Redoubt’s ‘Phantom Unrest’ Could Lead to Eruption

Alaska Volcano Observatory

Information Statement – Friday, October 3, 2008 10:37 AM AKDT (10:37 UTC)

Redoubt Volcano

• Type of Volcano: Stratovolcano
• Coordinates: 60°29’7″ N 152°44’38” W
• Summit Elevation: 10197 ft (3108 m)
• Recent Eruptions:1902, 1966-68, and 1989-90
• Location: Western side of Cook Inlet, about 170 km southwest of Anchorage and 82 km east of Kenai, Alaska
• Current Volcano Alert Level: NORMAL

Current Aviation Color Code: GREEN

Annotated photo of Redoubt Volcano from the north, including features seen on 27 September, 2008.
Picture Date: September 27, 2008 – Image Creator: Kate Bull – Image courtesy of the AVO/ADGGS.
Full Size

What’s up at Redoubt?

Starting September 16, reports of strong hydrogen sulfide odor and loud noises coming from the direction of the volcano were reported. AVO observation flight on September 27 revealed:

• A number of fractures and circular openings in the upper Drift glacier for the first time.
• Scientist noted a strong hydrogen sulfide odor, but onboard instrumentation recorded no sulfur dioxide.
• Fumaroles on top of  domes formed in the 1968 and 1990 eruptions showed more vigorous steaming than the last observation in mid-August.
• AVO’s seismic network detected no abnormal earthquake activity, despite the earlier reports.

AVO believes Redoubt’s increased fumarolic activity and presence of sulfur odors do not suggest an imminent eruption, despite similar observations being made in the  months preceding the 1989-1990 eruption, when seismicity also increased significantly. AVO expects a similar strong increase in seismicity first before an eruption occurs.

Notes:

In the 1989-90 eruption lahar traveling down the Drift River partially inundated the Drift River Oil Terminal facility. Ash plumes produced during the same eruption affected international air traffic with traces of ashfall falling on Anchorage and nearby communities. (AVO)