Several significant earthquakes occurred in 2013, including two magnitude 8.0 or greater temblors according to the U.S. Geological Survey. Seventeen earthquakes reached magnitude 7.0-7.9 and two in the range of 8.0-8.9.
The USGS measured 1194 quakes magnitude 5.0 or larger in 2013. This is a number that changes annually; in 2012, 1558 quakes magnitude 5.0 or larger were measured, and in 2011, 2495.
Earthquakes were responsible for about 1400 deaths in 2013, with 825 having perished in the magnitude 7.7 Pakistan event on Sept. 24, as reported by the United Nations Office for Coordination of Humanitarian Affairs. Deadly quakes also occurred in the Philippines, Iran, China, Indonesia, the Santa Cruz Islands and Afghanistan.
The biggest earthquake in the United States and the 6th largest quake of 2013 was a magnitude 7.5 in Craig, Alaska on Jan. 5. Several quakes below magnitude 5.0 rattled Oklahoma, Texas, Kansas and Arkansas throughout the year. An unusual seismic event happened near Chicago, Ill. on Nov. 4; a magnitude 3.2 rockburst that occurred within seconds after a routine explosion at a quarry.
The USGS estimates that several million earthquakes occur throughout the world each year, although most go undetected because they hit remote areas or have very small magnitudes. On average, the USGS National Earthquake Information Center publishes the locations for about 40 earthquakes per day, or about 14,500 annually. USGS publishes worldwide earthquakes with a magnitude of 4.5 or greater or U.S. earthquakes of 2.5 or greater. On average, 18 of these earthquakes have a magnitude of 7.0 or higher each year.
To monitor earthquakes worldwide, the USGS National Earthquake Information Center receives data in real-time from about 1,000 stations in 85 countries, including the 150-station Global Seismographic Network, which is jointly supported by the USGS and the National Science Foundation and operated by the USGS in partnership with the Incorporated Research Institutions for Seismology (IRIS) consortium of universities. Domestically, the USGS partners with 13 regional seismic networks operated by universities; these networks provide detailed coverage for the areas of the country with the highest seismic risk.
Earthquakes pose significant risk to 75 million Americans in 39 States. The USGS and its partners in the multi-agency National Earthquake Hazard Reduction Program are working to improve earthquake monitoring and reporting capabilities via the USGS Advanced National Seismic System. More information about ANSS can be found on the ANSS website.