Aniakchak Volcano - John Seach



56.88 N, 158.17 W
summit elevation 1341 m

Aniakchak Volcano is located 30 km SE of Port Heiden, Alaska. The volcano contains a 10 km wide caldera which formed 3400 years ago. The caldera is possibly the most spectacular in the Aleutian arc. The volcano is located in Aniakchak National Monument and Preserve, which is possibly the least visited Park in the US due to its remoteness.

Surprise Lake is located on the NE side of the caldera. It drains through The Gates, a steep-walled breach on the east side of the caldera rim.

Aniakchak contains a 10-km-wide, 1 km deep, circular caldera. The highest point on
the rim of the caldera is almost 1,350 m above sea level, and the lowest point on the caldera floor is about 335 m above sea level.

1931 Eruption
Aniakchak erupted intermittently for nearly two months and ash fell at Holy Cross, 600 km to the north. The eruption was violent, and included both explosive and effusive phases. The first sign of activity was noted about 10 am on 1st May 1931, when residents saw a vigorous, white column of steam ascending above the crater. By midday, residents reported ground shaking, rumbling noises, and the beginning of tephra fall from a large, black mushroom cloud, accompanied by lightning, over the caldera. Earthquakes during the eruption were felt in Chignik, 65 km away.

Aniakchak Volcano Eruptions

1931 West and SW caldera floor
1560 ± 50 NW & S caldera floor (Half Cone, Vent Mountain)
1550? SE caldera floor (New Cone)
1390 NW caldera floor (Half Cone?)
1220 ± 150 NW caldera floor (Half Cone)
1050? Vent Mountain
700 AD ± 300 S & NW caldera floor (Vent Mtn & Half Cone)
460 AD?
200 AD Northern & western caldera floor
350 BC?, 1645 BC ± 10, 2550 BC ± 500, 5250 BC ± 1000

Large caldera-forming eruption 3400 years ago.