Shishaldin Volcano

Shishaldin volcano (2857m) is a frequently active nearly perfectly conical stratovolcano located adjacent to the inactive Isanotski and Roundtop volcanoes on Unimak Island, Alaska. Unimak is the first of the Aleutian Islands and is located over 1000 km SW of Anchorage. Due to its remote location, historical records of activity are patchy and the impact of activity on humans is negligible. However, larger ash eruptions can pose a hazard to aviation along the busy Asia to US flying corridor. Usual activity at Shishaldin involves continuous degassing at the summit crater, often resulting in a small characteristic white plume.

Shishaldin Volcano viewed from SE, September 2007	Glaciated summit region of Shishaldin volcano

Summit crater of Shishaldin with characteristic steam emission	Summit crater of Shishaldin with characteristic steam emission

Shishaldin is primarily basaltic in composition and has grown in the last 10000 years within an older glacially disected volcano of which remnants are still visible mostly on the W flank.  Recent activity has predominantly involved minor explosive eruptions from the summit crater (e.g. 1993, 1995, 1997, 1999, 2004).  Eruptions may also involve lava flows and lahars, resulting from melting of the ice which usually coats the top half of the volcano.  In fact, about 30% of historical eruptions have involved lava flows, mainly emanating from the summit crater.  However, flank eruptions were reported in 1825 and 1929, with effusion occurring on NE and N flanks respectively.  The NW flank is indeed the site of over 20 parasitic cones, representing the sites of earlier eruptions. 

View over Isanotski to Shishaldin Volcano.	View over Isanotski to Shishaldin Volcano.	Summit of Shishaldin with Roundtop (left) and Isantski (right) behind

The Spring 1999 eruption was probably the most violent since the eruptions of 1830 and 1932.  Over 40 Million cubic meters of tephra are estimated to have been erupted between March 13 and May 27, during a series of largely explosive episodes at the summit crater.  The eruption peaked on April 19, where during a 7 hour period, ash columns reached an altitude of 15-20 km.  The eruption involved numerous further episodes of strombolian activity and lava fountaining at the summit, accompanied by ash columns of various heights.

Shishaldin volcano is located in a remote area near the end of the Alaskan Peninsula and is most easily viewed by chartering a small aircraft from Cold Bay airport which can be reached by regular flights from Anchorage.

For information on further Alaskan volcanoes, see sections on Augustine, Douglas and Fourpeaked.

Further Photos

Photovolcanica Full Index