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Country: | United States | |
| Subregion Name: | Western Alaska | ||
| Volcano Number: | 1104-02- | ||
| Volcano Type: | Shield volcano | ||
| Volcano Status: | Holocene | ||
| Last Known Eruption: | Unknown | ||
| Summit Elevation: | 511 m | 1,676 feet | |
| Latitude: | 60.02°N * | 60°1'0"N | |
| Longitude: | 166.33°W | 166°20'0"W | |
| Nunivak Island contains about 60 cinder cones and four maars; the surface of the island consists dominantly of thin pahoehoe lava flows that form a carapace over Cretaceous sedimentary rocks. The 110-km-wide permafrost-covered island lies about 30 km off the coast of SW Alaska. The widespread, thin pahoehoe lava flows originate from small shield volcanoes and cover much of the island, which is dotted throughout by cinder cones and other vents. Two of the maars have about 200 m of relief, with floors near sea level. Eruptions occurred during 5 broad periods of activity that began 6.1 million years ago and continued into the Holocene. The bulk of the >427 cu km volcanic field was formed during two Pleistocene eruptive periods that ended about 300,000 years ago. The most recent eruptions at Nunivak produced a series of alkalic basalt lava flows and ash deposits from cinder cones and maars along an E-W zone in the southern part of the island. | |||
