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Country: | United States | |
| Subregion Name: | Alaska Peninsula | ||
| Volcano Number: | 1102-17- | ||
| Volcano Type: | Stratovolcano | ||
| Volcano Status: | Historical | ||
| Last Known Eruption: | 1912 | ||
| Summit Elevation: | 2047 m | 6,716 feet | |
| Latitude: | 58.280°N | 58°16'47"N | |
| Longitude: | 154.963°W | 154°57'48"W | |
| Prior to 1912, Mount Katmai was a compound stratovolcano with four NE-SW-trending summits, most of which were truncated by caldera collapse in that year. Two or more large explosive eruptions took place from Mount Katmai during the late Pleistocene. Most of the two overlapping pre-1912 Katmai volcanoes are Pleistocene in age, but Holocene lava flows from a flank vent descend the SE flank of the SW stratovolcano into the Katmai River canyon. Katmai was initially considered to be the source of the Valley of Ten Thousand Smokes ash flow in 1912. However, the 3 x 4 km wide caldera of 1912 is now known to have formed as a result of the voluminous eruption at nearby Novarupta volcano. The steep walled young caldera has a jagged rim that rises 500-1000 m above the caldera floor and contains a 250-m-deep, still-rising lake. Lake waters have covered a small post-collapse lava dome (Horseshoe Island) that was seen on the caldera floor at the time of the initial ascent to the caldera rim in 1916. Post-1912 glaciers have formed on a bench within Katmai caldera. | |||
