Seismology is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other planet-like bodies. The field also includes studies of earthquake environmental effects such as tsunamis as well as diverse seismic sources such as volcanic, tectonic, oceanic, atmospheric, and artificial processes such as explosions. A related field that uses geology to infer information regarding past earthquakes is paleoseismology. A recording of earth motion as a function of time is called a seismogram. A seismologist is a scientist who does research in seismology.
The term intraplate earthquake refers to a variety of earthquake that occurs within the interior of a tectonic plate; this stands in contrast to an interplate earthquake, which occurs at the boundary of a tectonic plate.
The New Madrid Seismic Zone, 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.
An active fault is a fault that is likely to become the source of another earthquake sometime in the future. Geologists commonly consider faults to be active if there has been movement observed or evidence of seismic activity during the last 10,000 years.
Peak ground acceleration (PGA) is equal to the maximum ground acceleration that occurred during earthquake shaking at a location. PGA is equal to the amplitude of the largest absolute acceleration recorded on an accelerogram at a site during a particular earthquake. Earthquake shaking generally occurs in all three directions. Therefore, PGA is often split into the horizontal and vertical components. Horizontal PGAs are generally larger than those in the vertical direction but this is not always true, especially close to large earthquakes. PGA is an important parameter for earthquake engineering, The design basis earthquake ground motion (DBEGM) is often defined in terms of PGA.
Megathrust earthquakes occur at subduction zones at destructive convergent plate boundaries, where one tectonic plate is forced underneath another. These interplate earthquakes are the planet's most powerful, with moment magnitudes (Mw) that can exceed 9.0. Since 1900, all earthquakes of magnitude 9.0 or greater have been megathrust earthquakes. No other type of known terrestrial source of tectonic activity has produced earthquakes of this scale.
Earthscope is an earth science program using geological and geophysical techniques to explore the structure and evolution of the North American continent and to understand the processes controlling earthquakes and volcanoes. The project has three components: USARRAY, the Plate Boundary Observatory, and the San Andreas Fault Observatory at Depth.
The Indian subcontinent has a history of devastating earthquakes. The major reason for the high frequency and intensity of the earthquakes is that the Indian plate is driving into Asia at a rate of approximately 47 mm/year. Geographical statistics of India show that almost 54% of the land is vulnerable to earthquakes. A World Bank and United Nations report shows estimates that around 200 million city dwellers in India will be exposed to storms and earthquakes by 2050. The latest version of seismic zoning map of India given in the earthquake resistant design code of India [IS 1893 2002] assigns four levels of seismicity for India in terms of zone factors. In other words, the earthquake zoning map of India divides India into 4 seismic zones unlike its previous version, which consisted of five or six zones for the country. According to the present zoning map, Zone 5 expects the highest level of seismicity whereas Zone 2 is associated with the lowest level of seismicity.
Seismic magnitude scales are used to describe the overall strength or "size" of an earthquake. These are distinguished from seismic intensity scales that categorize the intensity or severity of ground shaking (quaking) caused by an earthquake at a given location. Magnitudes are usually determined from measurements of an earthquake's seismic waves as recorded on a seismogram. Magnitude scales vary on what aspect of the seismic waves are measured and how they are measured. Different magnitude scales are necessary because of differences in earthquakes, the information available, and the purposes for which the magnitudes are used.
The 1999 Chamoli earthquake occurred on 29 March in the Chamoli district in the Indian state of Uttar Pradesh. The earthquake was the strongest to hit the foothills of the Himalayas in more than ninety years. Approximately 103 people died in the earthquake.
The European Alert System is an earthquake warning system for member states of the Council of Europe's EUR-OPA Major Hazards Agreement.
The Swiss Seismological Service at ETH Zurich is the federal agency responsible for monitoring earthquakes in Switzerland and its neighboring countries and for assessing Switzerland’s seismic hazard. When an earthquake happens, the SED informs the public, authorities, and the media about the earthquake’s location, magnitude, and possible consequences. The activities of the SED are integrated in the federal action plan for earthquake precaution.
The 1984 Northern Sumatra earthquake occurred with a moment magnitude of 7.2 on November 17 at 06:49 UTC. The epicentre was located off the coast of Sumatra, near the island of Nias, where building damage was reported. This earthquake could be strongly felt in parts of Northern Sumatra, including Padang and Medan. The focal mechanism corresponded to reverse faulting.
Although the eastern United States is not as seismically active as regions near plate boundaries, large and damaging earthquakes do occur there. Furthermore, when these rare eastern U.S. earthquakes occur, the areas affected by them are much larger than for western U.S. earthquakes of the same magnitude. Thus, earthquakes represent at least a moderate hazard to East Coast cities, including New York City and adjacent areas of very high population density.
Chittenipattu Puthenveettil Rajendran, also known among his peers as CP is an Indian geologist who has worked mainly in paleoseismology and Indian geology.
The 2012 Indian Ocean earthquakes were magnitude 8.6 and 8.2 Mw undersea earthquakes that struck near the Indonesian province of Aceh on 11 April at 15:38 local time. Initially, authorities feared that the initial earthquake would cause a tsunami and warnings were issued across the Indian Ocean; however, these warnings were subsequently cancelled. These were unusually strong intraplate earthquakes and the largest strike-slip earthquake ever recorded.
Weston Observatory is a geophysical research laboratory of the Department of Earth and Environmental Sciences at Boston College. The Observatory is located in the town of Weston, Massachusetts, about 13 miles (21 km) west of downtown Boston.
Kyrgyz Seismic Network. The territory of Kyrgyzstan is characterized by high seismicity. About three thousand earthquakes occur on average each year with magnitude up to eight points. Therefore, seismic monitoring is of crucial importance to the country.
The University of QueenslandSeismology Station was established in 1938 at the University of Queensland, Brisbane, Australia.
