(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA)
(2) Issued:(20080807/0317Z)
(3) Volcano:Kasatochi (CAVW# 1101-13-)
(4) Current Color Code:YELLOW
(5) Previous Color Code:
(6) Source:Alaska Volcano Observatory
(7) Notice Number:2008/A22
(8) Volcano Location:N 52 deg 10 min W 175 deg 30 min
(9) Area:Aleutians Alaska
(10) Summit Elevation:1030 ft (314 m)
(11) Volcanic Activity Summary:Over the past 12 hours earthquake activity in the greater vicinity of Kasatochi volcano has increased rapidly. Earthquakes are poorly located, and it is possible that the earthquakes are associated with submarine activity. A US Fish and Wildlife Service field crew on Kasatochi Island has reported continual small tremors over the past several days. AVO is elevating the color code at Kasatochi to YELLOW due to the possibility that these earthquakes may result from magma movement toward the surface. The swarm-like character of the seismicity suggests that the activity may be related to the intrusion of magma which may or may not culminate in eruptive activity.

Earthquake locations are very poor due to the lack of seismic monitoring in this area. There are no seismic instruments on Kasatochi Island and we are detecting the earthquakes on neighboring networks.

(12) Volcanic cloud height:Unknown
(13) Other volcanic cloud information:Unknown
(14) Remarks:Kasatochi Island represents the emergent summit of a predominantly submarine volcano composed of basaltic and andesitic flows and pyroclastics. The island consists of a single, undissected cone with a central lake-filled crater about 0.75 km in diameter. A maximum height of 314 m is on the southern crater rim; elevation of the lake is less than about 60 m. Kasatochi Island is at the northern end of a 15-km-long, 6-km-wide submarine ridge that is normal to the trend of the Andreanof Islands. Water depths along the ridge are less than 90 m; if Kasatochi is constructed entirely on the ridge, the total height of the volcanic pile is only a little more than 400 m.
(15) Contacts:Chris Waythomas, Acting Scientist-in-Charge, USGS
chris@usgs.gov (907) 786-7497

Jon Dehn, Acting Coordinating Scientist, UAFGI
dehn@gi.alaska.edu (907) 474-6499
(16) Next Notice:A new VONA will be issued if conditions change significantly, alert levels are modified, or if new information becomes available. While a VONA is in effect, regularly scheduled updates are posted at http://www.avo.alaska.edu