The 1930 North Izu earthquake (1930年北伊豆地震, ''Sen-kyūhyaku-sanjū-nen Kita-Izu Jishin'') occurred on . The epicenter was located in the northern

Izu Peninsula The is a large mountainous peninsula with a deeply indented coastline to the west of Tokyo on the Pacific coast of the island of Honshu, Japan. Formerly known as Izu Province, Izu peninsula is now a part of Shizuoka Prefecture. The peninsul ...

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

. It had a magnitude of 7.3, and was caused by the movement of the Tanna Fault (丹那断層).

Geology

The

is located in the northern tip of the Philippine Sea Plate. However, the GPS vectors of the Izu Peninsula are almost westwards, which are different from the northwestward motion of the Philippine Sea Plate. A seismically active area in the east off the Izu Peninsula might be the deformation zone between the Izu Peninsula and the main part of the Philippine Sea Plate or at times be regarded as the boundary between the Izu microplate and the Philippine Sea Plate. The suspected boundary may be a complex fracture zone than a simple boundary. In this view, the Izu microplate is pushed northwestwards by the Philippine Sea Plate and rotates clockwise, pivoting on the base of the Izu Peninsula. The rotation causes an almost westward motion under the

Suruga Bay Suruga Bay (駿河湾, ''Suruga-wan'') is a bay on the Pacific coast of Honshū in Shizuoka Prefecture, Japan. It is situated north of a straight line from Omaezaki Point to Irōzaki Point at the tip of the Izu Peninsula and surrounded by Honshū ...

. The interplate coupling under the Sugura Bay is not weak. The Tanna Fault is part of the North Izu Fault Zone (or Kita-Izu Fault Zone) (北伊豆断層帯). The North Izu Fault Zone is about long, lying in the NNE-SSW direction. This fault zone is predominantly of left-lateral strike-slip faulting with an estimated left-lateral slip rate of about per 1000 years. The 1930 North Izu earthquake was identified with the movement of the Tanna Fault. The

focal mechanism The focal mechanism of an earthquake describes the deformation in the source region that generates the seismic waves. In the case of a fault-related event it refers to the orientation of the fault plane that slipped and the slip vector and is ...

was left-lateral strike-slip faulting.

Damage

Two hundred and seventy-two people were reported dead in this earthquake. 2,165 houses were totally destroyed. Building damage rate was high along the Tanna Fault. Many buildings collapsed in the village of Kawanishi (川西村), now part of Izunokuni,

Shizuoka Shizuoka can refer to: * Shizuoka Prefecture, a Japanese prefecture * Shizuoka (city), the capital city of Shizuoka Prefecture * Shizuoka Airport * Shizuoka Domain, the name from 1868 to 1871 for Sunpu Domain, a predecessor of Shizuoka Prefecture ...

. The earthquake caused many landslides. A landslide caused 15 deaths in the village of Nakakano (中狩野村), and another one caused 8 deaths in the village of Kitakano (北狩野村), both locations now belong to Izu, Shizuoka. The intensity reached shindo 6 in

Mishima Mishima may refer to: Places * Mishima, Fukushima, a town in Fukushima Prefecture * Mishima, Kagoshima, a village in Kagoshima Prefecture * Mishima, Niigata, a town in Niigata Prefecture * Mishima, Shizuoka, a city in Shizuoka Prefecture, Japan ...

, Shizuoka. Fires were reported in Itō, Shizuoka.

Related earthquakes

The change of the Coulomb failure stress due to the 1923 Kantō earthquake may have had contribution to the occurrence of this earthquake. There was an earthquake swarm near Itō, Shizuoka from February 13 to the end of May, 1930, to which the November 26 earthquake was not thought to belong. The largest foreshock of this earthquake occurred on November 25, 1930, at 16:05 local time, and the largest aftershock occurred on March 7, 1931, at 01:53 local time.

Earthquake light

A prominent

earthquake light An earthquake light is a luminous aerial phenomenon that reportedly appears in the sky at or near areas of tectonic stress, seismic activity, or volcanic eruptions. There is no broad consensus as to the causes of the phenomenon (or phenomena) inv ...

was observed. It could be observed over a large area, including the coast of Suruga Bay, the Izu Peninsula, the coast of Sagami Bay, Sagami River Valley, the coast of Tokyo Bay, and the Bōsō Peninsula. The earthquake light was reported to have appeared before the earthquake occurred and continued for at least an hour.

References

External links