukushima | Kunimi, Sōma, Shinchi, Minamisōma | |
| Iwate | Ichinoseki | |
| 5- | Miyagi | Yamamoto, Kakuda, Watari, Iwanuma, Shibata, Ōsato, Murata, Shiogama, Ōhira, Kami, Minamisanriku, Onagawa |
| Fukushima | Fukushima City, Nakajima, Tamura, Nihonmatsu, Iitate, Date, Koori | |
| Iwate | Rikuzentakata, Hiraizumi, Ōshū, Kanegasaki, Kitakami, Hanamaki, Yahaba, Ninohe | |
| Ibaraki | Hitachi | |
Impact
At least 100 people were injured, 12 of them seriously, including 79 in Miyagi, 11 in Iwate, 5 in Fukushima, 4 in Saitama and 1 in Yamagata. One house partially collapsed in Saitama, while 984 other households suffered partial damage across Honshu, including 590 in Fukushima, 383 in Miyagi, 9 in Iwate and 2 in Akita.[8]
Some people were injured after the roof of an auditorium collapsed in Sendai. One landslide was also reported at an unspecified location.[6] Bullet trains were suspended, three nuclear power stations were shut down automatically for safety checks, and flights at Haneda Airport in Tokyo were temporarily halted as a precaution. Some 17,000 households were reported to have lost power.[6]
See also
References
- 1 2 3 ANSS. "M 7.2 - 66 km ESE of Ishinomaki, Japan 2005". Comprehensive Catalog. U.S. Geological Survey.
- ↑ James D. Kirkpatrick Christie D. Rowe Kohtaro Ujiie J. Casey Moore Christine Regalla Francesca Remitti Virginia Toy Monica Wolfson-Schwehr Jun Kameda Santanu Bose Frederick M. Chester (2014). "Structure and lithology of the Japan Trench subduction plate boundary fault". Tectonics. 34 (1): 53–69. doi:10.1002/2014TC003695. hdl:11380/1062152.
- ↑ Lay, Thorne (2018). "A review of the rupture characteristics of the 2011 Tohoku-oki Mw 9.1 earthquake". Tectonophysics. 733: 4–36. Bibcode:2018Tectp.733....4L. doi:10.1016/j.tecto.2017.09.022.
- ↑ "USGS earthquake catalog". United States Geological Survey.
- ↑ ANSS. "M 6.5 - 80 km ESE of Ishinomaki, Japan 2005". Comprehensive Catalog. U.S. Geological Survey.
- 1 2 3 "Earthquake rocks northern Japan". BBC News. August 16, 2005. Archived from the original on June 13, 2006. Retrieved June 20, 2006.
- ↑ "震度データベース検索". Japan Meteorological Agency. Retrieved July 8, 2021.
- ↑ 宮城県沖を震源とする地震 (確定報) (PDF) (Report) (in Japanese). Fire and Disaster Management Agency. 3 February 2006. Retrieved 8 July 2026.
Further reading
- Kanamori, H; Miyazawa, M; Mori, J (2006). "Special Section for the 2005 M7.2 Miyagi-oki earthquake". Earth Planets Space. 58 (12): 1533–1597. Bibcode:2006EP&S...58.1533K. doi:10.1186/BF03352657.
External links
- Headquarters for Earthquake Research
- Seismological notes from the Earthquake Research Institute, The University of Tokyo
- The International Seismological Centre has a bibliography and/or authoritative data for this event.
