Genroku earthquake

Japanese: 元禄地震 - げんろくじしん

A massive earthquake struck the Kanto region on November 23, 1703 (Genroku 16). The epicenter was located off the southern coast of the Boso Peninsula, at latitude 34.7°N, longitude 139.8°E, and the magnitude of the earthquake was estimated to be 7.9-8.2 on the Richter scale. The seismic intensity was high in areas along Sagami Bay from Odawara to Kamakura, Edo, and the southern part of the Boso Peninsula. Odawara in particular experienced a seismic intensity of 7 and suffered heavy damage, including the destruction of the castle tower of Odawara Castle in a fire that followed the earthquake. The gates, turrets, and storehouses of Edo Castle were also damaged. This earthquake caused a large tsunami to surge along the coast from the Boso Peninsula to the Izu Peninsula, with wave heights estimated at 10m on Oshima Island in the Izu Islands, 5-10m from Sagami Bay to Kujukurihama on the Boso Peninsula, and 2m in the inner Tokyo Bay. In Ito, the tsunami penetrated inland along the river for about 2km. More than 10,000 people were killed in the earthquake and tsunami. Significant uplift was seen from the southern part of the Boso Peninsula to the Miura Peninsula, with Nojimazaki rising by 5m. It is believed to have been a trench-type earthquake caused by the Philippine Sea Plate subducting under the Kanto region from the Sagami Trough, similar to the 1923 Kanto earthquake (→ Great Kanto Earthquake), and was larger in scale than the Kanto earthquake.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

元禄16（1703）年11月23日に関東地方を襲った巨大地震。震央は房総半島南方沖，北緯 34.7°，東経 139.8°で，地震の規模はマグニチュード（M）7.9～8.2と推定されている。相模湾に沿う小田原から鎌倉，江戸，房総半島南部で震度が大きく，特に小田原では震度 7のゆれと地震発生後の火災で小田原城の天守閣が焼失するなど，大きな被害を受けた。江戸城でも門や櫓，土蔵などに被害があった。この地震で，房総半島から伊豆半島にいたる沿岸に大きな津波が押し寄せ，波高は伊豆諸島の大島で 10m，相模湾から房総半島の九十九里浜で 5～10m，東京湾奥で 2mと推定され，伊東では津波が川沿いに 2kmあまり内陸に浸入した。地震と津波で 1万人以上が犠牲となった。房総半島南部から三浦半島にかけて顕著な隆起がみられ，野島崎では 5m隆起した。1923年の関東地震（→関東大震災）と同様に相模トラフから関東地方下に沈み込むフィリピン海プレートが引き起こした海溝型地震で，規模は関東地震より大きかったと考えられている。

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