Hi All. There has been a silent quake 20 to 30 miles deep beneath Friday Harbor in the San Juan Islands, according to M. Meghan Miller, a geophysicist at Central Washington and lead author of yesterday's report.

This is also the same area as the most recent M>=4.1 quake that occurred on 09/21/2002

Researchers at Central Washington University in Ellensburg are reporting in the journal Science that they have detected eight of these silent quakes in the past 10 years by monitoring signals received at ground stations from the Global Positioning System, a network of 24 orbiting satellites with instruments that can measure surface ground motions as tiny as a fraction of an inch.

According to Mal Johnston at USGS sequences of near-silent earthquakes were recorded on a network of three borehole strainmeters along 15 km of the San Andreas fault north of San Juan Bautista (SJB), California, in December, 1992 and in April, 1996. Other events were recorded on borehole strainmeters along the Hayward fault in June, 1993, November, 1993, and September, 1994. "Silent" or "Slow" earthquakes resemble ordinary earthquakes in the pattern of strain release but occur over several days with little or no seismic radiation. The SJB events have associated earthquake swarms, an "aftershock" sequence and observable surface rupture (creep) days to weeks later. The first in the SJB sequence started on December 11, 1992, and continued for a week. It eventually ruptured an 8 km long section of the fault to a depth of about 8 km in several subevents, each closely associated with moderate magnitude earthquakes and microseismicity. Take Care…Don in creepy town

• Silent Earthquake