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By SABRINA BATES Special to The Messenger West Tennessee has experienced at least six minor quakes within the last week, but according to the Mid-America USGS Center for Earthquake and Information Education Outreach director, the recent activity is within the normal levels of the Reelfoot fault area. On Monday, Gary Patterson explained that the West Tennes-see region, which rests on what is dubbed the “Reelfoot Fault,” records at least 200 earthquakes every year. “What it means is that these earthquakes are within the normal levels of activity. There is no reason to think that a large-scale event is imminent because of all the recent earthquakes,” Patterson said. While it is not unusual to experience five quakes within a seven-day period for this region, the information can help the United States Geological Society determine trends and patterns in the event of a large-scale disaster. Patterson said while the New Madrid Seismic Zone does not produce larger and more frequent earthquakes, such as California’s fault line, the region impacted by a large scale event would impact a “ridiculously larger area.” “There are even dozens, maybe hundreds of smaller earthquakes that register less than 1 on the Richter scale that we can’t measure because they occur below our instruments,” Patterson said. The earthquakes that are reported trigger at least three different measuring stations within the New Madrid region. Those are the quakes that the USGS is able to catalog for future research. Patterson noted there are at least 140 instruments scattered throughout 11 central states used for earthquake measurements. “These frequent earthquakes are a reminder that the New Madrid Seismic Zone is active and it is prudent to be prepared,” Patterson said. A large-scale event similar to that of 1811-12 that eventually formed Reelfoot Lake would incapacitate West Tennessee by knocking out electricity. Water, non-perishable foods and cash are important to have on hand in the event of a large-magnitude earthquake. A quake which measures 4 on the Richter scale is enough to cause minor structure damage. People will actually “feel” a quake that measures 2.5 on the Richter scale, but smaller quakes that register closer to the Earth’s surface can also be felt. Even with decades of data, there is still no way to predict or even give warning of an imminent earthquake. Patterson did reveal, however, that researchers in California are compiling data in the hopes of providing even a 15- to 20-second lead time for alerts. “Even with only 15 to 20 seconds, we would be able to warn people, hopefully in time to shut off critical gas stations,” Patterson said. “And, there is no doubt that animals can sense something before it happens,” he added. Unfortunately, there is no way to “quantify” what it is they are sensing, according to Patterson. According to the USGS, six small earthquakes were measured in the New Madrid Seismic region within the last week. On Wednesday, a 2.0 magnitude quake was recorded at 8:49 p.m. that day. The quake occurred 3.5 miles below the Earth’s surface and 21 miles southwest of Blytheville, Ark. On Thursday at 11:34 p.m., a smaller quake measuring 1.3 was documented five miles south of Ridgley with a depth of 3.9 miles. The following morning on Friday at 6:02 a.m., a quake with a magnitude of 2.5 was recorded 10 miles southwest of Hornbeak. Its depth was 4.9 miles. Two small quakes were recorded within 40 minutes of one another on Saturday. The first occurred at 8:31 p.m. 11 miles southwest of Hornbeak and measured a 1.2 magnitude. Its depth was documented at 4.6 miles. The second quake that day registered a 1.5 magnitude at 9:05 p.m. It occurred three miles northwest of Dyersburg and 4.8 miles below the Earth’s surface. On Sunday, a 1.9 magnitude earthquake was reported at 5:29 p.m. Its depth measured 5.5 miles and occurred four miles west, northwest of Tiptonville. The American Red Cross offers safety and preparation tips on its Web site at www.redcross.org. According to the organization, in the event of an earthquake, stay clear of windows and interior walls. The Red Cross recommends staying indoors during a quake. Doorways are no stronger than any other part of a structure. During an earthquake, get under a sturdy piece of furniture and hold on. This will provide some protection from falling objects that can injure you during an earthquake. If you are outside, find a clear spot and drop to the ground. Do not move until the shaking stops. For more information, visit www.redcross.org. Published in The Messenger 12.01.09 |
