The 2012 Sanriku earthquake (三陸沖地震, Sanriku oki jishin) occurred near the city of Kamaishi, Japan, on December 7 at 17:18 JST.[9] The magnitude 7.3 shock generated a small tsunami, with waves up to 1 m high, that hit Ishinomaki in Miyagi Prefecture.[10] It occurred at a depth of 36 km within the Pacific plate and was the result of reverse faulting, about 20 kilometres (12 mi) east of the Japan Trench.
Damage
Tsunami
The 1 metre (3.3 ft) tsunami caused a mountain of sandbags to collapse in Ishinomaki.[7] An old man went missing and was found dead on December 14 after he sailed out to sea to try to evacuate from the tsunami in Kuji.[6][7]
Shaking
Some pipeworks were damaged in an old people's facility in Saitama.[1] Some boards in a roof of an elementary school in Ichikai shifted.[11] An elderly lady died of shock at her home in Marumori, and a man died of shock after trying to evacuate from where he was working in Iitate, causing a total of 3 deaths.[6] This earthquake also caused 14 injuries.[7]
Previous earthquakes in Kamaishi
In 2001 and 2008, there were a series of micro earthquakes that could have started the tectonic plate movement that triggered the 2012 Kamaishi earthquake. These small series of earthquakes were a magnitude of about 3–4.9. According to studies, the shocks moved from the outer and deeper limits into the mainshock epicenter. These small earthquakes were a precursor that began the tectonic movement for the 2012 earthquake.[12]