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dc.contributor.author
Häusler, Mauro
dc.contributor.author
Michel, Clotaire
dc.contributor.author
Burjánek, Jan
dc.contributor.author
Fäh, Donat
dc.date.accessioned
2020-02-04T08:01:36Z
dc.date.available
2020-01-15T21:17:20Z
dc.date.available
2020-01-27T13:25:50Z
dc.date.available
2020-02-04T08:01:36Z
dc.date.issued
2019
dc.identifier.uri
http://hdl.handle.net/20.500.11850/390894
dc.description.abstract
Coseismic landslides and rockfalls are among the most devastating secondary effects of earthquakes. In Switzerland, a country of moderate seismicity, such effects occured, for example, following the 1946 Mw 5.8 Sierre earthquake at Rawilhorn. Combining geospatial susceptibility proxies, such as topography, with models for peak ground acceleration allows for estimating the likelihood of earthquake-induced mass movements on a regional scale (Cauzzi et al., 2018). However, to evaluate the coseismic landslide hazard on a specific slope, detailed investigations on site are required. Therefore, it is of crucial importance to understand the dynamic response of a slope and its dynamic behavior during strong ground shaking. Describing the dynamic response of rock slopes can be achieved by measuring ambient seismic vibrations. It is generally observed that the seismic wavefield polarizes perpendicular to open fractures and that unstable slopes exhibit strong wavefield amplifications. Kleinbrod et al. (2019) established a classification scheme for ambient seismic recordings on rock slope instabilities with two end members: depth-controlled and volume-controlled sites. Depth-controlled sites are characterized by the presence of propagating surface waves and a broad ramp of increasing amplification towards higher frequecies. In contrast, volume-controlled sites exhibit normal mode behavior due to standing wave phenomena within compartments clearly separated by well-defined fracture sets. Normal mode analysis is a well established technique in civil engineering to assess the structural integrity and the dynamic response of the object studied. We performed frequency domain decomposition (FDD) modal analysis on ambient vibration data acquired on an unstable rock site with a volume larger than 150'000 m3 near Preonzo, Canton of Ticino, Switzerland (Häusler et al, 2019, see Fig. 1). We show that the high ground motion amplification and the clear polarization pattern identified by FDD compare well to previous studies that are based on site-to-reference spectral ratios and time-frequency polarization analysis (Burjánek et al., 2018). In addition, FDD allows for a better detection of higher modes, which can be used to efficently map dominant fracture sets. This is of special interest on rock slope instabilities where little or no surface expressions of fractures are developed and where geodetic monitoring systems are not installed yet. Enhanced FDD additionaly provides the damping parameters (energy loss) and an improved estimate of the resonance frequency. These parameters are especially relevant for long term monitoring since they are expected to change with increasing damage, either rapidly after strong ground shaking or other external loading or gradually due to progressive degradation of the rock mass over time (e.g. Michel et al., 2011).
en_US
dc.language.iso
en
en_US
dc.publisher
Platform Geosciences, Swiss Academy of Science (SCNAT)
en_US
dc.subject
rockfall
en_US
dc.subject
Preonzo
en_US
dc.subject
modal analysis
en_US
dc.subject
Ambient vibration
en_US
dc.subject
landslide monitoring
en_US
dc.title
Fracture Network Imaging on the Preonzo rock slope instability using resonance mode analysis
en_US
dc.type
Other Conference Item
ethz.book.title
Abstract Volume 17th Swiss Geoscience Meeting
en_US
ethz.pages.start
173
en_US
ethz.pages.end
174
en_US
ethz.event
17th Swiss Geoscience Meeting (SGM 2019)
en_US
ethz.event.location
Fribourg, Switzerland
en_US
ethz.event.date
November 22-23, 2019
en_US
ethz.notes
Conference lecture on November 23, 2019.
en_US
ethz.publication.place
Berne
en_US
ethz.publication.status
published
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00003 - Schulleitung und Dienste::00022 - Bereich VP Forschung / Domain VP Research::02818 - Schweiz. Erdbebendienst (SED) / Swiss Seismological Service (SED)
en_US
ethz.leitzahl.certified
ETH Zürich::00002 - ETH Zürich::00003 - Schulleitung und Dienste::00022 - Bereich VP Forschung / Domain VP Research::02818 - Schweiz. Erdbebendienst (SED) / Swiss Seismological Service (SED)
en_US
ethz.relation.cites
10.3929/ethz-b-000356369
ethz.date.deposited
2020-01-15T21:17:33Z
ethz.source
FORM
ethz.eth
yes
en_US
ethz.availability
Metadata only
en_US
ethz.rosetta.installDate
2020-01-27T13:26:02Z
ethz.rosetta.lastUpdated
2020-02-04T08:01:47Z
ethz.rosetta.versionExported
true
ethz.COinS
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