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.
Katmai Caldera (Ivica Miskovic)
Katmai volcano is a large stratovolcano about 10 km in diameter with a central lake-filled caldera whose rim is about 4.2 by 2.5 km in area. The caldera rim has a maximum elevation of 2047 m and in 1975 the lake surface was at an elevation of about 1236 m. The estimated elevation of the caldera floor is about 995 m. The volcano is one of five stratovolcanoes near the Novarupta dome, which was the source of the large Plinian eruption in 1912. The eruption produced voluminous pyroclastic flows and counts as the largest eruption in the 20th century.
Katmai Caldera (Roy Wood)
Much of the volcano is mantled by snow and ice and several valley glaciers radiate out from the flanks and three glaciers originating from the upper caldera walls descend into the crater to the lake. Katmai volcano is built on the sedimentary rocks of the Naknek Formation of Late Jurassic age, which are exposed just west of the caldera rim at an elevation of about 1520 m, as well as north and southeast of the crater.
Katmai Caldera
Ash Covered Glaciers (Roy Wood)
Hallo Bay (Alan Vernon)
Originally posted 2010-09-01 04:46:02.
Nice article, however, the middle photo is Mt Martin, which is the third active volcano south of Mt. Katmai. And I believe the bottom photo is of Trident Volcano during its last eruption which began in 1953. The location it was taken from is probably the flank of Katmai. Mt Mageik is in the far left of the photo.