Seismology

thumb|upright=1.35|Earthquake epicenters occur mostly along tectonic plate boundaries, especially on the Pacific [[Ring of Fire.]]

scientific theory that describes the large-scale motions of Earth's lithosphere

thumb|Animation of tsunami triggered by the 2004 Indian Ocean earthquake Seismology (; from Ancient Greek σεισμός (seismós), meaning 'earthquake', and -λογία (-logía), meaning 'study of') is the scientific study of earthquakes (or generally, quakes) and the generation and propagation of elastic waves through planetary bodies. It also includes studies of the environmental effects of earthquakes such as tsunamis; other seismic sources such as volcanoes, plate tectonics, glaciers, rivers, oceanic microseisms, and the atmosphere; and artificial processes such as explosions.

thumb|upright=1.4|Badlands incised into [[shale at the foot of the North Caineville Plateau, Utah, within the pass carved by the Fremont River and known as the Blue Gate. G. K. Gilbert studied the landscapes of this area in great detail, forming the observational foundation for many of his studies on geomorphology.]] thumb|Surface of Earth, showing higher elevations in red

thumb|right|The epicenter is directly above the earthquake's [[hypocenter (also called the ).]]

A hypocenter or hypocentre, also called ground zero or surface zero, is the point on the Earth's surface directly below a nuclear explosion, meteor air burst, or other mid-air explosion. In seismology, the hypocenter of an earthquake is its point of origin below ground; a synonym is the focus of an earthquake.

seismic, volcanic, or explosive energy that travels through Earth's layers

In seismology, an aftershock is a smaller earthquake that follows a larger earthquake, in the same area of the main shock, caused as the displaced crust adjusts to the effects of the main shock. Large earthquakes can have hundreds to thousands of instrumentally detectable aftershocks, which steadily decrease in magnitude and frequency according to a consistent pattern. In some earthquakes the main rupture happens in two or more steps, resulting in multiple main shocks. These are known as doublet earthquakes, and in general can be distinguished from aftershocks in having similar magnitudes and

interdisciplinary branch of engineering

a type of reverse fault that has a dip of 45 degrees or less

geological phenomenon when soil material that is ordinarily a solid behaves like a liquid

strength of seismic waves of an earthquake

A foreshock is an earthquake that occurs before a larger seismic eventthe mainshockand is related to it in both time and space. The designation of an earthquake as foreshock, mainshock or aftershock is only possible after the full sequence of events has happened.

longitudinal seismic wave

mechanical wave that propagates along the interface between differing media

transverse seismic wave

type of surface wave caused due to earthquake

thumb|Illustration of the shadow zone of a P-wave for Earth. [[S-waves don't penetrate the outer core]] A marsquake is a quake which, much like an earthquake, is a shaking of the surface or interior of the planet Mars. Such quakes may occur with a shift in the planet's interior, such as the result of plate tectonics, from which most quakes on Earth originate, or possibly from hotspots such as Olympus Mons or the Tharsis Montes. The detection and analysis of marsquakes are informative to probing the interior structure of Mars, as well as potentially identifying whether any of Mars's many volcan

scale used to measure earthquake intensity

maximum ground acceleration during an earthquake at a location

type of map used in seismology

type of seismic wave

in seismology

process that generates seismic waves in an earthquake

earthquake caused by human activity (artificial lakes, mining, waste disposal wells, groundwater extraction, fracking etc.)

area not reached by seismic waves from an earthquake

thumb|220px|right|The "Serapium" or Macellum of Pozzuoli demonstrated the effects of bradyseism. Bradyseism is the gradual uplift (positive bradyseism) or descent (negative bradyseism) of part of the Earth's surface caused by the filling or emptying of an underground magma chamber or hydrothermal activity, particularly in volcanic calderas. It can persist for millennia in between eruptions and each uplift event is normally accompanied by thousands of small to moderate earthquakes. The word derives from the ancient Greek words βραδύς bradús, meaning "slow", and σεισμός seismós meaning "movement

scientific concept

A cryoseism, ice quake or frost quake, is a seismic event caused by a sudden cracking action in frozen soil or rock saturated with water or ice, or by stresses generated at frozen lakes.

surface shaking on interstellar bodies in general

earthquake caused by the movement of magma

deviation of seismic waves by rock or soil layers to characterize subsurface geologic structures

cone of sand formed by the ejection of sand onto a surface from a central point by water under pressure

method

In seismology, a microseism is defined as a faint earth tremor caused by natural phenomena. Sometimes referred to as a "hum", it should not be confused with the anomalous acoustic phenomenon of the same name. The term is most commonly used to refer to the dominant background seismic and electromagnetic noise signals on Earth, which are caused by water waves in the oceans and lakes. Characteristics of microseism are discussed by Bhatt. Because the ocean wave oscillations are statistically homogeneous over several hours, the microseism signal is a long-continuing oscillation of the ground. The m

Seismotectonics is the study of the relationship between the earthquakes, active tectonics and individual faults of a region. It seeks to understand which faults are responsible for seismic activity in an area by analysing a combination of regional tectonics, recent instrumentally recorded events, accounts of historical earthquakes and geomorphological evidence. This information can then be used to quantify the seismic hazard of an area.

International non-governmental association

collaboration of the U.S. Geological Survey (USGS) and regional, state, and academic partners

measurable surface displacement along a fault in the absence of notable earthquakes

explanation of how energy is released during an earthquake

In seismology, the mainshock is the largest earthquake in a sequence, sometimes preceded by one or more foreshocks, and almost always followed by many aftershocks.

earthquake with a hypocenter depth exceeding 300 km

hypothetical device or system which could create earthquakes

process

segment of an active fault known to produce significant earthquakes that has not slipped in an unusually long time

seismological phenomenon, caused by calving outlet glaciers of continental ice shields

thumb|Seismites in the Upper Ordovician of northern Kentucky. thumb|Seismite in Holocene sediments of the Dead Sea basin, Israel. thumb|Seismite in the Borden Formation, Ohio, demonstrating "flow rolls".

strongest part of the Earth's crust

Boundary between Earth's core and mantle

seismology

in seismology and earthquake engineering

classification

conveying information through mechanical (seismic) vibrations of the substrate

A microearthquake (or microquake) is a very low-intensity earthquake that is 2.0 or less in magnitude. They are very rarely felt beyond from their epicenter. In addition to having natural tectonic causes, they may also be seen as a result of underground nuclear testing or even large detonations of conventional explosives for producing excavations. They normally cause no damage to life or property, and are very rarely felt by people.