Overview
- USGS data show a sequence of 17 earthquakes within about 24 hours near the remote base, led by a magnitude‑4.4 event about 2.5 miles (4 km) deep that drew 111 felt reports and caused no damage.
- USGS research geologist Christopher DuRoss said the depths and waveforms match natural earthquakes in southern Nevada and classified the smaller events as aftershocks rather than a true swarm.
- USGS maps place the cluster in southern Nevada a few to a few dozen miles from Area 51, a region laced with faults where the crust slowly stretches and breaks, which routinely produces tectonic quakes.
- Geophysicist Stefan Burns noted the shallow depth made the signals an unusual case and said there is some ambiguity in the data, while adding the 4.4 mainshock was still most likely natural.
- International monitoring officials and nuclear experts say a covert underground test is unlikely because nuclear blasts leave distinctive seismic signatures and are tracked by the CTBTO’s global sensor network.