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| Titel |
Seismic and mechanical studies of the artificially triggered rockfall at Mount Néron (French Alps, December 2011) |
| VerfasserIn |
P. Bottelin, D. Jongmans, D. Daudon, A. Mathy, A. Helmstetter, V. Bonilla-Sierra, H. Cadet, D. Amitrano, V. Richefeu, L. Lorier, L. Baillet, P. Villard, F. Donzé |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Sciences ; 14, no. 12 ; Nr. 14, no. 12 (2014-12-02), S.3175-3193 |
| Datensatznummer |
250118796
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| Publikation (Nr.) |
 copernicus.org/nhess-14-3175-2014.pdf |
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| Zusammenfassung |
| The eastern limestone cliff of Mount Néron (French Alps) was the theater
for two medium-size rockfalls between summer and winter 2011. On 14 August
2011, a ~2000 m3 rock compartment detached from the
cliff, fell 100 m below and propagated down the slope. Although most of the
fallen rocks deposited on the upper part of the slope, some blocks of about 15 m in size were stopped by a ditch and an earthen barrier after a run-out of
800 m. An unstable overhanging ~2600 m3 compartment
remained attached to the cliff and was blasted on 13 December 2011. During
this artificially triggered event, 7 blocks reached the same ditch, with
volumes ranging from 0.8 to 12 m3. A semi-permanent seismic array
located about 2.5 km from the site recorded the two events, providing a
unique opportunity to understand and to compare the seismic phases generated
during natural and artificially triggered rockfalls. Both events have signal
duration of ~100 s with comparable maximum amplitudes
recorded at large distances (computed local magnitude of 1.14 and 1.05,
respectively), most of the energy lying below 20 Hz. Remote sensing
techniques (photogrammetry and lidar) were employed before and after the
provoked rockfall, allowing the volume and fracturing to be characterized.
This event was filmed by two video cameras, and the generated ground motions
were recorded using two temporary 3C seismic sensors and three seismic arrays
deployed at the slope toe.
Videos and seismogram processing provided estimates of the propagation
velocity during the successive rockfall phases, which ranges from
12 to 30 m s−1. The main seismic phases were obtained from
combined video and seismic signal analyses. The two most energetic phases
are related to the ground impact of fallen material after free fall, and to
individual rock block impacts into the ditch and the earthen barrier. These
two phases are characterized by similar low-frequency content but show very
different particle motions. The discrete element technique allowed
reproducing the key features of the rockfall dynamics, yielding propagation
velocities compatible with experimental observations. |
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