RECENT ADVANCES IN SEISMIC AND INFRASONIC ANALYSES OF VOLCANIC ERUPTIONS AND POTENTIAL FOR USING EARTHSCOPE DATA

Transcription

1 RECENT ADVANCES IN SEISMIC AND INFRASONIC ANALYSES OF VOLCANIC ERUPTIONS AND POTENTIAL FOR USING EARTHSCOPE DATA DAVID FEE WILSON ALASKA TECHNICAL CENTER, ALASKA VOLCANO OBSERVATORY GEOPHYSICAL INSTITUTE, UNIVERSITY OF ALASKA FAIRBANKS ROBIN MATOZA DEPARTMENT OF EARTH SCIENCE AND EARTH RESEARCH INSTITUTE UC SANTA BARBARA MATT HANEY U.S. GEOLOGICAL SURVEY, ALASKA VOLCANO OBSERVATORY 1

2 MOTIVATION AND AIM Arrival of Earthscope in Alaska provides opportunity to study and improve monitoring of volcanic eruptions This talk: 1. Highlight recent advances in seismic and infrasonic analyses of volcanic eruptions 2. Discuss potential of using Earthscope data for monitoring and studying volcanic eruptions Okmok Volcano, 2008 (AVO) 2

3 POTENTIAL VOLCANIC HAZARD RELATED USES OF EARTHSCOPE SEISMIC AND INFRASOUND DATA Volcanoes in AK >90 volcanoes active in Holocene, >50 have erupted in past 200 years >2 eruptions per year Most volcanoes are remote, so primary hazard is aviation Monitored by Alaska Volcano Observatory (AVO) using combination of seismic, infrasonic, geodetic networks, as well remote sensing, geological and geochemical studies 3

4 POTENTIAL VOLCANIC HAZARD RELATED USES OF EARTHSCOPE SEISMIC AND INFRASOUND DATA Recent Eruptions Pavlof: 2013 and 2014 Veniaminof: 2013 Cleveland: 2013 and 2014 Shishaldin:

5 POTENTIAL VOLCANIC HAZARD RELATED USES OF EARTHSCOPE SEISMIC AND INFRASOUND DATA Recent Eruptions Pavlof: 2013 and 2014 Veniaminof: 2013 Cleveland: 2013 and 2014 Shishaldin:

6 POTENTIAL VOLCANIC HAZARD RELATED USES OF EARTHSCOPE SEISMIC AND INFRASOUND DATA Recent Eruptions Pavlof: 2013 and 2014 Veniaminof: 2013 Cleveland: 2013 and 2014 Shishaldin:

7 POTENTIAL VOLCANIC HAZARD RELATED USES OF EARTHSCOPE SEISMIC AND INFRASOUND DATA Recent Eruptions Pavlof: 2013 and 2014 Veniaminof: 2013 Cleveland: 2013 and 2014 Shishaldin:

8 ALASKA: AVO AND AEC NETWORKS Existing seismic networks AVO: ~220 seismic stations Primarily on AK Peninsula and Aleutian Islands Alaska Earthquake Center (AEC): ~125 seismic stations Primarily in southern and interior AK 13 infrasound sites by UAF-GI and AVO 8

9 ALASKA: 2014 Transportable Array 25 stations added or upgrade Majority in interior AK, Kenai Peninsula 9

10 ALASKA: 2015 Transportable Array 82 stations to be added or upgraded New stations to be added near active, hazardous Cook Inlet volcanoes 10

11 ALASKA: 2016 Transportable Array 98 stations to be added or upgraded Many in northern AK and Canada New or upgraded stations in AK Peninsula and Aleutians 11

12 ALASKA: 2017 Transportable Array 91 stations to be added or upgraded New or upgraded stations in western AK and northern Yukon 12

13 RECENT ADVANCES: LARGE-N SEISMIC imush Univ Washington, Rice, Columbia Univ, Oregon State, ETH-Zurich, USGS Goal: image and interpret the crust and upper mantle with Large-N network MT, active and passive source seismic integrated with geochemical and petrological data Funded via Earthscope and GeoPRISMS, with USGS and Forest Service assistance VolcanoSRI Georgia State, Michigan State, UNC Goal: large-scale sensor network of low-cost stations that computes real-time, full-scale, 3-D fluid dynamics of the volcano conduit system 4D Volcano Tomography in a Large-Scale Sensor Network Funded via NSF CDI imush.org 13

