Showing posts with label New Madrid Seismic Zone. Show all posts
Showing posts with label New Madrid Seismic Zone. Show all posts

Saturday, February 15, 2014

South Carolina - 4.1 Magnitude Earthquake - 12km WNW of Edgefield

Earth Watch Report  -  Earthquakes

Instrumental Intensity

ShakeMap Intensity Image
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M 4.1 - 12km WNW of Edgefield, South Carolina

 2014-02-15 03:23:38 UTC

Earthquake location 33.812°N, 82.063°W

Event Time

  1. 2014-02-15 03:23:38 UTC
  2. 2014-02-14 22:23:38 UTC-05:00 at epicenter
  3. 2014-02-14 21:23:38 UTC-06:00 system time

Location

33.812°N 82.063°W depth=4.8km (3.0mi)

Nearby Cities

  1. 12km (7mi) WNW of Edgefield, South Carolina
  2. 31km (19mi) NNE of Evans, Georgia
  3. 32km (20mi) N of Martinez, Georgia
  4. 35km (22mi) NNW of North Augusta, South Carolina
  5. 97km (60mi) WSW of Columbia, South Carolina
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Tectonic Summary

Earthquakes in the Inland Carolinas Region

Since at least 1776, people living inland in North and South Carolina, and in adjacent parts of Georgia and Tennessee, have felt small earthquakes and suffered damage from infrequent larger ones. The largest earthquake in the area (magnitude 5.1) occurred in 1916. Moderately damaging earthquakes strike the inland Carolinas every few decades, and smaller earthquakes are felt about once each year or two.
Earthquakes in the central and eastern U.S., although less frequent than in the western U.S., are typically felt over a much broader region. East of the Rockies, an earthquake can be felt over an area as much as ten times larger than a similar magnitude earthquake on the west coast. A magnitude 4.0 eastern U.S. earthquake typically can be felt at many places as far as 100 km (60 mi) from where it occurred, and it infrequently causes damage near its source. A magnitude 5.5 eastern U.S. earthquake usually can be felt as far as 500 km (300 mi) from where it occurred, and sometimes causes damage as far away as 40 km (25 mi).

Faults

Earthquakes everywhere occur on faults within bedrock, usually miles deep. Most bedrock beneath the inland Carolinas was assembled as continents collided to form a supercontinent about 500-300 million years ago, raising the Appalachian Mountains. Most of the rest of the bedrock formed when the supercontinent rifted apart about 200 million years ago to form what are now the northeastern U.S., the Atlantic Ocean, and Europe.
At well-studied plate boundaries like the San Andreas fault system in California, often scientists can determine the name of the specific fault that is responsible for an earthquake. In contrast, east of the Rocky Mountains this is rarely the case. The inland Carolinas region is far from the nearest plate boundaries, which are in the center of the Atlantic Ocean and in the Caribbean Sea. The region is laced with known faults but numerous smaller or deeply buried faults remain undetected. Even the known faults are poorly located at earthquake depths. Accordingly, few, if any, earthquakes in the inland Carolinas can be linked to named faults. It is difficult to determine if a known fault is still active and could slip and cause an earthquake. As in most other areas east of the Rockies, the best guide to earthquake hazards in the seismic zone is the earthquakes themselves.
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4.3 Quake In South Carolina.

BPEarthWatch BPEarthWatch











Published on Feb 14, 2014
This Quake shook from Alabama to Virginia.
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Sunday, January 26, 2014

New Madrid fault zone could spawn huge quakes in U.S. Midwest, South



Jan. 24, 2014 at 6:44 PM ET
U.S. Geological Survey, file
Undated photo provided by the U.S. Geological Survey shows a landslide trench and ridge east of Reelfoot Lake in Obion County, Tenn., made by the New Madrid earthquakes in the early 1800s.
LOS ANGELES — The New Madrid fault zone in the nation's midsection is active and could spawn future large earthquakes, scientists reported.
It's "not dead yet," said U.S. Geological Survey seismologist Susan Hough, who was part of the study published online Thursday by the journal Science.
Researchers have long debated just how much of a hazard New Madrid (MAD'-rihd) poses. The zone stretches 150 miles, crossing parts of Arkansas, Illinois, Indiana, Kentucky, Mississippi, Missouri and Tennessee.
In 1811 and 1812, it unleashed a trio of powerful jolts — measuring magnitudes 7.5 to 7.7 — that rattled the central Mississippi River valley. Chimneys fell and boats capsized. Farmland sank and turned into swamps. The death toll is unknown, but experts don't believe there were mass casualties because the region was sparsely populated then.
Unlike California's San Andreas and other faults that occur along boundaries of shifting tectonic plates, New Madrid is less understood since it's in the middle of the continent, far from plate boundaries.
Previous studies have suggested that it may be shutting down, based on GPS readings that showed little strain accumulation at the surface. Other research came to the same conclusion by blaming ongoing quake activity on aftershocks from the 1800s, which would essentially relieve strain on the fault.

Read More here


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