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Today in Earthquake History: M7.6 - Costa Rica, 1991 Forty-seven people killed, 109 injured, 7,439 homeless and severe damage (IX) in the Limon-Pandora area. Intensity X was observed in some zones of liquefaction within the epicentral area. Some damage (VI) also occurred in the San Jose-Alajuela area and landslides blocked roads between Limon and central Costa Rica. Twenty-eight people killed, 454 injured, 2,400 homeless and 866 buildings destroyed (VII-VIII) in the Guabito-...Almirante-Bocas del Toro area, Panama. Slight damage (VI) also occurred at David and Puerto Armuelles, Panama. Felt (IV) at Colon and (III) at Panama City. Felt (III) in eastern El Salvador and (II) at San Salvador. Also felt in Nicaragua and Honduras and on San Andres Island, Colombia. Maximum uplift of 1.4 meters was observed near Limon and sandblows and liquefaction caused subsidence of soils in the Bocas del Toro area. Ground cracks also occurred in the epicentral area. A 2-meter tsunami with maximum runup of 300 meters was observed in the Cahuita-Puerto Viejo area, Costa Rica. Tsunamis were also reported on Bastimentos, Carenero and Colon Islands and at Portobelo, Panama. The maximum amplitude of the tsunami in Panama was about 0.6 m. A 7-cm tsunami (peak-to-trough) was recorded on the tide gauge at Cristobal, Panama. Damage in Costa Rica estimated to be about 43 million U.S. dollars See more

Earthquake Fact of the Day: The interior of Antarctica has icequakes. The icequakes are similar to earthquakes, but occur within the ice sheet itself instead of the land underneath the ice. Polar observers have told us they can hear the icequakes and see them on the South Pole seismograph station, but they are much too small to be seen on enough stations to obtain a location.

Earthquake Update: M2.7 - 7km WSW of Perry, Oklahoma on 2015-04-20 at 16:47:52 (UTC) Nearby Cities: 7km (4mi) WSW of Perry, Oklahoma 31km (19mi) WNW of Stillwater, Oklahoma 43km (27mi) N of Guthrie, Oklahoma... 48km (30mi) ESE of Enid, Oklahoma 89km (55mi) N of Oklahoma City, Oklahoma See more

Today in Earthquake History for April 21: M7.4 - Solomon Islands, 1977- 18 reported killed due to landslides. One reported injured at Honiara. Extensive damage on Guadacanal. Slight tsunami at Apia and Suva. Felt (VII) at Honiara.

Today in Earthquake History for April 21: M7.2 - Philippines, 1995 Some damage occurred at Borongan and Sulat. Felt (IV RF) at Butuan, Mindanao; (III RF) on Masbate; (II RF) on Cebu and at Cagayan de Oro, Mindanao. Also felt at Davao, Mindanao. Local tsunami generated with maximum wave heights (peak-to- trough) of 10 cm recorded at Legaspi, Luzon.

Earthquake Fact of the Day: The origin of the name of the San Andreas Fault is often cited as the San Andreas Lake. However, based on some 1895 and 1908 reports by geologist A.C. Lawson, who named the fault, the name was actually taken from the San Andreas Valley. Lawson likely did not realize at the time that the fault ran almost the entire length of California.

Seismic Activity in the US for 2/19/2015: We return today to Oklahoma for a 3.3 rated seismic event. This is a continuing trend in the state, one that is getting noticed now on the national level. An AP story can be found in yesterday's Newsday or by following the link below for Yahoo. This ongoing string of seismic events has been linked by some scientists to fracking and other manmade activities, while others believe that there is not enough evidence supporting these claim...s. What do you think? Comment below! http://news.yahoo.com/study-oklahomas-daily-small-quakes-ra

Seismic Activity in the US for 2/17/2015: For today, we are going on an international spin, off to New Zealand, just off the main northern island and to the Kermadec Islands. The Kermadec Islands /krmædk/ are a subtropical island arc in the South Pacific Ocean 8001,000 km (500620 mi) northeast of New Zealand's North Island, and a similar distance southwest of Tonga. The islands are part of New Zealand, 33 km2 (12.7 sq mi) in total area and nowadays uninhabited, except for the permanently manned Raoul Island Station, the northernmost outpost of New Zealand (Wikipedia). Two earthquakes today were reported, a 5.2 right of the northern shore of the North Island, and a 4.8 a 1,000 miles north, at the Kermadec Islands. This is after a 6.0 shook the island nation of New Zealand about a month ago, on Jan. 6, 2015.

