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 (M L) 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 (m d) were much larger (>3.5). This magnitude discrepancy, and in particular the relative enhancement of longperiod 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.

On 6 August 2007, the Crandall Canyon Mine in central Utah experienced a major collapse that was recorded as an M w 4.1 seismic event. Application of waveform cross-correlation detection techniques to data recorded at permanent seismic stations located within~30 km of the mine has resulted in the discovery of 1494 previously unknown microseismic events related to the collapse. These events occurred between 26 July 2007 and 19 August 2007 and were detected with a magnitude threshold of completeness of 0.0, about 1.6 magnitude units smaller than the threshold associated with conventional techniques. Relative locations for the events were determined using a double-difference approach that incorporated absolute and differential arrival times. Absolute locations were determined using ground-truth reported in mine logbooks. Lineations apparent in the newly detected events have strikes similar to those of known vertical joints in the mine region, which may have played a role in the collapse. Prior to the collapse, seismicity occurred mostly in close proximity to active mining, though several distinct seismogenic hot spots within the mine were also apparent. In the 48 h before the collapse, changes in b value and event locations were observed. The collapse appears to have occurred when the migrating seismicity associated with direct mining activity intersected one of the areas identified as a seismic hot spot. Following the collapse, b values decreased and seismicity clustered farther to the east.