Search results
Results from the WOW.Com Content Network
In its most general sense, the word earthquake is used to describe any seismic event that generates seismic waves. Earthquakes can occur naturally or be induced by human activities, such as mining, fracking, and nuclear tests. The initial point of rupture is called the hypocenter or focus, while the ground level directly above it is the epicenter.
Seismic moment is a quantity used by seismologists to measure the size of an earthquake.The scalar seismic moment is defined by the equation =, where . is the shear modulus of the rocks involved in the earthquake (in pascals (Pa), i.e. newtons per square meter)
Submarine earthquake, an earthquake that occurs underwater at the bottom of a body of water, especially an ocean. [17] Supershear earthquake, an earthquake in which the propagation of the rupture along the fault surface occurs at speeds in excess of the seismic shear wave (S-wave) velocity, causing an effect analogous to a sonic boom. [18]
Japan's Earthquake Early Warning system was put to practical use in 2006. The system that warns the general public was installed on October 1, 2007. [25] [26] It was modeled partly on the Urgent Earthquake Detection and Alarm System (UrEDAS ) of Japan Railways, which was designed to enable automatic braking of bullet trains. [27]
An earthquake is a phenomenon that results from the sudden release of stored energy in the Earth's crust that creates seismic waves. At the Earth's surface, earthquakes may manifest themselves by a shaking or displacement of the ground and sometimes cause tsunamis, which may lead to loss of life and destruction of property. An earthquake is ...
Earthquakes: Shallow earthquakes can generate sound waves with little ground vibration: The "booming" sound is heard only locally, near the epicenter. [7] [8] Avalanches, either natural or human-caused (for avalanche control). Weather: Distant thunder, or loud sounds from wind damage.
Seismology (/ s aɪ z ˈ m ɒ l ə dʒ i, s aɪ s-/; 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.
Following an earthquake event, S waves arrive at seismograph stations after the faster-moving P waves and displace the ground perpendicular to the direction of propagation. Depending on the propagational direction, the wave can take on different surface characteristics; for example, in the case of horizontally polarized S waves, the ground ...