Diverse deformation patterns of Aleutian volcanoes from InSAR

Transcription

1 Diverse deformation patterns of Aleutian volcanoes from InSAR Zhong Lu 1, Dan Dzurisin 1, Chuck Wicks 2, and John Power 3 U.S. Geological Survey 1 Cascades Volcano Observatory, Vancouver, Washington 2 Earthquake Hazards Program, Menlo Park, California 3 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

2 Outline About Aleutian Volcanoes Case Studies with ERS/Envisat/Radarsat- 1/JERS-1/ALOS InSAR imagery Summary Automated Radar Processing System Future directions

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4 Objectives 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.

5 Tracking Magma Accumulation at Westdahl Pre-1964 Lava Westdahl Glacier-capped shield volcano Eruptions: 1964, , and Westdahl Peak 1991 Fissure 1991 Lava 1978 Crater 1964 Lava

6 pre-eruption InSAR images can characterize transient deformation of Westdahl volcano before, during and after the 1991 eruption post-eruption 06/ / / / / / /07/ /28/1991 co-eruption 10 km 09/ / / / / / /21/ /30/ / / / / / / cm

7 Deformation history of Westdahl volcano

8 Magma plumbing system for Westdahl volcano, inferred from InSAR and modeling Sea level Shallow Reservoir ~7 km

9 Transient Deformation of Okmok volcano A breathing volcano Shield volcano Caldera formed 2050 years ago ~10 minor explosive eruptions (ash) in 20 th century 3 large effusive eruptions (basaltic flows ) in 1945, 1958 and 1997 All eruptions from Cone A

10 Transient Deformation of Okmok volcano, Alaska km Subsidence cm 1997 eruption cm Subsidence

11 Magma supply rate at the shallow reservoir 1997 eruption 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 has been replenished.

12 Deformation of 1997 lava flows from JERS-1 Imagery L-band Images Surface displacement due to lava contraction and consolidation could reach 2 mm/day or more 4 months after the emplacement

13 Deformation of lava flows after 1997 eruption Observed Modeled (magma accumulation) Residual = InSAR Image cm 1997 lava flows subside at 5-10 cm/year after the 1997 eruption

14 Dynamic deformation of Seguam volcano 58º 62º Alaska Seguam Volcano: Documented eruptions occurred in , 1827, 1891, 1892, 1901, 1927, 1977, and º o -168º -160º -176º Multi-temporal InSAR Images N 5 km

15 Dominant Source Clusters potential point sources Three clusters dominate, each having a distinctive time-dependent behavior cluster 1 cluster 2 cluster 3

16 Geologic: (based on field observations and laboratory measurements) 0 km W E 7 km to surface directly Magma Plumbing System ~30 km water 0 km Geophysical (this study): (based on InSAR and modeling) W ~30 km E small storage chambers 7 km depth magma Cluster 1 (thermoelastic contraction) Cluster 2 (fluid pressure) Modified from Singer et al., Cluster 3 (magma storage chambers) C1 C2 C3 eruption

17 Deformation Associated With Seismic Swarm Mt Peulik Volcano Becharof Lake Peulik Statovolcanoes Last eruption >150 years ago M5.1 M4.8 Littoral cone M5.2 Ukinrek Marrs Mt Peulik Ugashik Progressive inflation of 24 cm during Seismic swarms in May 1998

18 Deformation Associated Magma Intrusion at Aktuan Akutan The 2 nd most active in the Aleutian arc 27 separate eruptive episodes since 1790 Latest seismic crisis: March 1996

19 Deformation mapped by ERS (C-band, λ = 5.66 cm) InSAR Akutan Volcano 5 km range change cm

20 Deformation mapped by JERS (L-band, λ = cm) InSAR Akutan Volcano 1996 Cracks Akutan 5 km range change cm

21 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.

22 Kiska Summit subsidence (several cm/year) associated with hydrothermal activity (source depth: ~1 km) Volcano Subsidence Fisher 1-2 cm/year subsidence (source depth: 3-5 km) Aniakchak 1.5 cm/year subsidence (source depth: 3-5 km)

23 Insignificant Co-eruptive Deformation? Image covering 1995 eruption Image covering 1998 eruption Shishaldin 3 rd most active volcano In Aleutians. Pre-eruption inflation is compensated by post-eruption deflation Magma accumulation/transfer occur relatively quickly Magma source is very shallow No deformation

24 Frequent eruptions at Cleveland 9/1/2000 9/21/2001 7/27 10/27, km 1-year Envisat interferogram spanning an eruption in km 92-day ALOS interferogram spanning an eruption in 2007 (note: lost coherence)

25 Frequent eruptions at Veniaminof 10 km ERS Stacking: Loss of ALOS coherence over snow/glacier ALOS: 9/5-10/21, 2007 (note: coherence loss)

26 Frequent eruptions at Pavlof ALOS: 7/31-9/15, 2007 (note: loss of coherence) ERS Stacking: km 10 km

27 Deformation of Aleutian Volcanoes from InSAR Korovin Aniakchak Augustine Peulik Tanaga Okmok Lu et al., 2007 Kwoun et al Lu et al. 2002a Lu et al. 2003a Masterlark et al 2006 Lee et al., 2007 Shishaldin cm Lu et al. 2000a, 2003c, 2005a; Mann et al. 2002; Patrick et al., 2003 Kiska Seguam Makushin Akutan Lu et al. 2003a Moran et al Westdahl Lu et al. 2002b Lu et al. 2003a Masterlark & Lu, 2004 Lu et al. 2002c 0 12 cm Lu et al. 2000c, 2005b Lu et al. 2000b, 2003b, 2004

28 Volcano Dancing Diverse Styles, Different Rhythms 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.

29 Radar Processing System (RPS) 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.

30 Future Directions 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

31 Thank you