| (1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA) | |
| (2) Issued: | (20100412/2110Z) |
| (3) Volcano: | Redoubt (VNUM #313030) |
| (4) Current Color Code: | GREEN |
| (5) Previous Color Code: | YELLOW |
| (6) Source: | Alaska Volcano Observatory |
| (7) Notice Number: | 2010/A3 |
| (8) Volcano Location: | N 60 deg 29 min W 152 deg 44 min |
| (9) Area: | Cook Inlet-South Central |
| (10) Summit Elevation: | 10197 ft (3108 m) |
| (11) Volcanic Activity Summary: | Seismic activity at Redoubt has diminished significantly from early last week. Based on this decline and the lack of continuing signs of unrest, AVO is lowering the Aviation Color Code and Volcano Alert Level at Redoubt Volcano to GREEN/NORMAL. The swarm of small, shallow earthquakes that began Monday April 5 has ceased and seismic activity beneath the volcano has returned to background levels. Aerial observations of the new lava dome on April 8 and 9 indicated no significant changes at the surface and no sign of instability. Scattered patches of discolored snow and ice on the south side of the mountain may represent wind-remobilized rockfall debris or ash from the 2009 eruption. Alternatively, periods of more vigorous gas emission may entrain small amounts of tiny dome rock fragments that are carried over the crater rim. Most of the dome surface is snow covered although there are areas of continued high-temperature gas emission. Measured levels of magmatic gas emission on April 8 and 9 are below those measured in December 2009, a trend expected for a slowly cooling and degassing lava dome. |
| (12) Volcanic cloud height: | |
| (13) Other volcanic cloud information: | |
| (14) Remarks: | AVO will continue to monitor conditions at Redoubt, but while we have no volcanoes at elevated color codes or alert levels, we will cease our usual daily reporting of activity and instead transmit a weekly summary only. Heavily ice-mantled Redoubt volcano is located on the western side of Cook Inlet, 170 km (106 mi) southwest of Anchorage and 82 km (51 mi) west of Kenai, within Lake Clark National Park. Redoubt is a stratovolcano which rises to 10,197 feet above sea level. Recent eruptions occurred in 1902, 1966-68, 1989-90, and 2009. The 1989-90 and 2009 eruptions produced mudflows, or lahars, that traveled down the Drift River and partially flooded the Drift River Oil Terminal facility. The ash plumes produced by the 1989-90 and 2009 eruptions significantly disrupted air traffic and resulted in minor or trace amounts of ash in the city of Anchorage and other communities in south-central and interior Alaska. |
| (15) Contacts: | Chris Waythomas, Acting Scientist-in-Charge, USGS cwaythomas@usgs.gov (907) 786-7497 Jessica Larsen, Acting Coordinating Scientist, UAF faust@gi.alaska.edu (907)322-4085 |
| (16) Next Notice: | A new VAN will be issued if conditions change significantly or alert levels are modified. While a VAN is in effect, regularly scheduled updates are posted at http://www.avo.alaska.edu |