Seismic Activity in the US for 2/13/2015: Today, three earthquakes have hit the the Aleutian arc, from the western islands to part of the mainland. A widespread, but all part of the same fault system, these earthquakes have a minute range in magnitudes, 2.6 to 2.7. The curvature of the arc results in a westward transition of relative plate motion from trench-normal (i.e., compressional) in the east to trench-parallel (i.e., translational) in the west, accompanied by westward ...variations in seismic activity, volcanism, and overriding plate composition. The Aleutian arc is generally divided into three regions: the western, central, and eastern Aleutians. Relative to a fixed North America plate, the Pacific plate is moving northwest at a rate that increases from roughly 60 mm/yr at the arc's eastern edge to 76 mm/yr near its western terminus. The eastern Aleutian arc extends from the Alaskan Peninsula in the east to the Fox Islands in the west. Motion along this section of the arc is characterized by arc-perpendicular convergence and Pacific plate subduction beneath thick continental lithosphere. This region exhibits intense volcanic activity and has a history of megathrust earthquakes. See more

Seismic Activity in the US for 2/12/2015: Just to feel a little warmer for a change, we head to Hawaii for our seismic activity today. We go to Pahala, on the southern tip of the Main Island of Hawaii. Nestled south and between the volcanic activity of the main islands active volcanoes, Pahala is very susceptible to seismic activity. The Island of Hawaii experiences thousands of earthquakes each year; most are so small that they can only be detected by instruments, but some a...re strong enough to be felt, and a few cause minor-to-moderate damage. Most of Hawaii's earthquakes are directly related to volcanic activity and are caused by magma moving beneath the earth's surface. Earthquakes may occur before or during an eruption, or they may result from the underground movement of magma that comes close to the surface but does not erupt. A few of the island's earthquakes are less directly related to volcanism; these earthquakes originate in zones of structural weakness at the base of the volcanoes or deep within the earth beneath the island. See more

Seismic Activity in the US for 2/11/2015: Oregon was struck earlier today with a pair of 2.8-2.9 tremors. Low on the Richter Scale. The table on Wikipedia for the scale is very useful and can be used as a good learning tool. The table states the earthquakes in the range of today's event in Oregon will have caused some shaking, felt by people, but causing no structural damage. http://earthquake.usgs.gov/earthquakes/... http://en.wikipedia.org/wiki/Richter_magnitude_scale See more

Seismic Activity in the US for 2/10/2015: We return to the Kansas-Oklahoma border for today's report. A 3.6 in Kansas and a 2.8 in Oklahoma have been reported today. This continues a steady stream of seismic events coming from this central area of the United States. Most earthquakes in North America east of the Rockies occur as faulting within bedrock, usually miles deep. Few earthquakes east of the Rockies, however, have been definitely linked to mapped geologic faults, in ...contrast to the situation at plate boundaries such as California's San Andreas fault system, where scientists can commonly use geologic evidence to identify a fault that has produced a large earthquake and that is likely to produce large future earthquakes. Scientists who study eastern and central North America earthquakes often work from the hypothesis that modern earthquakes occur as the result of slip on preexisting faults that were formed in earlier geologic eras and that have been reactivated under the current stress conditions. The bedrock of Eastern North America is, however, laced with faults that were active in earlier geologic eras, and few of these faults are known to have been active in the current geologic era. In most areas east of the Rockies, the likelihood of future damaging earthquakes is currently estimated from the frequencies and sizes of instrumentally recorded earthquakes or earthquakes documented in historical records. The Mid-Atlantic Ridge, a submerged mountain range, which extends from the Arctic Ocean to beyond the southern tip of Africa, is a divergent tectonic plate boundary. It is just one segment of the global mid-ocean ridge system that encircles the Earth. The rate of spreading along the Mid-Atlantic Ridge averages about 2.5 centimeters per year, or 25 km in a million years. The Mid-Atlantic Ridge separates the Eurasian Plate and the North American Plate in the North Atlantic, and separates the African Plate from the South American Plate in the South Atlantic. http://earthquake.usgs.gov/earthquakes/

Seismic Activity in the US for 2/9/2015: Today back to back earthquakes, a 3.3 and a 2.9, hit California, near The Geysers, CA. This is in northern California, west of Sacramento. It lies in a very active fault region, the San Andreas being the largest, but many smaller faults lie inland, mostly along the Sierra Nevadas, causing many minor earthquakes in the interior of California.