Mammoth Lakes Region: Aftershocks continued to dominate the region following the Hilton Creek M5.1 earthquake on June 8. The intensity of activity was much reduced this week, as only one of the 204 temblors registered in the M3 range.
Pulses and pauses of seismicity occurred through the week yet the daily totals remained at the 20-40 eq/day level. Peak activity occurred on June 29 with 41 eq/day and the fewest number happened the previous day with 21 eq/day. The strongest aftershock measured M2.9 and occurred the morning of July 2.
The largest earthquake was not an Hilton Creek aftershock. The M3.0 temblor occurred June 28 in the Sierra Nevada Mountains south of Mammoth Lakes, near the Silver Divide. It was centered in the same location as four M3's recorded there last week.
Activity in the Long Valley caldera remained relaxed. The only significant action was a cluster of M1's near the Mammoth Airfield (Largest: M1.7).
Regional Activity: On July 1st, at 8:39 p.m., a M4.9 earthquake struck the CA/NV border region in northern Death Valley National Monument, near Scottys Castle.

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The USGS Volcanic Unrest Status is currently GREEN indicating weak to moderate unrest, posing no immediate risk. (more)

For more information on the Long Valley caldera and other volcanoes around the world, please see the following web sites:

Sources: USGS, University of California, Berkeley, Geophysics Laboratory; personal communications.


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