Thursday, May 17, 2012

East Texas Earthquake History

Update.  May 17th Earthquake was revised to a 4.8!

At 3:12AM this morning the Earth shook to the magnitude of 4.3 on the Richter Scale as the second earthquake to hit East Texas this month gave a rude awaking to many this morning. Although not unheard of, earthquakes across East Texas are very rare. It has been over 30 years since the last earthquake over 3.0 on the Richter scale hit east Texas which occurred in Jacksonville in November of 1981. When we think of earthquakes we normally associate California or any other western state where much of the country’s strongest earthquakes have occurred. But earthquakes occur all over the United States and even here in East Texas. Since 1850 there have now been 11 earthquakes reported in East Texas with a magnitude of 3.0 or greater on the Richter Scale. So let’s take a look at when, where, and why these quakes occurred. The first major earthquake to affect East Texas was probably the great Madrid Fault quake of 1811 in the Boot Heel of Missouri and measured 8.1 on the Richter Scale. This quake caused damage as far away as Boston, MA so I have a hard time believing East Texas did not feel the effects from this quake. However, this first recorded earthquake greater than 3.0 to hit East Texas occurred on January 9th 1891 in Rusk. This quake measured 4.0 on the Richter Scale and reportedly caused significant damage in a few areas. However, there was also a strong tornado that moved across the area that evening and much of the damage reported was probably from weather and not the Earthquake. The next earthquake to affect East Texas was also the strongest recorded in the area, a 4.7 magnitude quake on March 19th 1957 northeast of Diana. A few windows were broken and much of northeast Texas felt this quake. For the next seven years the seismic activity across East Texas was quite until April of 1964 when the most active seismic activity hit East Texas. On April 23rd the first quake struck in the southeastern part of Texas near Hemphill and would be the first of eight earthquakes to hit the area over the next few months. In April there were quakes on the 23rd, 24th, 27th, and 28th, with the one on the 28th measuring 4.4 on the Richter Scale. The quakes between the 23rd and 27th all measured between 3.4 and 3.7 on the Richter Scale. There were two smaller quakes on April 30th and May 7th followed by a 4.2 magnitude quake on June 2nd. The last earthquake in East Texas that year occurred on August 16th and was minor. The next series of earthquakes did not hit East Texas until 1981 when on June 9th a 3.2 magnitude quake hit Center, fairly close to where today’s quake hit. The next quake that year hit on November 6th I Jacksonville registering 3.3 on the Richter Scale. The last two known earthquakes in East Texas to be a magnitude of 3.0 or higher of course have occurred this month, a 3.9 on the 10th and a 4.3 today. Today’s quake has caused some damage in the Timpson area and even one injury but thankfully nothing too extreme. When you look at the fault lines across the country you will notice there are literally hundreds that run northwest to southeast across East Texas. That fault lines are classified here as “Class B” faults meaning there is very little seismic activity. It is also interesting to note that studies have suggested that much of the seismic activity along these faults could have been artificially created due to the extraction of oil. I by no means am an expert on this subject but have taking a few geology and geography classes while studying meteorology and find the subject interesting. All the information above in this article came from doing some research this morning on the USGS website. Based on the information I have learned today I would not be surprised to see one or two more quakes before the fault settles down again. Thankfully major damage rarely occurs from earthquakes under 6.0 here in the United States with our stronger building codes and the type of faults across East Texas have yet to produce that strong of an earthquake.