The Basin Report

Quakes Still Shake Mentone

Mentone, TX – Yet another tremor was felt near the West Texas towns of Mentone and Orla this morning.  It has been a week of vibrations for the area, this time the earthquake measured 3.6 magnitude.  It is the eighth in four days. 

The U.S. Geological Service reported a 5.0-magnitude quake on Thursday with an epicenter about 27 miles west of Mentone, Texas, 3 miles below the surface, at 9:16 a.m. A total of five earthquake events were recorded near Mentone that day. The 5.0 quake is the third strongest in the state’s history.

Another four earthquakes struck on Friday for a total of nine tremors over a two-day timeframe. The strongest ripple measured 3.8 magnitude and took place about 25 miles west of Mentone and 35 miles northwest of Pecos. Just in the last week, there have been 11 earthquakes near Mentone. The Thursday rumbling was felt as far as Midland to the east and McCamey to the south.

Date and strongest quake:

  • March 28 – 3.6 magnitude
  • March 27 – 3.8 magnitude
  • March 26 – 5.0 magnitude
  • March 25 – 3.2 magnitude
  • March 21 – 3.0 magnitude
  • March 20 – 2.6 magnitude
  • March 19 – 2.8 magnitude

Earthquakes are caused by tectonic movements in the earth’s crust. The shifts are mainly caused when tectonic plates collide, one rides over the other, causing mountain building, earthquakes, and volcanoes. The boundaries between moving plates form the largest fault surfaces on Earth. When they stick, relative motion between the plates leads to increasing stress. This continues until the stress rises and breaks, suddenly allowing sliding over the locked portion of the fault, releasing the stored energy as shock waves.

The earthquakes are caused by the vibrations set up in the earth’s crust which spread outwards in all directions from the source of disturbance. Some of the earthquakes are artificial, while others are natural. Causes of the earthquakes fall into the following broad categories:

  1. Volcanic activities
  2. Folding and faulting
  3. Plate tectonics
  4. Human interference with nature factors

Volcanic activities:
Volcanic explosions are certainly the most common cause of earthquakes in the neighborhood of active volcanoes. Such earthquakes are, therefore, known as volcanic earthquakes. This type of earthquake is caused either under the influence of the increasing pressure of volcanic gases or the subterranean movement of molten lava trying to come up on the earth’s surface. Such earthquakes are common in the area near the volcanoes. They may occur before the volcanoes actually erupt which are, in fact, due to the intrusion of dikes and other movement of lava.

Folding and Faulting:
A fault is defined as a fracture plane along which the rocks have been displaced. There are vertical as well as horizontal displacements. Earthquakes are caused due to sudden movements of rocks along faults. Such earthquakes are called tectonic earthquakes. Remember that the horizontal as well as vertical movements of rocks result from the operation of endogenetic forces beneath the earth’s surface. The fracture of the rock causing a tectonic earthquake is due to elastic strains, which are greater than the strength of the rock can withstand produced by the relative displacement of nearby portions of the earth’s crust. The most destructive Californian earthquake of 1906 was caused by the movement of rocks along the great San Andreas Fault.

Plate Tectonics:
The surface of the earth consists of 15 plates comprising the rigid upper mantle, and the oceanic and continental crust. Out of the total number of plates, 6 are major plates and 9 are minor plates. These plates are always moving. Now, it is an established fact that practically all the tectonic, seismic and volcanic activities take place at the plate margins. Despite the fact that most of the earthquakes occur along the moving plate boundaries, the continental platforms, contrary to general expectations, are also shaken by a few shallow focus earthquakes.

Human interference with nature factors:
Sometimes human interference with nature causes artificial earthquakes. The underground testing of H-bombs produces shock waves through overlying rocks which results in an artificial earthquake. Such earthquakes can be compared with a shallow volcanic earthquake. Blasting of rocks by dynamites for the construction of roads in mountainous regions, deep underground mining for the extraction of minerals, blasting for the construction of dams and reservoirs and similar other human activities may also cause mild tremors. However, all the earthquakes which are caused by human activities are not as terrifying and disastrous as the tectonic earthquakes. All of these earthquakes can be placed in the category of shallow ones.

 

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