Magnitude 5.2 - = ILLINOIS

Magnitude 5.2 - ILLINOIS

2008 April 18 09:37:00 UTC

Versi=F3n=20 en Espa=F1ol

Details
Summary
Maps
Scientific=20 & Technical

Where = can I=20 find...?

Earthquake Details

Magni= tude 5.2

Date-Time<= /A>

Friday, April 18, 2008 at 09:37:00 UTC
Friday, April 18, 2008 at 04:37:00 AM at epicenter=20
Time of Earthquake in other Time = Zones

Locati= on 38.450=B0N, 87.890=B0W

Depth= 11.6 km (7.2 miles) set by location program

Region ILLINOIS

Dista= nces

7 km (5 miles) NNE (13=B0) from Bellmont, = IL
9 km (6 miles) E (88=B0) from Bone Gap, IL
11 km (7 miles) N (350=B0) from Keensburg, = IL
60 km (38 miles) NNW (331=B0) from Evansville, = IN
206 km (128 miles) E (95=B0) from St. Louis,=20 MO

Loc= ation=20 Uncertainty Error estimate not available

Para= meters NST=3D111, Nph=3D111, Dmin=3D36.4 km, Rmss=3D0 sec, Gp=3D = 61=B0,
M-type=3Dmoment=20 magnitude (Mw), Version=3DA

Source

Center for Earthquake Research and Information, Memphis, = Tennessee,=20 USA

Event=20 ID us2008qza6

This event has been reviewed by a seismologist.=20
Did=20 you feel it? Report shaking and damage at your location. = You can=20 also view a map displaying accumulated data from your report and = others.=20

Earthquake Summary

The following is a release by the United States Geological Survey, = National=20 Earthquake Information Center: An earthquake occurred 35 km (20 miles) = SW of=20 Vincennes, Indiana and 205 km (125 miles) SW of INDIANAPOLIS, Indiana at = 3:36 AM=20 MDT, Apr 18, 2008 (4:36 AM CDT in Illinois). The magnitude and location = may be=20 revised when additional data and further analysis results are available. =

Felt Reports

Reports of minor structural damage in West Salem, Illinois and = Louisville,=20 Kentucky. Felt over a wide area of the central United States with felt = reports=20 as far west as Kansas, as far north as the Upper Peninsula of Michigan = and as=20 far south as Georgia.=20

Tectonic Summary

EARTHQUAKES IN THE ILLINOIS BASIN - OZARK DOME REGION
=20 This large region borders the much more seismically active New Madrid = seismic=20 zone on the seismic zone's north and west. The Illinois basin - Ozark = dome=20 region covers parts of Indiana, Kentucky, Illinois, Missouri, and = Arkansas and=20 stretches from Indianapolis and St. Louis to Memphis. Moderately = frequent=20 earthquakes occur at irregular intervals throughout the region. The = largest=20 historical earthquake in the region (magnitude 5.4) damaged southern = Illinois in=20 1968. Moderately damaging earthquakes strike somewhere in the region = each decade=20 or two, and smaller earthquakes are felt about once or twice a year. In=20 addition, geologists have found evidence of eight or more prehistoric=20 earthquakes over the last 25,000 years that were much larger than any = observed=20 historically in the region.

Earthquakes in the central and eastern U.S., although less frequent = than in=20 the western U.S., are typically felt over a much broader region. East of = the=20 Rockies, an earthquake can be felt over an area as much as ten times = larger than=20 a similar magnitude earthquake on the west coast. A magnitude 4.0 = eastern U.S.=20 earthquake typically can be felt at many places as far as 100 km (60 mi) = from=20 where it occurred, and it infrequently causes damage near its source. A=20 magnitude 5.5 eastern U.S. earthquake usually can be felt as far as 500 = km (300=20 mi) from where it occurred, and sometimes causes damage as far away as = 40 km (25=20 mi).

FAULTS
Earthquakes everywhere occur on faults within = bedrock,=20 usually miles deep. Most bedrock in the Illinois basin =96 Ozark dome = region was=20 formed as several generations of mountains rose and were eroded down = again over=20 the last billion or so years.

At well-studied plate boundaries like the San Andreas fault system in = California, often scientists can determine the name of the specific = fault that=20 is responsible for an earthquake. In contrast, east of the Rocky = Mountains this=20 is rarely the case. The Illinois basin - Ozark dome region is far from = the=20 nearest plate boundaries, which are in the center of the Atlantic Ocean, = in the=20 Caribbean Sea, and in the Gulf of California. The region is laced with = known=20 faults but numerous smaller or deeply buried faults remain undetected. = Even the=20 known faults are poorly located at earthquake depths. Accordingly, few=20 earthquakes in the region can be linked to named faults. It is difficult = to=20 determine if a known fault is still active and could slip and cause an=20 earthquake. As in most other areas east of the Rockies, the best guide = to=20 earthquake hazards in the Illinois basin =96 Ozark dome region is the = earthquakes=20 themselves.

Earthquake=20 Information for Illinois

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Scientific & Technical Information

USGS/SLU=20 Regional Moment Tensor Solution=20
Phase=20 Data=20
Seismic=20 Record Section=20
Theoretical=20 P-Wave Travel Times

Preliminary Earthquake Report=20
U.S. = Geological=20 Survey, National Earthquake Information Center:
World Data = Center for=20 Seismology, Denver

Magni= tude	5.2
Date-Time<= /A>	Friday, April 18, 2008 at 09:37:00 UTC Friday, April 18, 2008 at 04:37:00 AM at epicenter=20 Time of Earthquake in other Time = Zones
Locati= on	38.450=B0N, 87.890=B0W
Depth=	11.6 km (7.2 miles) set by location program
Region	ILLINOIS
Dista= nces	7 km (5 miles) NNE (13=B0) from Bellmont, = IL 9 km (6 miles) E (88=B0) from Bone Gap, IL 11 km (7 miles) N (350=B0) from Keensburg, = IL 60 km (38 miles) NNW (331=B0) from Evansville, = IN 206 km (128 miles) E (95=B0) from St. Louis,=20 MO
Loc= ation=20 Uncertainty	Error estimate not available
Para= meters	NST=3D111, Nph=3D111, Dmin=3D36.4 km, Rmss=3D0 sec, Gp=3D = 61=B0, M-type=3Dmoment=20 magnitude (Mw), Version=3DA
Source	Center for Earthquake Research and Information, Memphis, = Tennessee,=20 USA
Event=20 ID	us2008qza6