Related Research Articles
An earthquake – also called a quake, tremor, or temblor – is the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they cannot be felt, to those violent enough to propel objects and people into the air, damage critical infrastructure, and wreak destruction across entire cities. The seismic activity of an area is the frequency, type, and size of earthquakes experienced over a particular time. The seismicity at a particular location in the Earth is the average rate of seismic energy release per unit volume.
An intraplate earthquake is an earthquake that occurs in the interior of a tectonic plate, in contrast to an interplate earthquake on the boundary of a tectonic plate. It is also called an intraslab earthquake, especially when occurring in a microplate.
The 1811–1812 New Madrid earthquakes were a series of intense intraplate earthquakes beginning with an initial earthquake of moment magnitude 7.2–8.2 on December 16, 1811, followed by a moment magnitude 7.4 aftershock on the same day. Two additional earthquakes of similar magnitude followed in January and February 1812. They remain the most powerful earthquakes to hit the contiguous United States east of the Rocky Mountains in recorded history. The earthquakes, as well as the seismic zone of their occurrence, were named for the Mississippi River town of New Madrid, then part of the Louisiana Territory and now within the U.S. state of Missouri.
The New Madrid seismic zone (NMSZ), sometimes called the New Madrid fault line, is a major seismic zone and a prolific source of intraplate earthquakes in the Southern and Midwestern United States, stretching to the southwest from New Madrid, Missouri.
The Seattle Fault is a zone of multiple shallow east–west thrust faults that cross the Puget Sound Lowland and through Seattle in the vicinity of Interstate Highway 90. The Seattle Fault was first recognized as a significant seismic hazard in 1992, when a set of reports showed that about 1,100 years ago it was the scene of a major earthquake of about magnitude 7 – an event that entered Native American oral traditions. Extensive research has since shown the Seattle Fault to be part of a regional system of faults.
The 2003 Alabama earthquake took place on April 29 at 3:59 A.M. Central Daylight Time eight miles (13 km) east-northeast of Fort Payne, Alabama. The number of people who felt this quake was exceptionally high as the earthquake could be felt in 11 states across the East Coast and as far north as southern Indiana. The earthquake was strongly felt throughout metropolitan Atlanta. The Georgia Building Authority was called out to inspect the historic Georgia State Capitol in downtown Atlanta and other state-owned buildings but found no problems. However, this is not out of the ordinary as earthquakes east of the Rocky Mountains can be felt several times the area felt on West Coast earthquakes. The earthquake was given a magnitude 4.6 on the moment magnitude scale by the USGS and reports of the duration of the shaking range from 10 seconds to as long as 45 seconds. It is tied with a 1973 earthquake near Knoxville, Tennessee as the strongest earthquake ever to occur in the Eastern Tennessee seismic zone, which is the second most active seismic zone east of the Rocky Mountains, with the New Madrid seismic zone the most active.
The Virginia seismic zones in the U.S. state of Virginia include the Giles County seismic zone and the Central Virginia seismic zone. Earthquakes in the state are irregular and rarely reach over 4.5 in magnitude.
The geology of Alabama is marked by abundant geologic resources and a variety of geologic structures from folded mountains in the north to sandy beaches along the Gulf of Mexico coast. Alabama spans three continental geologic provinces as defined by the United States Geological Survey, the Atlantic Plain, Appalachian Highlands, and Interior Plains. The Geological Survey of Alabama breaks these provinces down into more specific physiographic provinces.
The Ramapo Fault zone is a system of faults between the northern Appalachian Mountains and Piedmont areas to the east. Spanning more than 185 miles (298 km) in New York, New Jersey, and Pennsylvania, it is perhaps the best known fault zone in the Mid-Atlantic region, and some small earthquakes have been known to occur in its vicinity. Recently, public knowledge about the fault has increased, especially after the 1970s, when the fault's proximity to the Indian Point nuclear plant in New York was noted.
The 1916 Irondale earthquake struck in the north-central region of the U.S. state of Alabama on October 18. The strongest earthquake in state history, it registered an estimated Richter scale magnitude of 5.1 and resulted in minor damage. Damage was limited to Shelby and Jefferson counties and reached its maximum severity near the epicenter in the city of Irondale, including cracked windows, fallen chimneys, and dried-up wells. While there were no fatalities, the earthquake spawned widespread panic, prompting alarmed workers to evacuate tall buildings.
The Puget Sound faults under the heavily populated Puget Sound region of Washington state form a regional complex of interrelated seismogenic (earthquake-causing) geologic faults. These include the:
The New York–Alabama Lineament is a magnetic anomaly in the geology of eastern North America running from Alabama to New York. The lineament is defined by discontinuities in aeromagnetic measurements indicating an approximately 220-kilometre (140 mi) displacement of buried geologic structures along this line. The displacement is attributed to the presence of a deeply buried strike-slip fault, possibly dating to the general time of the Grenville orogeny. The lineament was first described in 1978. The fault zone has been associated with the Eastern Tennessee seismic zone.
