Seismo-Watch

More Special Earthquake Reports

June 29, 2002

An earthquake measuring M 4.5 occurred early this morning at Mount Hood, stirring many people from sleep but not causing any damage or injuries.

Seismo-Watch EQ Flash! Alert Bulletins notified subscribers of this earthquake within minutes after it happened. You should subscribe to the service too! It's FREE and Fast! NOW!! Wireless EQ Flash! via pager, cell phone or PDA's! More info.

According to the Pacific Northwest Seismic Network (PNSN), the earthquake registered a magnitude (Ml) 4.5 and occurred at 14:36:04 GMT or 7:36 a.m. PDT, June 29, about 47 miles east-southeast of Portland, 3 miles south of the summit of Mount Hood, and a mile east of the Timberline Lodge, in the upper reaches of Whites Creek. See a Topozone topographic map or a MapQuest street map. See USGS real time earthquake epicenter map for the greater Portland, OR region.

The focal depth was about 6.2 km beneath the surface. This is a typical depth for earthquakes near Mount Hood.

Foreshocks and Aftershocks
The mountain has experienced a few swarms in the past few months, so it was not unexpected to see a small M 1.2 tremor on June 27 and a M 1.1 a minute prior to the main jolt.

A robust aftershocks sequence has followed, consisting of dozens of microseisms, many of which have not been processed at this time but are visible from the waveform strip chart.

Six aftershocks have registered M 2.0 or stronger, including two in the M 3.0 range. The first measured M 3.2 and occurred at 7:41 a.m., just five minutes after the main shock. The second came at 11:50 a.m. and measured M 3.8. See a current list of events In the area.

Felt Reports
The main quake was felt by many people living in the area and some as far away as Portland and The Dallas, and many parts of southern Washington. There have been no reports of items toppling from tables and shelves and no one was injured. See the USGS Community Intensity Report.

Most people near the mountain described the earthquake as one sharp jolt while others further away said it felt like a low rumble.

KGW news in Portland has a very good report here. They reported that people at Timberline Lodge stopped in their steps, but not even a postcard fell from the racks.

Background Information

More will be added shortly. Check the Seismo-Watch PNW Report for recent regional activity. Be sure to check the archive for past reports.

Additional seismic information links:

• Seismo-Watch - links for more Pacific Northwest information
  • Weekly Seismo-Watch Pacific Northwest Earthquake Report
• Pacific Northwest Seismic Network Special Report
• USGS real time earthquake epicenter map for the greater Portland, OR region
• USGS Community Intensity Report

Mainstream media news reports:
Outside news stories will open a new browser window

• Earthquake Shakes Mount Hood Area - AP via Yahoo! News
• Earthquake Rattles Portland Area - kgw.com Portland News