A is a

megathrust earthquake Megathrust earthquakes occur at convergent plate boundaries, where one tectonic plate is forced underneath another. The earthquakes are caused by slip along the thrust fault that forms the contact between the two plates. These interplate earthqu ...

occurring in the Kantō region of Japan that originate from slippage in the

Sagami Trough The also Sagami Trench, Sagami Megathrust, or Sagami Subduction Zone is a long trough, which is the surface expression of the convergent plate boundary where the Philippine Sea Plate is being subducted under the Okhotsk Plate. It stretches from ...

. Kantō earthquakes are thought to occur with a 200-year

return period A return period, also known as a recurrence interval or repeat interval, is an average time or an estimated average time between events such as earthquakes, floods, landslides, or river discharge flows to occur. It is a statistical measurement typ ...

. Only two earthquakes in the Kantō region are thought to be megathrust earthquakes: * 1923 Great Kantō earthquake; most common usage *

1703 Genroku earthquake The occurred at 02:00 local time on December 31 (17:00 December 30 UTC). The epicenter was near Edo, the forerunner of present-day Tokyo, in the southern part of the Kantō region, Japan. An estimated 2,300 people were killed by the shaking and ...

Other earthquakes in the Kantō region, which may or may not be due to slippage in the Sagami Trough: *The ''

Ruijū Kokushi is a historical text that categorizes and chronologizes the events listed in the ''Six National Histories''. It was compiled by Sugawara no Michizane and completed in 892. The text was commissioned by Emperor Uda. Contents The text was originall ...

'' mentions an earthquake that struck the area in 818 * 1855 Edo earthquake

See also