You are currently browsing the monthly archive for March 2009.

Update: Since the DoS attack does not seem to be materializing, I’ve tentatively brought the network back online, but will continue to monitor.

Due to Conficker concerns, my network will be offline until April 2, or its determined that the threat is bogus. Radar updates are suspended during this time. As the web pages are hosted off site, they may or may not be updated from the external sources linked.

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Redoubt has been mostly quiet today. Further monitoring is underway, and can be followed at the Alaska Volcano Observatory.

This short range composite radar scan was captured by EWRadar last evening at 1:59 EDT (5:59UTC). A long plume can be seen extending northwest from the volcano. The NWS nexrad is not picking up higher elevation returns (in weather service). Whether that’s due to lack of returns or absorption of the returns is not clear. There is a suggestion that ash drop is fairly rapid, thinning out the density. Echo Tops doesn’t return reported plume altitudes either.

redoubt

For technical background on Redoubt, the USGS has an excellent report prepared after the 1989 eruption, entitled Preliminary Volcano-Hazard Assessment for Redoubt Volcano, Alaska. This is an great primer on volcano structure and behavior for newbies as well (pdf, 2mb)

Due to weather changes in our home area, I’ll probably switch off Redoubt tomorrow, unless things get exciting.

Unfortunately, my ISP went offline overnight and locked up my FTP cycles, resulting in no updates after 2 AM EDT. There apparent was a venting or an eruption about midnight EDT as evidenced by the northwesterly plume on the 1:59 scan. I’ll put it up here later today.

I have the NWS nexrad radar up on EWR (sidebar) on Anchorage/Kenai. Presently there is little activity and the weather in the vicinity of the peak is apparently poor vis. The AVO confirms ash plumes should be visible on NWS radar if not too fine and at heights greater than 13,000ft. You’ll note Redoubt is quite close to Anchorage. The following is today’s sitrep from the Alaska Volcano Observatory:
“Current Status and Observations
Beginning last night (Sunday March 22, 2009) at approximately 22:38 AKDT, Redoubt Volcano produced a series of five explosive eruptions that each lasted from four to thirty minutes. The last one ended at 5:00 AM AKDT this morning (March 23). National Weather Service radar, pilot reports, and AVO analysis of satellite imagery suggest that these events produced ash clouds that reached 60,000 ft above sea level (asl), with the bulk of the ash volume between 25 – 30,000 ft asl. Traces of ash fall have been reported in Skwentna, Talkeetna, Wasilla, and Trapper Creek.

AVO remains at Avation Color Code RED and Alert Level WARNING. Seismic unrest continues at Redoubt in the form of elevated volcanic tremor. NEXRAD radar data show that the last significant ash emission was concurrent with the final explosive event at 5:00 AM AKDT. Since that time, no ash has been visible in radar, suggesting that if ash emission is occurring, it is below approximately 13,000 ft asl and/or too fine to be detected. Poor weather at the volcano currently hinders visual observations.

Last night’s explosive eruptions caused melting of the Drift glacier and greatly increased discharge down the Drift River. AVO plans a helicopter overflight to the area today to assess conditions at the volcano and along the Drift River. The explosions also destroyed one seismic station near the volcano’s summit (RSO), and disrupted telemetry from AVO’s obsveration hut. This telemetry outage affects the web camera, a continuous GPS station, and two broadband seismic stations. Repairs to this data link will be undertaken as conditions permit. Seven telemetered seismic stations surrounding Redoubt remain in operation.

The eruptions were preceded by approximately 60 hours of elevated seismicity in the form of discrete earthquakes under the volcano. AVO raised the Aviation Color Code/Alert Level from YELLOW/ADVISORY to ORANGE/WATCH on Saturday, March 21 at 22:09 AKDT. This increase in seismicity likely reflected the upward movement of magma towards the surface. Prior to this weekend, Redoubt had exhibited signs of volcanic unrest beginning in the Fall of 2008 which then escalated in late January, 2009. Last night’s explosions were the first significant ash-producing eruptions of the unrest.

Further explosive activity could occur with little or no warning, and could occur intermittently for weeks or months. AVO remains staffed 24 hours per day will issue further information as it becomes available.

For up-to-date Ashfall Advisories and wind trajectories, please refer to the National Weather Service website: http://pafc.arh.noaa.gov/volcano.php

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