Seismo-Watch Significant Earthquake Report - No. 01-028
Regional Location:

Preliminary Magnitude:

Greenwich Mean Date:
Greenwich Mean Time:
Latitude:
Longitude:
Focal Depth:

PORTOLA, NORTHEASTERN CALIFORNIA

ML 5.5 (NCSN), ML 5.5 (UNRSL), Mw 5.2 UCBSL

01/08/10
20:19:26 (1:19 p.m. local time)
39.828N
120.632W
14.5 km

PORTOLA M5.5 EARTHQUAKE REPORT (Continued, Page 2)

Felt Reports
The temblor was widely felt in the region and as far away as Sacramento, Redding, California and Carson City, Fallon, and Lovelock, Nevada. There are some reports the quake was felt in the San Francisco Bay area and Santa Rosa. Many felt an initial jolt (P-wave) followed by a brief pause then more shaking (S-wave). There have been no reports of any serious damage at this time. People reported windows shaking, pictures knocked askew, and dishware rattling but apparently only a few light items toppled from tables and shelves.

Did you feel this quake? Tell us what you felt. We want to know.

Many people were frightened by the shaking but just as soon as they began to rise to get to cover, the shaking stopped. Most estimated the shaking lasted for a few seconds, perhaps 3-5 seconds, some thought it lasted longer.

Many people in the epicentral reported hearing an explosion-like sound just prior to the shaking. In Reno, several people heard the ground groan with the shaking. Groan-like sounds were also heard in the Tahoe and Sacamento Valley.

Video footage from Reno and Sacramento television stations showed many shops in the Portola and Graeagle areas with no toppled items. Some people interviewed were noticeably disturbed by the quake while others were charged with excitement.

Shaking at Seismo-Watch
The corporate offices of Seismo-Watch distinctly felt the Portola quake. Charles Watson and Forrest Hopson were busy preparing weekly earthquake reports for newspapers when the walls and windows began to vibrate. Both men looked up, quickly saving their work on the computers. There was a brief pause in the shaking and both men called out "Did you feel that?!". Just then the shaking began again this time a little more vigorously but the amplitude and period of the seismic waves were short and rolling, suggesting to the men that the quake was centered as some distance away but not to far and it must have been of "good size". Hanging plants swung slightly, perhaps a few inches from center, and pictures on walls rattled. There was a distinct groan-like noise that accompanied the shaking. Both men were charged with excitement, then the phone began to ring and the local news crews were calling... back to work.

Continued on Page 3

Report update: 11:50 p.m., August 11, 2001

Wednesday, August 22, 2001
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