Alert level raised at Redoubt 22 March 2009Posted by admin in activity reports, Alaska, Redoubt, United States.
Tags: Alaska, Redoubt, United States, volcanic activity reports
UPDATE: Redoubt erupted at 22:36 local time on 22 March 2009 – Redoubt erupts.
Seismic activity is increasing at Mount Redoubt, reports the Alaska Volcano Observatory, and the alert level has been raised again to Aviation Colour Code Orange, Volcano Alert Level Watch. A 300-metre (1000 ft) steam plume has been visible above the summit via the Hut webcam. As we reported here yesterday, the frequency and amplitude of discrete earthquakes have been increasing since around 10:00 local time on 20 March. That increase has become much more marked over the last 10-12 hours, as the RSO Webicorder trace shows:
There is no sign of volcanic tremor: these are small, discrete quakes, currently occurring at a rate of several per minute. Furthermore, the AVO reports that these quakes are ‘shallow’ in depth – although there is no indication how shallow, or whether they are becoming shallower with the passage of time, which would indicate magma ascending the conduit.
In a status report issued at 13:23 local time (21:23 GMT) yesterday, the AVO reported that ‘Shallow earthquake activity under the volcano that began yesterday continues’, and that ‘A steam plume rising as high as approximately a thousand feet above the volcano is visible on the web cameras, but no explosive or ash activity such as occurred last Sunday has been identified’. At 22:09 local time yesterday (06:09 GMT 22 March 2009) a Volcanic Activity Notice was issued upgrading the alert status to Orange/Watch and stating: ‘AVO is raising the aviation color code to Orange and the alert level to Watch. Seismic activity has continued to increase and conditions may evolve rapidly culminating in an eruption within days to weeks’.
At the time of posting the latest AVO observations (2009-03-22 04:53:43) read: ‘Seismicity remains elevated with several small events occurring each minute. We are watching closely. There are numerous small events and size of the events has increased a bit’.
UPDATE: Check out Akira Shirakawa’s video of yesterday’s activity at Redoubt – some vigorous steaming captured by the Hut webcam.
UPDATE: The latest observations from the AVO (2009-03-22 08:45:06) – ‘Seismicity rates have increased dramatically over the last 48 hours. Currently, the earthquake rate is about 40 to 50 events per hour. Many of these events are large enough to be recorded at the more distal stations of the Redoubt network, including NCT and DFR’.
For all our Redoubt coverage: Redoubt « The Volcanism Blog.
Global Volcanism Program: Redoubt – summary information for Redoubt (1103-03-)
Alaska Volcano Observatory – Redoubt – AVO information and updates for Redoubt
Alaska Volcano Observatory – main page for the AVO