Since 11 February, airplane pilots have reported some steam and ash emission every day (table 1). The highest ash column, on 1 March, was followed by increased activity the next day that ejected ash onto the N flank and deposited fine ash on Akutan village 14 km E of the active cinder cone.

[The following was originally mis-reported as being from Makushin.] On 2 March between 1700 and 1940, a dark eruption plume rose about 900 m above the volcano and drifted SW. After the eruption a 60-m-high steam plume remained.

Geological Summary. Akutan contains a 2-km-wide caldera with a large cinder cone in the NE part of the caldera that has been the source of frequent explosive eruptions and occasional lava effusion that covers the caldera floor. An older, largely buried caldera was formed during the late Pleistocene or early Holocene. Two volcanic centers are located on the NW flank. Lava Peak is of Pleistocene age, and a cinder cone lower on the flank produced a lava flow in 1852 that extended the shoreline of the island and forms Lava Point. The 60-365 m deep younger caldera was formed during a major explosive eruption about 1,600 years ago and contains at least three lakes. A lava flow in 1978 traveled through a narrow breach in the north caldera rim almost to the coast. Fumaroles occur at the base of the caldera cinder cone, and hot springs are located NE of the caldera at the head of Hot Springs Bay valley and along the shores of Hot Springs Bay.

Information Contacts: J. Reeder, ADGGS.