Diverse deformation patterns of Aleutian volcanoes from...
Transcript of Diverse deformation patterns of Aleutian volcanoes from...
Diverse deformation patterns of Aleutian volcanoes from InSAR
Zhong Lu1, Dan Dzurisin1, Chuck Wicks2, and John Power3
U.S. Geological Survey1 Cascades Volcano Observatory, Vancouver, Washington2 Earthquake Hazards Program, Menlo Park, California3 Alaska Volcano Observatory, Alaska
Acknowledgements:• ESA Projects AO-567, CAT-2765• Funding from USGS and NASA.• Contributions by many colleagues (O. Kwoun, D. Mann, J. Freymuller, W. Thatcher, S. Moran,
T. Masterlark, R. Rykhus, …)• SAR images from ESA, Alaska Satellite Facility, and JAXA
Outline• About Aleutian Volcanoes
• Case Studies with ERS/Envisat/Radarsat-1/JERS-1/ALOS InSAR imagery
• Summary
• Automated Radar Processing System
• Future directions
• Conduct systematic InSAR-based deformation study of volcanoes in the Aleutian volcanic arc;
• Study the eruption cycle at selected volcanoes by monitoring ground deformation before, during, and after eruptions;
• Develop techniques for the analysis, visualization, and modeling of volcano deformation data in near-real time;
• Combining InSAR observations, data modeling and other geophysical/geological data to construct magma plumbing systems at each volcano;
• The ultimate goal is better understanding of the mechanisms of volcanic unrests, which will enable longer-term forecasts and more effective mitigation of volcano hazards.
Objectives
1978 Crater
1991 Lava
Westdahl Peak
1991 Fissure
Pre-1964 Lava
1964 Lava
Westdahl• Glacier-capped shield volcano• Eruptions: 1964, 1978-79, and 1991-92
Tracking Magma Accumulation at Westdahl
06/1992 – 09/1993
09/1992 – 09/1993
09/1993 – 08/1995 10/1997 – 08/1999
10/1995 – 10/1998
10/1993 – 08/1995 08/1999 – 08/2000
10/1992 – 10/1997
09/1993 – 10/1998
post-eruption
11/21/1991 – 11/30/1991
co-eruption
InSAR images can characterize transient deformation of Westdahl volcano before, during and after the 1991 eruption
09/07/1991 – 10/28/1991
pre-eruption
0 2.83 cm
10 km
Def
orm
atio
n hi
stor
y of
Wes
tdah
l vol
cano
Magma plumbing system for Westdahl volcano, inferred from InSAR and modeling
~7 km
Sea level
Shallow Reservoir
• Shield volcano• Caldera formed 2050 years ago• ~10 minor explosive eruptions (ash) in 20th century• 3 large effusive eruptions (basaltic flows ) in 1945, 1958 and 1997• All eruptions from Cone A
Transient Deformation of Okmok volcano – A breathing volcano
1997-1998 1998-1999 1999-2000 2000-2001 2001-2002
Transient Deformation of Okmok volcano, Alaska
2002-2003 2003-2004
10 km
2005-20062004-2005
0 28.3 cm
0 2.83 cm
1992-1993 1993-1995 1995-1996 1996-1997
Subsidence
Subsidence
1997 eruption
2006-2007
Magma supply rate at the shallow reservoir
• A magma reservoir residing at 3.2 km beneath the center of the caldera, is responsible for the observed deformation before, during and after the 1997 eruption.
• By Fall 2007, 60~80% of the magma volume lost from the reservoir in the 1997 eruption hasbeen replenished.
1997 eruption
Deformation of 1997 lava flows from JERS-1 Imagery
L-ba
nd Im
ages
Surface displacement due to lava contraction and consolidation could reach 2 mm/day or more 4 months after the emplacement
Modeled (magma accumulation)
=
Observed Residual
Deformation of lava flows after 1997 eruption
0 2.83 cm
2001-2002 InSAR Image1997 lava flows subsideat 5-10 cm/year after the 1997 eruption
Dynamic deformation of Seguam volcanoSeguam Volcano: Documented eruptions occurred in 1786-1790, 1827, 1891, 1892, 1901, 1927, 1977, and 1992-1993.
62º
54º
58º-1
68º
-176
º
-160
º
Alaska
o
N 5 km
Multi-temporal InSAR Images
cluster 1cluster 2 cluster 3
potential point sources…
Three clusters dominate, each having a distinctive time-dependent behavior
Dominant Source Clusters
mag
ma
small storagechambers
0 km
7 km
E
dept
h
Modified from Singer et al., 1992.
