Hazard Notification System (HANS) for Volcanoes


U.S. Geological Survey
Saturday, June 5, 2021, 9:38 PM PDT (Sunday, June 6, 2021, 04:38 UTC)

45°22'26" N 121°41'42" W, Summit Elevation 11240 ft (3426 m)
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREEN

At 20:51 PDT on June 5 (0351 UTC on June 6) a M 3.9 earthquake occurred ~4 km south of the summit of Mount Hood at a depth of 4.3 km below sea level that was felt in the vicinity around Mount Hood. It was preceded by several earthquakes in the hour prior to the M 3.9, and tens of aftershocks have occurred so far with event rates declining in a manner typical of mainshock-aftershock sequences. The mainshock characteristics and location are consistent with past swarms in the Mount Hood area, including a M 4.5 on June 29, 2002, that was located ~1 mile east of the M 3.9. Aftershocks will likely continue for hours or days, some of which may be felt. At this time seismologists at the Cascades Volcano Observatory and Pacific Northwest Seismic Network do not believe that this swarm signifies a change in volcanic hazard at Mount Hood, but will continue to monitor the swarm and will issue further updates as the situation warrants.

The U.S. Geological Survey and Pacific Northwest Seismic Network (PNSN) continue to monitor these volcanoes closely and will issue additional updates and changes in alert level as warranted.

For images, graphics, and general information on Cascade Range volcanoes: https://www.usgs.gov/observatories/cascades-volcano-observatory
For seismic information on Oregon and Washington volcanoes: http://www.pnsn.org/volcanoes
For information on USGS volcano alert levels and notifications: https://www.usgs.gov/natural-hazards/volcano-hazards/notifications