- Massive landslide at Utah copper mine generates wealth of geophysical data
- Kristine Pankow ; Jeffrey Moore ; J. Hale ; Keith Koper ; Tex Kubacki ; Katherine Whidden ; Michael McCarter
- Year: 2013
- Geophysics ; Landslides ; Slope Stability
- Keywords: Landslide ; geophysical data ; Bingham Canyon ; Utah
- Abstract
- On the evening of 10 April 2013 (MDT) a massive landslide occurred at
the Bingham Canyon copper mine near Salt Lake City, Utah, USA. The
northeastern wall of the 970-m-deep pit collapsed in two distinct
episodes that were each sudden, lasting ~90 seconds, but separated in
time by ~1.5 hours. In total, ~65 million cubic meters of material was
deposited, making the cumulative event likely the largest non-volcanic
landslide to have occurred in North America in modern times.
Fortunately, there were no fatalities or injuries. Because of extensive
geotechnical surveillance, mine operators were aware of the
instability and had previously evacuated the area. The Bingham Canyon
mine is located within a dense regional network of seismometers and
infrasound sensors, making the 10 April landslide one of the best
recorded in history. Seismograms show a complex mixture of short- and
long-period energy that is visible throughout the network (6–400 km).
Local magnitudes (ML) for the two slides, which are based on
the amplitudes of short-period waves, were estimated at 2.5 and 2.4,
while magnitudes based on the duration of seismic energy (md) were much
larger (>3.5). This magnitude discrepancy, and in particular the
relative enhancement of long-period energy, is characteristic of
landslide seismic sources. Interestingly, in the six days following the
landslide, 16 additional seismic events were detected and located in
the mine area. Seismograms for these events have impulsive arrivals
characteristic of tectonic earthquakes. Hence, it appears that in this
case the common geological sequence of events was inverted: Instead of a
large earthquake triggering landslides, it was a landslide that
triggered several small earthquakes.
PDF |