W
to surface
Geologic: (based on field observations and laboratory measurements)
~30 km
directly
water
Magma Plumbing System
Cluster 1(thermoelastic contraction)
Cluster 2(fluid pressure)
Cluster 3(magma storage chambers)
0 km
7 km
W E
Geophysical (this study): (based on InSAR and modeling)
~30 km
C1 C2
erup
tion
C3
Deformation Associated With Seismic Swarm
Peulik• Statovolcanoes• Last eruption >150 years ago
M5.1
M5.2
Littoral cone
Ukinrek Marrs
Mt Peulik
Becharof Lake
Ugashik
M4.8
Mt Peulik Volcano
• Progressive inflation of 24 cm during 1996-1998• Seismic swarms in May 1998
Akutan•The 2nd most active in the Aleutian arc
• 27 separate eruptive episodes since 1790
• Latest seismic crisis: March 1996
Deformation Associated Magma Intrusion at Aktuan
Deformation mapped by ERS (C-band, λ = 5.66 cm) InSAR
0 11.76 cmrange change
5 km
Akutan Volcano
5 km0 11.76 cm
Akutan
1996 Cracks
Deformation mapped by JERS (L-band, λ = 23.53 cm) InSAR
range change
Akutan Volcano
Observed and modeled deformation images
Observed Modeled
Deformation sources:
• b1: a shallow expanding source representing intrusion of magma.• b2, b3, & b4: contracting sources that together account for observed subsidence of the eastern part of the island.
Volcano Subsidence
AniakchakKiska FisherSummit subsidence (several cm/year) associated with hydrothermal activity(source depth: ~1 km)
1-2 cm/year subsidence (source depth: 3-5 km)
1.5 cm/year subsidence (source depth: 3-5 km)
Insignificant Co-eruptive Deformation?
Shishaldin3rd most active volcanoIn Aleutians.
1993-1996 Imagecovering 1995 eruption
1998-1999 Imagecovering 1998 eruption
• Pre-eruption inflation is compensated by post-eruption deflation
• Magma accumulation/transfer occur relatively quickly
• Magma source is very shallow• No deformation• …
10 km
9/1/2000 – 9/21/2001
1-year Envisat interferogramspanning an eruption in 2001
92-day ALOS interferogram spanning an eruption in 2007 (note: lost coherence)
10 km
7/27 – 10/27, 2007
Frequent eruptions at Cleveland
10 km
ALOS: 9/5-10/21, 2007(note: coherence loss)
Loss of ALOS coherence over snow/glacier
Frequent eruptions at Veniaminof
ERS Stacking: 1992-2000
ERS Stacking: 1992-2000
10 km
ALOS: 7/31- 9/15, 2007(note: loss of coherence)
10 km
Frequent eruptions at Pavlof
Deformation of Aleutian Volcanoes from InSAR
Shishaldin
Lu et al. 2003aMoran et al. 2006
Seguam
Lu et al. 2003aMasterlark & Lu, 2004
Lu et al. 2000c, 2005b
Westdahl
Lu et al. 2000b, 2003b, 2004
Makushin
Lu et al. 2002c0 12 cm
AkutanKiska
Lu et al. 2002b
0 28.3 cm
Okmok
Lu et al. 2000a, 2003c, 2005a;Mann et al. 2002;Patrick et al., 2003
Augustine
Lu et al. 2003aMasterlark et al 2006Lee et al., 2007
Peulik
Lu et al. 2002a
Tanaga
Korovin
Kwoun et al. 2006
Aniakchak
Lu et al., 2007
• InSAR’s all-weather, large-area imaging capability makes it particularly useful for studying a variety of volcanic processes by analyzing surface deformation patterns.
• InSAR is an excellent technique for identifying restless volcanoes long before seismic or other precursory signals are detected.
• InSAR can image deformation in two spatial dimensions over a large region, which makes it an attractive tool for studying a complex deformation field.
• Deformation patterns at the Aleutian volcanoes are diverse. Diverse deformation patterns reflect the fact that Aleutian volcanoes span a broad spectrum of eruptive styles, sizes, magma compositions, and local tectonic settings.
• Differing deformation patterns suggest different magma plumbing systems.
Volcano Dancing –Diverse Styles, Different Rhythms
• RPS utilizes state-of-the-art database approach for SAR and InSAR processing, representing a significant departure and advancement from current InSAR processing which is accomplished using a variety of programs and scripts.
• RPS can semi-automatically process large amounts of SAR data for deformation map production.
• RPS provides a SAR data management system - capable of cataloging, archiving and retrieving the processed images and deformation maps.
• A web-based graphic user interface (GUI) that is independent of computer platforms has been developed to interface RPS so that InSAR processing and deformation map generation are accomplished through a few simple steps of shopping-basket procedures.
• RPS lays out the foundation for real-time processing of InSAR images to monitor volcano deformation, and provides a base capability from which to build.
Radar Processing System (RPS)
– Future studies will focus on synthesize the deformation in Aleutian as a “system” and take into account geochemical, geological and geophysical observations.
– Develop techniques to remove atmospheric delay anomalies• Continuous GPS and weather models
– Develop advanced InSAR techniques (PSInSAR and ScanSAR InSAR) for ground deformation imaging
– Develop innovative deformation modeling methods– Refine RPS for volcano deformation monitoring
Future Directions
Thank you