Learning more about earthquakes | WNYT.com

Learning more about earthquakes

Learning more about earthquakes

Reid Kisselback
Created: August 09, 2020 05:48 PM

Shortly after 8 A.M. this morning a magnitude 5.1 earthquake struck around two miles southeast of Sparta, N.C.. It was felt as far south as Atlanta and as far north as Baltimore, according to reports made by the public to the United States Geological Survey (USGS). The earthquake was the region’s largest since one of 5.2 magnitude struck in 1916 in the nearby Great Smoky Mountains. Some structural damage to buildings as well as reports of cracked roads and broken water lines were reported.

Imagine the earth’s crust is made of several different puzzle pieces. We call these puzzle pieces tectonic plates, and the edges of the plates are called the plate boundaries. Plate boundaries are made up of many faults, and most of the earthquakes around the world occur along these faults. Since the edges of the plates are rough, they get stuck while the rest of the plate keeps moving. Finally, when the plate has moved far enough, the edges unstick on one of the faults and there is an earthquake. The surface where they slip is called the fault or fault plane. We use the Richter Scale to measure the strength of a earthquake based on a scale from 0-9.

According to the USGS, “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 60 miles 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 300 miles from where it occurred, and sometimes causes damage as far away as 25 miles.”  The reason why this occurs is that on the east coast you have condensed, old rock relatively near the center of the tectonic plate that has not been broken up as much. When an earthquake occurs, the energy is transferred very smoothly and easily over a long distance. Whereas if you are on the West Coast, you have a lot more cracks, breaks, and faults that help to dissipate the energy.  It is not felt as far because it has to travel through a lot of different rock formations and structures that are looser. The earthquake energy is lost in the movement of the crust from one area to another.

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