The 2011 Oklahoma earthquake was a 5.7 magnitude intraplate earthquake which occurred near Prague, Oklahoma on November 5 at 10:53 p.m. CDT in the U.S. state of Oklahoma. The epicenter of the earthquake was in the vicinity of several active wastewater injection wells. According to the United States Geological Survey (USGS), it was the most powerful earthquake ever recorded in Oklahoma until the 2016 Oklahoma earthquake. The previous record was a 5.5 magnitude earthquake that struck near the town of El Reno in 1952. The quake's epicenter was approximately 44 miles (71 km) east-northeast of Oklahoma City, near the town of Sparks and was felt in the neighboring states of Texas, Arkansas, Kansas and Missouri and even as far away as Tennessee and Wisconsin. The quake followed several minor quakes earlier in the day, including a 4.7 magnitude foreshock. The quake had a maximum perceived intensity of VIII (Severe) on the Mercalli intensity scale in the area closest to the epicenter. Numerous aftershocks were detected after the main quake, with a few registering at 4.0 magnitude.
The 1879 Gansu earthquake occurred at about 04:00 local time on 1 July. It had an estimated magnitude of 8.0 on the Ms scale and a maximum perceived intensity of XI (Extreme) on the Mercalli intensity scale. The epicenter was in Wudu District in southern Gansu, close to the border with Sichuan. It caused widespread damage and killed an estimated 22,000 people.
The Oklahoma earthquake swarms are an ongoing series of human activity-induced earthquakes affecting central Oklahoma, southern Kansas, northern Texas since 2009. Beginning in 2009, the frequency of earthquakes in the U.S. state of Oklahoma rapidly increased from an average of fewer than two 3.0+ magnitude earthquakes per year since 1978 to hundreds each year in the 2014–17 period. Thousands of earthquakes have occurred in Oklahoma and surrounding areas in southern Kansas and North Texas since 2009. Scientific studies attribute the rise in earthquakes to the disposal of wastewater produced during oil extraction that has been injected more deeply into the ground.
Meers Fault is a fault in Oklahoma that extends from Kiowa County to Comanche County. It is marked by a 22–26 kilometers (14–16 mi) long conspicuous fault scarp but the fault extends beyond the ends of this scarp. The Meers fault is part of a group of faults that lie between the Anadarko Basin and the Wichita Mountains.
The 2020 Sparta earthquake occurred in North Carolina on August 9 at 08:07 EDT. The epicenter of this relatively uncommon intraplate earthquake was near the small town of Sparta, Alleghany County. The thrust-faulting earthquake had a moment magnitude of 5.1, occurring at a shallow depth of 4.7 miles (7.6 km). Rupture occurred on the previously unmapped Little River Fault. A surface rupture was documented following the earthquake; the first of its kind in the Eastern United States. Shaking was reported in parts of the Midwestern, and Southeastern United States. It was the strongest earthquake recorded in North Carolina in 104 years, the second-strongest in the state's history, and the largest to strike the East Coast since the 2011 Virginia earthquake. The earthquake significantly damaged homes and businesses in Sparta and injured at least one person. The shaking was also felt in other states along the East Coast. A state of emergency was declared in Sparta, and North Carolina granted $24 million in relief fund for repair works.
The 1895 Charleston earthquake, also known as the Halloween earthquake, occurred on October 31, at 05:07 CST near Charleston, Missouri. It had an estimated moment magnitude of 5.8–6.6 and evaluated Modified Mercalli intensity of VIII (Severe). The earthquake caused substantial property damage in the states of Missouri, Illinois, Ohio, Alabama, Iowa, Kentucky, Indiana, and Tennessee. Shaking was widespread, being felt across 23 states and even in Canada. At least two people died and seven were injured.
On 30 November 1973, at 07:48 UTC, a Mw 4.7 earthquake struck 1 km (0.62 mi) north-east of Alcoa, in the U.S. state of Tennessee. The earthquake was felt 2,100 km2 (810 sq mi) in the area. It was the most powerful known earthquake generated by the Eastern Tennessee seismic zone.
References
- 1 2 3 "M4.6 Fort Payne, Alabama Earthquake of 29 April 2003" (PDF). Prepared by U.S. Geological Survey National Earthquake Information Center. 13 June 2003. Archived from the original (PDF) on 4 January 2011.
- ↑ "Seismic Zones Affecting Alabama". Geological Survey of Alabama; Geologic Hazards Program. Archived from the original on 3 January 2011.
- ↑ "How likely is an earthquake?". Alabama Emergency Management Agency. Archived from the original on 2013-04-25. Retrieved 2012-11-12.
- ↑ Steltenpohl, Mark G.; Zeitz, Isidore; Horton, J. Wright Jr.; Daniels, David L. (27 January 2010). "New York–Alabama lineament: A buried right-slip fault bordering the Appalachians and mid-continent North America". Geology. 38 (6): 571–574. Bibcode:2010Geo....38..571S. doi:10.1130/G30978.1.