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 It
was an earthquake 539 miles to our southwest recorded at a magnitude
of 5.6 magnitude and almost 4 miles deep. The epicenter of the
largest quake occurred northwest of Pawnee, Oklahoma at 7:02 a.m.
The quaking in that area actually began on Friday evening with two
smaller quakes in two different directions several miles from
Pawnee. At 8:45 p.m. a quake NW of Pawnee, in Medford, OK,
registered 3.2M at a depth of 5 km. At 9:30 p.m. another quake
occurred to the south of Pawnee in Luther, OK, that measured 3.1M
and reached a depth of 9 km.
The 5.6 M quake epicenter was located eight miles northwest of
Pawnee, which has a population of 2,179.
At the time of this report at 11 a.m. Saturday morning, 10 quakes
are on record for the small region; eight and still counting
continue for the Pawnee site. Some of the stats at Pawnee: 3.4M at
7:16 a.m., 3.6 at 7:58M a.m., and 3.2M at 10:31 a.m.
Distances from the epicenter:
- Masham, Oklahoma, 6.7 km (4.1 mi), WSW, Population: 0
- Ponca City, Oklahoma, 34.1 km (21.2 mi), SSE, Population:
25,387
- Stillwater, Oklahoma, 36.8 km (22.9 mi), NNE, Population:
45,688
- Arkansas City, Kansas,71.0 km (44.1 mi) S, Population:
12,415
- Oklahoma City, Oklahoma, 119.3 km (74.1 mi), NNE,
Population: 579,999
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Regional map
U.S. map showing earthquake locations
According to the USGS, quakes east of the Rockies are felt for
greater distances and are likely to cause greater structural damages
further out than quakes that occur on the west coast.
[Earthquakes east of the Rocky Mountains, although less frequent than in the
West, are typically felt over a much broader region than earthquakes of similar
magnitude in the west. East of the Rockies, an earthquake can be felt over an
area more than ten times larger than a similar magnitude earthquake on the west
coast. It would not be unusual for a magnitude 4.0 earthquake in eastern or
central North America to be felt by a significant percentage of the population
in many communities more than 100 km (60 mi) from its source. A magnitude 5.5
earthquake in eastern or central North America might be felt by much of the
population out to more than 500 km (300 mi) from its source. Earthquakes east of
the Rockies that are centered in populated areas and large enough to cause
damage are, similarly, likely to cause damage out to greater distances than
earthquakes of the same magnitude centered in western North America. - USGS]
[Jan Youngquist]
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