14 CURRENT VOLCANO SEISMIC PROJECTS IN ALASKA Unalaska and Akutan UC Riverside, University of Wisconsin-Madison Goal: Tectonic and volcanic seismicity, as well as image subsurface 4 hybrid mini seismic arrays and 6 stand-alone seismic stations on Unalaska and Akutan Islands Funded via Earthscope, collaboration with AVO Image courtesy AVO Unimak-Cleveland Carnegie Institution of Washington, Columbia University Goal: Analyze volatile content of magmas at a number of depths Combined Geochemical and Geophysical study Geophysics focused on the active Cleveland Volcano Funded via GeoPRISMS, collaboration with AVO NASA Earth Observatory image by Jeff Williams Okmok UCSD, University of Wisconsin-Madison Goal: Seismic and electromagnetic imaging of magma plumbing from slab to surface 13 campaign broadband stations, deployed for 1 year 62 land-based MT sites, 300 km line of marine MT stations in a 2D arc-normal line from the trench into the Bering Sea Funded via GeoPRISMS, collaboration with AVO/USGS 14 Figure courtesy Matt Haney

15 SEISMIC TOMOGRAPHY Syracuse et al. [2015]: joint inversion using local body waves and surface wave dispersion curves from ambient noise at Makushin and Akutan Volcanoes Complex structure with low V p anomaly at 7 km depth and high V p anomaly leading to surface 15

16 OKMOK VOLCANIC TREMOR Tremor back-projection: Spectral whitening, time shift, and compute stack power for candidate source locations At Okmok, virtually no path effects in the Hz band [Haney, 2010] Time shifting based on a homogeneous surface wave velocity model of 2.7 km/s [Masterlark et al., 2010] 16 [Haney, 2014]

17 OKMOK VOLCANIC TREMOR Caldera Wall 1-2 hours prior to tremor escalation Cone D Lake First demonstration of backprojection for tracking changing volcanic tremor Typical tremor location 0-1 hours prior to tremor escalation NORTH Apparent Tremor Movement Waveform inversion yielded a shallow depth for tremor close to back-projection location Array deconvolution needed to resolve km-scale changes in tremor location Tremor movement toward caldera wall [Haney, 2014] Tremor imaging revealed 2 August escalation due to a shift toward intracaldera lake 17

18 RECENT ADVANCES: ACOUSTIC Sakurajima Volcano, Japan Workshop held by IAVCEI Volcano Acoustics Commission at Sakurajima Volcano, Japan Infrasound data uploaded to IRIS- DMC as benchmark dataset for the acoustic community to use in education, training, and research. Focus Section in Seismological Research Letters Infrasound data sped up 40x 18

19 SAKURAJIMA VOLCANO: DEPLOYMENT AND TOPOGRAPHY a) b) 500 ARI Sensors deployed at various angles and distances to vent Topographic obstructions between vent and multiple sensors Elevation [m] Elevation [m] Elevation [m] Elevation [m] Elevation [m] Significant waveform variability > Propagation must be considered before the source can be evaluated-even locally! [e.g. Matoza et al., 2009; Lacanna and Ripepe, 2012]; HAR KOM KUR SVO Distance [m] Pressure [Pa] ARI 2311 m, 186 o HAR 3390 m, 299 o KOM 4481 m, 26 o KUR 3420 m, 81 o SVO 6221 m, 281 o 11:02:00 11:02:05 11:02:10 11:02:15 11:02:20 21 Jul UTC Time [Fee et al., 2014]

20 SAKURAJIMA MODELING Finite-Difference Time-Domain Modeling 3-D GPU-accelerated, high-resolution DEM Anisotropic radiation due to topography Simple source for synthetics suggests waveform complexity from topography [Kim and Lees, 2014] 20 [Kim et al., in press]

21 SAKURAJIMA WAVEFORM INVERSION Excellent waveform fit to observations Monopole source time history (volume flux) 3-D Green's function: smoothly decreasing Half-space Green's function: oscillatory curve First acoustic inversion with computed, 3-D Green s functions Volume/mass flux critical parameter for hazard mitigation 21 [Kim et al., in press]

22 LOCAL AND REMOTE INFRASOUND COMPARISON Unique opportunity to compare local (12 km) and remote (547 km) data and examine long-range propagation High waveform similarity between local (red) and remote (black) stations Principal infrasound waveform features apparent at 547 km (IS53) for most events 22 [Fee et al., 2013]

23 PROPAGATION MODELING AND CROSS-CORRELATION Propagation: Deep atmospheric waveguide between ~40-60 km likely responsible for high waveform similarity Ray tracing predicts a single ground reflection between source and receiver Winds Sound Speed Sound Propagation [Fee et al., 2013] Compute cross-correlation between local and remote data Hilbert transform predicted from ray theory (90 phase shift) improves cross-correlation to 0.89 Remote infrasound can provide good representation of local infrasound 23 [Fee et al., 2013]

