An earthquake of Ml 4.0 occurred west of Trinidad, Colorado this morning.
The quake was the largest in the region since Sept 23, 1973 when a
Ml 4.2 occurred near today's epicenter. The only other event with
magnitude exceeding Ml 4.0 that has been recorded in the area 37-39N
102-106W (SE Colorado) occurred on October 3, 1966 (Ml 4.6). This is
the third event of Ml>=3 in this region during thte past week.

NEIS is giving the following parameters for today's event which
was likely felt throughout the region:
ML 4.0 2001/09/04 12:45:53 37.15N 104.65W COLORADO
Source: http://wwwneic.cr.usgs.gov/neis/bulletin/bulletin.html

CERI parameters for all three events are:
ML 4.0 2001/09/04 07:45:53 37.148N 104.646W West of Trinidad Colorado
ML 3.5 2001/08/28 09:22:00 37.080N 104.655W West of Trinidad Colorado
ML 3.4 2001/08/28 09:16:09 37.089N 104.739W West of Trinidad Colorado
Source: http://folkworm.ceri.memphis.edu/recenteqs/Quakes/quakes0.html

The aftershock forecast from the Pacific Antarctic Ridge event had noted
that an area of the U.S. between 34 and 36 N often became activated following
events in the PAR region. This event lies slightly to the north of this band and lies
101 degrees from the New Zealand earthquake of 21 August (Me 7.2). A swarm
of earthquakes also occurred with the largest Ml 3.2 in the Jackson Lake region
of Wyoming yesterday. These events lie at 101 degrees from the PAR earthquake,
at the shadow zone boundary where far-field triggering is expected.

Jackson Lake WY earthquake list:
http://www.seismo.usbr.gov/quake/Jlsn.txt

• Central U.S. Earthquakes