1960 Valdivia earthquake
The 1960 Valdivia earthquake () or Great Chilean earthquake ("Gran terremoto de Chile") of 22 May is the most powerful earthquake ever recorded. Various studies have placed it at 9.4–9.6 on the moment magnitude scale. It occurred in the afternoon (19:11 GMT, 15:11 local time), and lasted approximately 10 minutes. The resulting tsunami affected southern Chile, Hawaii, Japan, the Philippines, eastern New Zealand, southeast Australia and the Aleutian Islands.
2009–19 Oklahoma earthquake swarms
A rise in seismicity in Oklahoma was observed in 2011. Early on the morning of November 5, 2011, an earthquake with a magnitude of 4.8 struck an area east of Oklahoma City roughly centered between Sparks and Prague. At the time, it was the strongest earthquake associated with the rise in Oklahoma's seismicity. Less than a day later at 10:53 p.m., a 5.6 M earthquake occurred near the location of the preceding 4.8 magnitude earthquake, becoming the strongest earthquake observed with any of the swarms as well as the strongest earthquake in the history of Oklahoma. This also resulted in the reclassification of the magnitude 4.8 earthquake as a foreshock and the 5.6 magnitude earthquake as the mainshock. The earthquake received over 66,000 "Did You Feel It?" responses nationwide sent to the United States Geological Survey. It was believed that the earthquake had occurred along the Wilzetta Fault, also known as the Seminole Uplift. Following this earthquake, several portable seismograph stations were established by the USGS, OGS, and University of Oklahoma School of Geology and Geophysics to aid with detection of future earthquakes in the area. The 5.6 M mainshock was followed by a magnitude 4.8 aftershock slightly under two days later, and numerous other aftershocks occurred in the following months. Through the end of 2011, 64 earthquakes were recorded, nearly double the number recorded for 2010.