sexta-feira, novembro 04, 2011

Um dos maiores sismos do século XX ocorreu há 59 anos

(imagem daqui)

Three Kamchatka earthquakes, which occurred off the coast of Kamchatka Peninsula in far eastern Russia in 1737, 1923 and 1952, were megathrust earthquakes and caused tsunamis. They occurred where the Pacific Plate subducts under the Okhotsk Plate at the Kuril-Kamchatka Trench. The depth of the trench at the point of the earthquakes is 7,000–7,500 meters. Northern Kamchatka lies at the western end of the Bering fault, between the Pacific Plate and North American Plate, or the Bering plate There are many more earthquakes and tsunamis originating from Kamchatka, of which the most recent was the 1997 Kamchatka earthquake and tsunami originating near the Kronotsky Peninsula.

1952 earthquake
The main earthquake struck at 16:58 GMT (04:58 local time) on November 4, 1952. Initially assigned a magnitude of 8.2, the quake was revised to 9.0 Mw in later years. A large tsunami resulted, causing destruction and loss of life around the Kamchatka peninsula and the Kuril Islands. Hawaii was also struck, with estimated damages of up to US$1 million and livestock losses, but no human casualties were recorded. Japan also reported no casualties or damage. The tsunami reached as far as Alaska, Chile, and New Zealand.
The hypocentre was located at 52.75°N 159.5°E, at a depth of 30 km. The length of the subduction zone fracture was 600 km. Aftershocks were recorded in an area of approximately 247,000 km2, with epicenters at depths of between 40 and 60 km. A recent analysis of the tsunami runup distribution based on historical and geological records give some indication as to the slip distribution of the rupture.


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