24 GLOBAL CATALOGING OF EXPLOSIVE VOLCANISM Project led by Robin Matoza (UCSB) Global association and location: brute force grid-search cross-bearings approach e.g., +/- latitud longitud 24

25 GLOBAL CATALOGING OF EXPLOSIVE VOLCANISM Association and location: brute force grid-search cross-bearings approach Example: Sarychev Peak, 2009 [Matoza et al., 2011] 25

26 SEISMOACOUSTIC STUDIES: CLEVELAND VOLCANO, AK One of the most active and remote volcanoes in the Aleutian arc Mostly small, ash-producing eruptions (<25,000 ), but occasionally >33,000 No real-time, local, seismic network due to logistical challenges (closest seismic station is 75 km) Primarily monitored using remote sensing Ground-coupled airwaves apparent on seismic network Not coherent across network, thus cross-correlation techniques fail OK AKS 26

27 CLEVELAND VOLCANO - DETECT AND NOTIFY Dillingham km Automated detections send alerts to AVO personnel Infrasound From: David Fee dfee@gi.alaska.edu Subject: Cleveland Volcano Dillingham Infrasound Detection Alert: 13-Apr Apr UTC Date: April 13, :08:14 AM PDT To: David Fee <dfee@gi.alaska.edu>, volcanodoctor@gmail.com, Silvio De Angelis <silvio.deange@gmail.com>, @txt.att.net, @txt.att.net, @txt.att.net, Colin Rowell <rowell.colinr@gmail.com> Cleveland Infrasound Detection Alert Dillingham Infrasound Array, 992 km from source Dillingham Detection Time: 13-Apr :54:27 UTC Approx. Origin Time: 13-Apr :02:47 UTC Max Pressure Amplitude: Pa Max Fisher Ratio: 237 Wave Velocity Back-Azimuth [De Angelis et al., 2012] Dec 2011 Aug 2012 Detections: ~7/20 in satellite imagery 19/20 events with infrasound 27

28 CO-LOCATED SEISMIC AND ACOUSTIC SENSORS Seismic-acoustic cross-correlation [Ichihara et al., 2012] and coherence [Matoza and Fee, 2014] acoustic 8 March 2005, Mount St. Helens seismic ~5 m Filtered Waveforms Utilize co-located seismic and acoustic sensors to detect: 1) acoustic signals without an array 2) ground-coupled energy on seismometers Acoustic spectrogram Seismic spectrogram 5-10 Hz cross-correlation Coherence spectrogram Phase spectrogram Infrasound array processing 28 [Matoza and Fee, 2014]

29 EXAMPLE USE OF TA: CHELYABINSK METEOR TOLK (USArray TA station) in Northern Alaska Distance ~6000 km Acoustic-seismic coherence analysis Narrowband 2-4 Hz coherence/coupling acoustic seismic 29

30 EXAMPLE USE OF TA: GROUND-COUPLED AIRWAVE DETECTION AND LOCATION 7-20 Hz waveforms, C=0.13 Envelope (smoothed), C=0.49 (0.76) Pavlof: acoustic waves from explosions commonly recorded on seismometers Time Difference of Arrival: Station-Pair Double Difference and srcloc Hundreds of events located on SE flank, consistent with vent location 30

31 EXAMPLE USE OF TA: REVERSE TIME MIGRATION Acoustic waves recorded on seismic and infrasound sensors of sparse network Waveforms not coherent between stations-use amplitude envelope [Walker et al., 2010] Reverse time migration (backprojection) of sparse network data both seismic and acoustic Provides relatively high resolution location Applicable to volcanic eruptions 31 [Walker et al., 2010]

32 EXAMPLE USE OF TA: REGIONAL ERUPTION TREMOR Remote, catastrophic eruption of Kasatochi Volcano, Alaska in 2008 Prejean and Brodsky [2009] related far-field surface waves to mass eruption rate/plume height 32

33 CONCLUSIONS AND FUTURE WORK Opportunity to use existing networks and Earthscope data to monitor and study volcanic eruptions in Alaska - Detect, locate, image, characterize, and quantify volcanic source - Discriminate between different events *Relatively sparse network not always near volcanoes *Focused deployments for imaging, tracking tremor, etc Utilize co-located seismic and acoustic sensors to detect: - Acoustic signals without an array - Ground-coupled energy on seismometers Stations near volcanoes will improve eq detection and location Integrate with PBO and geologic data 33