AVO Logo
Site Map | FAQ |
Alaska Volcano Observatory
Summary | Webcams | Webicorders | RSAM | Activity Notifications | Notification Search | Cleveland | Shishaldin | Pavlof 
You are here: Home > Current Volcanic Activity > Archived Volcano Activity Notifications

AVO Archived Volcano Activity Notifications

2007
December
November
October
September
August
July
June
May
April
March
February
January
2006
December
November
October
September
August
July
June
May
April
March
February
January
2005
December
November
October
September
August
July
June
May
April
March
February
January
2004
December
November
October
September
August
July
June
May
April
March
February
January
2003
2002
2001
2000
1999
1998
1997
1996
December
November
October
September
August
July
June
May
April
March
February
January
1995
1994
1993
1992
December
November
October
September
August
July
June
May
April
March
February
January
1991
1990
1989
ARCHIVED REPORT
Printer friendly version

ALASKA VOLCANOES UPDATE

Friday, January 21, 2000 2:55 PM ADT

(2355 UT)

Shishaldin Volcano:

5445.33' 16358.00'Summit Elevation

9,373 ft (2,857 m)

LEVEL OF CONCERN COLOR CODE

IS GREEN

Investigations of recent seismic data

from Shishaldin volcano reveal

the presence of small explosions

over the past few weeks. The

numbers of explosions have

varied from several to over 200

per day, but no steam or ash

plumes have been observed by

airborne and ground observers.

Also, no thermal anomaly has

been observed in satellite

imagery, indicating that lava has

not reached the surface. It is likely

that the explosions are phreatic,

caused by the flashing of water to

steam. These events may

represent a local hazard within a

few hundred meters of the vent

but do not pose a hazard to

aircraft. The occurrence of these

events does not suggest that the

likelihood of a large explosive

eruption has increased. Therefore,

we are staying at Color Code

GREEN.

AVO is monitoring the situation closely

and will issue further updates as

the situation warrants.

Shishaldin volcano is one of the most

active volcanoes in the Aleutian

arc, erupting at least 29 times

since 1775. The most recent

eruptive period occurred in April-

May 1999. The April 19th eruption

sent an ash plume to over 45,000

ft (13,900 m) ASL. Shishaldin

volcano is located near the center

of Unimak Island in the eastern Aleutians. The cone has a base

diameter of approximately 10

miles (16 km) and a small summit

crater that typically emits a steam

plume with occasional small

amounts of ash.

Alaska Volcanoes:

Seismic activity is monitored in real

time at 21 volcanoes in Alaska.

Some of these volcanoes may

currently display anomalous

seismicity, but they are not

considered to be at a dangerous

level of unrest.

Spurr, Redoubt, Iliamna, Augustine,

Snowy, Griggs, Katmai,

Novarupta, Trident, Mageik,

Martin, Aniakchak, Pavlof, Dutton,

Isanotski, Fisher, Westdahl,

Akutan, Makushin, and Great

Sitkin volcanoes are all at or near

normal levels of background

seismicity.

VOLCANO ALERT LEVELS
NORMAL
Volcano is in typical background, noneruptive state or, after a change from a higher level, volcanic activity has ceased and volcano has returned to noneruptive background state.
ADVISORY
Volcano is exhibiting signs of elevated unrest above known background level or, after a change from a higher level, volcanic activity has decreased significantly but continues to be closely monitored for possible renewed increase.
WATCH
Volcano is exhibiting heightened or escalating unrest with increased potential of eruption, timeframe uncertain, OR eruption is underway but poses limited hazards.
WARNING
Hazardous eruption is imminent, underway, or suspected.

AVIATION COLOR CODES
GREEN
Volcano is in typical background, noneruptive state or, after a change from a higher level, volcanic activity has ceased and volcano has returned to noneruptive background state.
YELLOW
Volcano is exhibiting signs of elevated unrest above known background level or, after a change from a higher level, volcanic activity has decreased significantly but continues to be closely monitored for possible renewed increase.
ORANGE
Volcano is exhibiting heightened or escalating unrest with increased potential of eruption, timeframe uncertain, OR eruption is underway with no or minor volcanic-ash emissions [ash-plume height specified, if possible].
RED
Eruption is imminent with significant emission of volcanic ash into the atmosphere likely OR eruption is underway or suspected with significant emission of volcanic ash into the atmosphere [ash-plume height specified, if possible].

PDF version of these definitions
Contact AVO Privacy Accessibility Information Quality FOIA
URL: avo.alaska.edu/activity/avoreport_archives.php
Page modified: May 27, 2014 10:23
Contact Information: AVO Web Team

twitter @alaska_avo
facebook alaska.avo
email Receive volcano updates by email: USGS VNS