Magnitude‐based discrimination of man‐made seismic events from naturally occurring earthquakes in Utah, USA

Abstract

We investigate using the difference between local (ML) and coda/duration (MC) magnitude to discriminate man‐made seismic events from naturally occurring tectonic earthquakes in and around Utah. For 6846 well‐located earthquakes in the Utah region, we find that ML‐MC is on average 0.44 magnitude units smaller for mining‐induced seismicity (MIS) than for tectonic seismicity (TS). Our interpretation of this observation is that MIS occurs within near‐surface low‐velocity layers that act as a waveguide and preferentially increase coda duration relative to peak amplitude, while the vast majority of TS occurs beneath the near‐surface waveguide. A second data set of 3723 confirmed or probable explosions in the Utah region also has significantly lower ML‐MC values than TS, likely for the same reason as the MIS. These observations suggest that ML‐MC is useful as a depth indicator and could discriminate small explosions and mining‐induced earthquakes from deeper, naturally occurring earthquakes at local‐to‐regional distances.

Afterslip Enhanced Aftershock Activity During the 2017 Earthquake Sequence Near Sulphur Peak, Idaho

“…Details of the procedures used by UUSS to calculate magnitudes are available in Pechmann et al (2006) for M C and in Pechmann et al (2007) for M L . The two magnitude scales are designed to be seamless, and for earthquakes in the Utah region that occur deeper than 3-4 km, the average M L -M C is near zero (Koper et al, 2016). Breckenridge et al (2003).…”

Current challenges in monitoring, discrimination, and management of induced seismicity related to underground industrial activities: A European perspective

“…A major, obvious difference concerns their shallow hypocentral depth, which may affect other source parameters and signal characterization. For example, Koper et al [] found anomalous deviations among local and coda/duration magnitude for mining‐induced seismicity, with respect to tectonic events and used this parameter to discriminate induced seismicity; this anomaly was interpreted as a consequence of the shallow depth of mining‐induced seismicity, located within near‐surface low‐velocity layers acting as a waveguide for trapped waves, thus increasing the signal duration at the cost of a lower peak amplitude, as sometimes observed at volcanoes. Even a low‐aftershock productivity evidenced, e.g., by Dahm et al [] for an induced earthquake in Germany, in comparison to tectonic earthquake of similar magnitude in the same region, could be finally linked to the shallow source location within different geological units.…”

Imbalanced Seismic Event Discrimination Using Supervised Machine Learning

“…One factor that interferes with the classification is an artificial explosion. Artificial explosions, e.g., quarry blasts, explosive bomb tests, and underground nuclear tests, accompany seismic tremors, and the surface oscillations are similar to earthquakes [ 1 ].…”