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Glacial Hazard MonitoringWith Seismology
Fabian Walter2009 – Dr. sc. ETH Zürich2004 – MSc University of Colorado, USA2002 – BSc Brigham Young University, USA
Host: Laboratory of Hydraulics, Hydrology and Glaciology VAWETH Zürich
(at work)
Can we predictdestructiveglacier failure?
Raymond et al. (2003)
Allalingletscher, VS (1965)Unteraargletscher, BE
Weisshorn (4505 m), VS
“Hanging Glaciers”Frozen to bed
Steep glacier tongue• Sliding bed• Subglacial hydraulics
Raymond et al. (2003)
Gornersee,VS
Rock Glacier
Ice dam failure
1.2 km
Early Warning
Monitoring limitationsSurface targeted, only
“See” into the glacier• Fracture state• Basal drainage Seismic noise
measured in situ
Hanging Glaciers: Natural Frequency
Stiffness K• Material quality• Structural damage• Monitoring
collegevibe.com
Milikan Library, California
Chamousset Rock Column, France(Levy et al., 2010; Bottelin et al., 2013)
Hanging Glaciers Break-off• Resonance peak monitoring• Early warning sign• Volume estimate
Resonance Peaks• Frequency decay
prior to failure• Flexure mode
Directional Fourier Transform
Frequency (Hz)
Monitoring of Ice Dam Fractures Rock Glacier
Fracture state seismic velocities
Seismic noise monitoring• “Virtual hammer blows”:
No hammer needed!• Idea: ice dam monitoringHammer blow Force impulse
Seismic Noise Interferometry
Cross-correlation
Walter et al., subm
itted to G
JI0
Steep Glacier Tongues: Seismic Water Tremor
Roger Braithwaite, U Manchester
15 hours
Freq
uenc
y (H
z)
5
10
15
Wat
erPr
essu
re
Röös
li et
al.
(201
4), W
alte
r et a
l. (s
ubm
itted
)
Matched filter processing
Source: USGS
Can Distant Earthquakes TriggerGlacier Failure?
Triggered Glacier Failure?• 2005 Weisshorn break-off only three
days after 9th largest earthquake since 1990 (M8.6 in Indonesia)
• Induced crevasse opening in Antarctica (Peng et al. (2014) in ngeo)
• Glaciers at tipping point?
Landslide in Alaska Range afterM7.9 2002 Denali Fault earthquake
Search digital seismic records for earthquake-induced fractures
Digital seismic records at host institute
Implementation
23 cm
Geopebble (Penn State)
FREEW
IRELESS
Instrument installation• Hanging glacier• Steep glacier tongue• Ice dam
80 cm
Conventional glacier installation
Implementation
2 PhD Students Enough data, fieldwork, subprojects for master’s students
…
1 field engineerTasks1. Tool translation to glaciers2. Data analysis3. Instrument installation
Host Institute: Laboratory of Hydraulics, Hydrology and Glaciology VAW
(ETH Zurich)
Seismology
Glaciology Natural
Hazards
Seismic Noise• U Grenoble• UC San Diego• Stanford• USGS
VAW• Since 1970’s• Field experience
Earthquake Triggering• UC San Diego• Georgia Tech
Fieldwork, instruments• U Grenoble• Penn State
ETH-Internal Collaboration• Swiss Seismological Service• Geophysical Institute
Career Goal: Faculty Position
Teaching: Physics of GlaciersGlaciology Natu
ral
Hazards
Seismology
Fieldwork
Stability
Hydraulics
DamageMechanics
GPS
Photogrammetry
Radarinterferometry
Early warningsystems
Engineeringseismology
Noise interferometry
SensorinstallationFinite element
modeling Data handling
Thank you foryour attention!
Weisshorn: Continuous Spectrograms
Glacier Seismology
Glacier Seismology
Podo
lski
y an
d W
alte
r, in
pre
p.
Career Outlook in Switzerland
GLACIER SEISMOLOGYNATURAL HAZARDS
ETH Zurich:Assistant professor in engineering glaciology
Seismic detection of debris flow/landslide/snow avalanche detection and early warningSwiss Federal Institute for Forest, Snow and Landscape Research WSL:
SLF Uni Berne: Institute of Geological Sciences
Lausanne: Institut de Géographie et Durabilité
Steep Glacier Tongues: “Active” Phases
Röthlisberger and Kasser (1978)
Efficient subglacialdrainage: Melt-suppressed sliding
Inefficient subglacialdrainage: Melt-enhanced sliding
Digital Seismic Records at ETH (since 1997)
Alpine Glacier Seismology• Collaboration VAW- Swiss Seismological Service• Altogether over 3 years of continuous
seismic records
Can Earthquakes Cause Glacier Failure?
Peng et al. (2014)Nature Geoscience
Dynamic FracturingSearch glacier seismic records for earthquake-triggered icequakes
Crevassing events triggered by earthquake surface waves
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