First earthquakes recorded at Crater Lake by new monitoring network.

Three small Volcano-Tectonic (VT) earthquakes were detected at Crater Lake on October 25, 2013, the first to have been recorded since the installation of a small seismic and geodetic network at Crater Lake was completed by CVO in 2011.

The network consists of just three seismic stations, making earthquake locations difficult to determine unless events are large enough to be recorded on stations outside of Crater Lake National Park. The October 25 events were too small to be recorded outside Crater Lake (the largest was a M ~0.8), and so locations cannot be determined. We infer based on how the events were recorded that the events may have been located near the northwestern corner of the crater rim at a depth of 5-10 km.

Prior to these events, the most recent earthquakes to have been recorded within Crater Lake National Park were three events with magnitudes of 2.3, 2.6, and 2.4 that occurred near Rim Village within 20 minutes of each other on the afternoon of December 29, 1994. The largest two events were reportedly felt by people within the Park. The 1994 events were inferred in a 1997 USGS Crater Lake Hazards report to have occurred along a system of regional normal faults.