Tracking Magma at Alaskan Volcanoes: 2005 - 2011

U.S. Department of the InteriorU.S. Geological Survey

Tracking Magma at Alaskan Volcanoes: 2005 - 2011

J.A. Power, S. G. Prejean, S.D. Stihler, Z. Lu, C.J. Nye, D.J. Schneider, J.T. Freymueller, P.F. Cervelli, S.R. McNutt.

Organization:

KasatochiOkmok

Pavlof

Spurr

Augustine

Redoubt

• Aleutian Arc Volcanoes• AVO Monitoring • Communication• Recent Unrest/Eruptions

1. Spurr (2005)2. Kastochi (2008)3. Augustine (2006)4. Redoubt (2009)5. Okmok (2008)6. Pavlof (2007)

• Summary

Alaskan Volcanic Centers

Alaska Volcano Observatory Monitoring

Monitoring Techniqueso SeismologyoContinuous GPSoRemote Sensing (visual & InSAR)oWebcamsoAirborne Gas (SO2 & CO2)oGeologyoPressureoOthers

Seismic Stations in Alaska

Red = AVO, Yellow = AEIC, Purple = WCATWC, Black = GSN

AVO Volcano Communication

•ALASKA VOLCANO OBSERVATORY

•ALASKA DEPARTMENT OF EMERGENCY SERVICES

•US AIR FORCE

•NOAA/NATIONAL WEATHER SERVICE

•FEDERAL AVIATION ADMINISTRATION

•Others

http://vaac.arh.noaa.gov/interagency_plan.pdf

Mount Spurr: 2005

Historical Eruptions19531992

Crater Peak1953 & 1992 Vent

Spurr Summit~6000 Years BP

Monitoring Equipment9 SP Seismometers3 BB Seismometers

3 CGPS1 Webcam

Anchorage

2004 - 2006

2004 – 2007 Spurr Seismicity is characterized by:1.Shallow VTs beneath Spurr Summit.2.Small magnitudes.3.Deep Long-Period Events to SE.4.Changes in stress direction (D. Roman).

Gas (CO2) Flux Thermal – Snow Melt

Geodesy – CGPS Inflation

Spurr Summit 2005……Unrest is driven by a deep

intrusion marked by DLP and shallow seismicity, snow melt, gas flux, and inflation.

Yellow: July 26, 2004 – January 12, 2006

Photo by Jerry Morris

Kasatochi Volcano: 2008 VEI 4

No Local Monitoring!

Historical EruptionsNone

KasatochiKorovin

Great Sitkin

Explosions

RED, First Explosion

ORANGEM5.6

August 7, 2008August 6, 2008

Closest Seismometer ~ 37 km

YELLOW, Evacuation Effort Started

Evacuation Complete

GOES Band 4m5: 09 Aug 2008 0100 UTC

Ash Cloud on August 9, 2008

Kasatochi in retrospect…Successful forecast was possible because of

large energy release at a long dormant center.

If the volcano had been seismically monitored, we would have had weeks to months of warning.

Kasatochi area seismicity from the AEIC earthquake catalog

May June AugustJulyAprilMarch

2

4

6

Ear

thqu

ake

Mag

nitu

de

2008

Aleutian Volcano Seismic Moment

1 fringe = 11.76 cm

Augustine Volcano: 2006 VEI 3

Historical Eruptions19861976

1963-64193518821812

2006 Monitoring Equipment9 SP Seismometers4 BB Seismometers

5 CGPS

Augustine……The 2006 eruption was proceeded by

8 to 9 months of increasing shallow seismicity, Distal VTs, deformation (inflation), and gas flux. This pattern of precursory activity was similar to the 1986 and 1976 eruptions.

60 Minutes

RED

ORANGE

Fisher et al., 2010

Photo by C. Read

Redoubt Volcano: 2009 VEI 3

Historical Eruptions1989-90

1965 – 6619331902

2009 Monitoring Equipment5 SP Seismometers

5 BB Seismometers (installed 2009)5 CGPS (4 installed in 2009)

Sulfer Smell

DLP Characteristics•Z ~ 28 – 37 km•ML ~ 0.7 – 1.4•SEH ~ 0.5 – 2.5 km•SEZ ~ 1.0 – 3.0 km

Snow Melt

Deformation

Grapenthin, et al., Submitted Geodetic Observations during the 2009 eruption of Redoubt Volcano, Alaska, JVGR, Submitted.

The 2009 eruption was also preceded by a small inflation observed at AC17~30 km northeast of the edifice beginning in July 2008 (Grapenthin et al.Submitted).

January 21 – February 20 February 21 – March 23

Redoubt 2009 Shallow Precursory Seismicity

Redoubt 2009 …… The 2009 Eruption was proceeded by marked increases in

gas flux, deformation, and Deep Long-Period (DLP) seismicity. Short-term forecasting was difficult because of pervasive tremor and swarms of shallow events – a strong contrast to the 1989-90 activity.

6 Hours

Orange

YellowOrange

Red

Okmok Volcano: 2008VEI 4

Photo by C. Read

Historical Eruptions1997198819831981

+ 12 more since 1805

~9.5 km

Monitoring Equipment6 SP Seismometers4 BB Seismometers

4 CGPS

24 Hours

30 Minutes

Eruption Begins

RED

1

3

2

Ear

thqu

ake

Mag

nitu

de

Month in 2008

0

1 2 3 4 5 6 7 8 9 10

Okmok in Retrospect: Very short precursors! 6 hours before eruption: No unusual activity (although some CGPS stations are inoperable). No advance warning was issued! Co-eruption signals are strong!

COLOR CODE: GREEN RED

Subsidence of >50 cm

Okmok Co-Eruption Signals

1 fringe = 2.83 cm

Pavlof Volcano: 2007 VEI 2

Aeromap 1996

Historical Eruptions1996-97

1988198619831981

+ 34 since 1790

Monitoring Equipment6 SP Seismometers

3 d

ays

1 Hour

Pavlof in retrospect…Frequently active or open-vent system that exhibits very

mild precursory activity.

Yellow

Orange

Strombolian Eruption Reported

Neither the 2007 or 1996-97 eruptions show deformation in InSAR, however, CGPS data is not available.

Summary

Kastatochi and Spurr suggest long dormant vents activate over months to years.

Long dormant vents and flank intrusions can involve large release of seismic energy.

Aleutian events suggest deformation (CGPS & InSAR) and DLP seismic events hold promise for extending forecasting window.

Frequently active centers (Okmok & Pavlof) can activate much faster and with very weak short-lived precursors.