Oklahoma

From: Wikipedia - 2009–16 Oklahoma earthquake swarms

This presentation is drawn from the cited wiki but reorganized and shortened. Graphics are from AGU Publications.

Earthquakes recorded before 2009 in Oklahoma

September 1918 - First earthquake known to have occurred:

        A series of shocks were felt in El Reno, Oklahoma. Strongest intensity V on September 10.

September 27, 1929 - Second Earthquake known to have occurred: 

          Intensity VI. Centered in the El Reno area and was felt in central and western Oklahoma. Minor damage occurred in nearby areas and one chimney fell. The total affected area was approximately 20,000 km² (7,700 sq mi).[13]

April 9, 1952 at 10:29 a.m. CST (16:29 UTC) - Third Earthquake known to have occurred: 

              Near El Reno. The strongest earthquake ever recorded in Oklahoma. Magnitude 5.5. Most of Oklahoma was affected, as were parts of Arkansas, Iowa, Kansas, Missouri, Nebraska, and Texas. Damage was not extensive. Local residents were alarmed, and several thousands of dollars in damages occurred. Chimneys were toppled, walls were cracked, windows were broken, and bricks were loosened from buildings. In Oklahoma City, a crack measuring 15 meters (49 ft) was found in the State Capitol following the earthquake. The earthquake, which occurred along the Nemaha Fault, had a maximum intensity of VII near the epicenter.[13][14]

1952 - 1969 
 
Scattered earthquakes occurred in Oklahoma with intensities as high as VII.[13] Between 1978 and 2008, the average long-term rate of earthquakes was approximately two earthquakes of magnitude 3.0 or greater per year.[6]

Earthquakes recorded After 2009 in Oklahoma

2009

The previous low occurrence of earthquakes changed. Numbers jumped to 20 with the beginning of several swarms of earthquakes in Oklahoma.[15] Research suggests that most of the significant earthquakes in Oklahoma since the 1930s may have been induced by oil production activities.[16]

In response to the major increase in earthquakes in the Central United States, the United States Geological Survey began developing a new seismic hazard model to account for risk associated with induced seismicity. To date, no fewer than six individual earthquake sequences in Oklahoma have been identified and named by the Oklahoma Geological Survey.[10] Other swarms have been observed in south-central Kansas and North Texas.

According to data from the United States Geological Survey, there have been approximately 1,875 earthquakes in Oklahoma with moment magnitudes greater than or equal to 3.0,[11] about 62 earthquakes with magnitudes greater than or equal to 4.0, and two earthquakes with magnitudes greater than 5.0 associated with the earthquake swarms from the beginning of 2009 through February 20, 2016.[12]