An earthquake is a shaking of the ground caused by movement of the earth's crust. a sudden shaking of the earth's surface that often causes a lot of damage. Sudden disturbance within the Earth manifested at the surface by a shaking of the ground caused by seismic waves. The origin and distribution of most major earthquakes can be explained in terms of faults and the plate tectonics theory. Earthquake magnitude (a quantitative measure of amplitude and energy released) is usually expressed in terms of the Richter scale. Earthquake intensity is rated on the Mercalli scale, based on a qualitative measure (e.g., "barely felt" or "catastrophic destruction") of damage to terrain and structures at any given location. In general, a quake's intensity decreases with distance from its epicentre, but other factors, including surface geology, may significantly influence its effects. See also seismology
A naturally occurring shaking motion of the Earth's surface Earthquakes are caused when stress, building up within rocks of the Earth's crust, is released in a sudden jolt
violent tremor of the earth's crust which originates naturally and below the surface
a disturbance that is extremely disruptive; "selling the company caused an earthquake among the employees"
Sudden motion in Earth caused by abrupt release of slowly accumulated strain Shaking of the Earth caused by a sudden movement of rock beneath its surface
{i} trembling of the earth (usually produced by volcanic action or other forces under the earth's crust)
shaking and vibration at the surface of the earth resulting from underground movement along a fault plane of from volcanic activity a disturbance that is extremely disruptive; "selling the company caused an earthquake among the employees
A series of elastic waves propagated in Earth, initiated where stress along a fault exceeds the elastic limit of the rock so that sudden movement occurs along the fault
The wave of shock sometimes traverses half a hemisphere, destroying cities and many thousand lives; called also earthdin, earthquave, and earthshock
Ground shaking and radiated seismic energy caused most commonly by sudden slip on a fault, volcanic or magmatic activity, or other sudden stress changes in the Earth An earthquake of magnitude 8 or larger is termed a great earthquake Earthquake hazard Any physical phenomenon associated with an earthquake that may produce adverse effects on human activities This includes surface faulting, ground shaking, landslides, liquefaction, tectonic deformation, tsunami, and seiche and their effects on land use, manmade structures, and socioeconomic systems A commonly used restricted definition of earthquake hazard is the probability of occurrence of a specified level of ground shaking in a specified period of time Earthquake risk The expected (or probable) life loss, injury, or building damage that will happen, given the probability that some earthquake hazard occurs Earthquake risk and earthquake hazard are occasionally used interchangeably
A shaking of the earth caused by a sudden movement of rock beneath the Earth's surface An earthquake occurs on a fault, which is a thin layer of crushed rock between two blocks of rock A fault can range in length from a few centimeters to thousands of miles The San Andreas fault in California is 650 miles long and ten miles deep in places Stresses in the earth's outer layer push the sides of the fault together Stress builds up and the rocks slip suddenly, releasing energy in waves that travel through the rock to cause the shaking that we feel during an earthquake The National Earthquake Information Center locates about 12,000 to 14,000 earthquakes annually That's about 35 a day Based on long term historical records, about 18 major earthquakes (7 0 - 7 9 on the Richter scale) and one great earthquake (8 0 or above) are expected in any given year FEMA Earthquakes Backgrounder Earthquake Engineering Research Institute
A shaking, trembling, or concussion of the earth, due to subterranean causes, often accompanied by a rumbling noise
shaking and vibration at the surface of the earth resulting from underground movement along a fault plane of from volcanic activity
The sudden motion or trembling of the ground produced by abrupt displacement of rock masses, usually within the upper 10 to 20 miles of the earth's surface (FEMA definition)
A movement within the Earth's crust or mantle, caused by the sudden rupture or repositioning of underground rocks as they release stress
a shaking or trembling of the crust of the earth, caused by underground volcanic forces or by breaking and shifting of rock beneath the surface