mercredi, mai 30, 2007
According to a news article, "sea surges" destroyed four homes and aboat following an eruption of Ritter Island on 19 May. About 1,500-2,000 peopleon Siassi Island moved to higher ground. Villagers reported seeing plumes from the island, hearing rumbling noises, and feeling earthquakes. The article also mentioned that RVO and the Geophysical Observatory in Port Moresby did not record any seismic activity from the eruption.[details]
Ritter Island volcan éruptions
stratovolcan 140 m / 459 ft
Northeast of New Guinea, Papouasie-Nouvelle Guinée, -5.52°S / 148.12°E
Liste des éruptions: 2007, 2006, 2002(?), 1974, 1972, 1888, 1887, 1793, 1770
The eruption on 19 May was similar to the 1972 and 1974 events, in that it lasted only a few hours and was preceded by explosion sounds followed by the tsunami. The Geophysical Observatory in Port Moresby did not record any seismic activity from the eruption.
Another tsunami was produced on 30 May, reaching heights of 4-10 meters around Ritter Island, mainly on the S part. Scorched vegetation was observed in the same area and dead marine animals, mainly reef fish, around the coastline. No fresh lava could be seen, but a new landslide had occurred on the S tip of island where an portion from the uppermost part of the island (~100 m elevation) down to sea level had been removed. Several other smaller landslide scars were seen on the W wall. Rockfalls continued to produce dust clouds that could be seen from a distance.
Source: Smithsonian / GVP monthly reports
(GVP monthly reports)
As much as 5 km3 of material collapsed, making this the largest historical island volcano collapse in the world. (Its volume is about twice the volume of the 1980 collapse of Mount St Helens).
The westward-directed landslide launched a catastrophic tsunami that hit nearby coasts and caused several hundred fatalities. It spread further to coasts several hundred kilometers distance and caused significant damage.
Steven N. Ward and Simon Day (2003) "Ritter Island Volcano—lateral collapse and the tsunami of 1888", Geophys. J. Int., v 154, pp. 891–902
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