how strong was the 2011 earthquake in japan
2011 Tōhoku earthquake and tsunami The 2011 earthquake off the Pacific coast of Tōhoku (東北地方太平洋沖地震, Tōhoku-chihō Taiheiyō Oki Jishin) was a magnitude 9.0–9.1 (Mw) undersea megathrust earthquake off the coast of Japan that occurred at 14:46 JST (05:46 UTC) on Friday 11 March 2011,[4][9][10] with the epicentre approximately 70 kilometres (43 mi) east of the Oshika Peninsula of Tōhoku and the hypocenter at an underwater depth of approximately 29 km (18 mi).[4][11] The earthquake is often referred to in Japan as the Great East Japan Earthquake (東日本大震災, Higashi nihon daishinsai)[12][13][fn 1] and is also known as the 2011 Tōhoku earthquake,[28] and the 3.11 earthquake. It was the most powerful earthquake ever recorded in Japan, and the fourth most powerful earthquake in the world since modern record-keeping began in 1900.[10][29][30] The earthquake triggered powerful tsunami waves that reached heights of up to 40.5 metres (133 ft) in Miyako in Tōhoku's Iwate Prefecture,[31][32] and which, in the Sendai area, traveled up to 10 km (6 mi) inland.[33] The earthquake moved Honshu (the main island of Japan) 2.4 m (8 ft) east, shifted the Earth on its axis by estimates of between 10 cm (4 in) and 25 cm (10 in),[34][35][36] increased earth's rotational speed by 1.8µs per day,[37] and generated infrasound waves detected in perturbations of the low-orbiting GOCE satellite.[38] Initially, the earthquake caused sinking of part of Honshu's Pacific coast by up to roughly a metre, but after about three years, the coast rose back and kept on rising to exceed the original height of the coast.[39][40][41][42]
Earthquake prediction M8 gained considerable attention when the 2003 San Simeon and Hokkaido earthquakes occurred within a TIP.[117] In 1999, Keilis-Borok's group published a claim to have achieved statistically significant intermediate-term results using their M8 and MSc models, as far as world-wide large earthquakes are regarded.[118] However, Geller et al.[119] are skeptical of prediction claims over any period shorter than 30 years. A widely publicized TIP for an M 6.4 quake in Southern California in 2004 was not fulfilled, nor two other lesser known TIPs.[120] A deep study of the RTP method in 2008 found that out of some twenty alarms only two could be considered hits (and one of those had a 60% chance of happening anyway).[121] It concluded that "RTP is not significantly different from a naÃ¯ve method of guessing based on the historical rates [of] seismicity."[122]