|
Remotely Triggered Earthquakes
Remotely triggered earthquakes are a result of the effects of large earthquakes at considerable distance, outside of the immediate aftershock zone. The farther one gets from the initiating earthquake in both space and time, the more difficult it is to establish an association. The physics of triggering an earthquake are complex. Most earthquake-generating zones are in a state of being close to failure. If such a zone were to be left completely alone, it would generate significant earthquakes spontaneously. Remote earthquakes, however, are in a position to disturb this critical state, either by shifting the stresses statically, or by dynamic change caused by passing seismic waves. The first type of triggering may be due to static changes in the critical state. For example, after the magnitude 7.3 Landers earthquake struck California in 1992, it is said that "the earthquake map of California lit up like a Christmas tree". This event reinforced the idea of remotely triggered earthqua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earthquake
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from those that are so weak that they cannot be felt, to those violent enough to propel objects and people into the air, damage critical infrastructure, and wreak destruction across entire cities. The seismic activity of an area is the frequency, type, and size of earthquakes experienced over a particular time period. The seismicity at a particular location in the Earth is the average rate of seismic energy release per unit volume. The word ''tremor'' is also used for non-earthquake seismic rumbling. At the Earth's surface, earthquakes manifest themselves by shaking and displacing or disrupting the ground. When the epicenter of a large earthquake is located offshore, the seabed may be displaced sufficiently to cause a tsunami. Earthquakes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aftershock
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 nearly identical seismic waveforms. Distribution of aftershocks Most aftershocks are located over the full area of fault rupture and either occur along the fault plane itself or along other faults within the volume affected by the strain associated with the main shock. Typically, aftershocks are found up to a distance equal to the rupture length away from the fault plane. The patte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1992 Landers Earthquake
The 1992 Landers earthquake occurred on Sunday, June 28 with an epicenter near the town of Landers, California, in San Bernardino County. The shock had a moment magnitude of 7.3 and a maximum Mercalli intensity of IX (''Violent''). Earthquake At 4:57 a.m. local time (11:57 UTC) on June 28, 1992, a magnitude 7.3 earthquake awoke much of Southern California. Though it turned out it was not the so-called " Big One" as many people would think, it was still a very strong earthquake. The shaking lasted for two to three minutes. Although this earthquake was much more powerful than the 1994 Northridge earthquake, the damage and loss of life were minimized by its location in the sparsely-populated Mojave Desert. The earthquake was a right-lateral strike-slip event, and involved the rupture of several different faults over a length of . The names of those that were involved are the Johnson Valley, Kickapoo (also known as Landers), Homestead Valley, Homestead/Emerson, Emerson Va ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2004 Indian Ocean Earthquake And Tsunami
An earthquake and a tsunami, known as the Boxing Day Tsunami and, by the scientific community, the Sumatra–Andaman earthquake, occurred at 07:58:53 local time ( UTC+7) on 26 December 2004, with an epicentre off the west coast of northern Sumatra, Indonesia. It was an undersea megathrust earthquake that registered a magnitude of 9.1–9.3 , reaching a Mercalli intensity up to IX in certain areas. The earthquake was caused by a rupture along the fault between the Burma Plate and the Indian Plate. A series of massive tsunami waves grew up to high once heading inland, after being created by the underwater seismic activity offshore. Communities along the surrounding coasts of the Indian Ocean were devastated, and the tsunamis killed an estimated 227,898 people in 14 countries, making it one of the deadliest natural disasters in recorded history. The direct results caused major disruptions to living conditions and commerce in coastal provinces of surrounded countries, incl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Science (journal)
''Science'', also widely referred to as ''Science Magazine'', is the peer-reviewed academic journal of the American Association for the Advancement of Science (AAAS) and one of the world's top academic journals. It was first published in 1880, is currently circulated weekly and has a subscriber base of around 130,000. Because institutional subscriptions and online access serve a larger audience, its estimated readership is over 400,000 people. ''Science'' is based in Washington, D.C., United States, with a second office in Cambridge, UK. Contents The major focus of the journal is publishing important original scientific research and research reviews, but ''Science'' also publishes science-related news, opinions on science policy and other matters of interest to scientists and others who are concerned with the wide implications of science and technology. Unlike most scientific journals, which focus on a specific field, ''Science'' and its rival ''Nature'' cover the full r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Discrete Element Method
A discrete element method (DEM), also called a distinct element method, is any of a family of numerical methods for computing the motion and effect of a large number of small particles. Though DEM is very closely related to molecular dynamics, the method is generally distinguished by its inclusion of rotational degrees-of-freedom as well as stateful contact and often complicated geometries (including polyhedra). With advances in computing power and numerical algorithms for nearest neighbor sorting, it has become possible to numerically simulate millions of particles on a single processor. Today DEM is becoming widely accepted as an effective method of addressing engineering problems in granular and discontinuous materials, especially in granular flows, powder mechanics, and rock mechanics. DEM has been extended into the Extended Discrete Element Method taking heat transfer, chemical reaction and coupling to CFD and FEM into account. Discrete element methods are relatively com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Landslide
Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, deep-seated slope failures, mudflows, and debris flows. Landslides occur in a variety of environments, characterized by either steep or gentle slope gradients, from mountain ranges to coastal cliffs or even underwater, in which case they are called submarine landslides. Gravity is the primary driving force for a landslide to occur, but there are other factors affecting slope stability that produce specific conditions that make a slope prone to failure. In many cases, the landslide is triggered by a specific event (such as a heavy rainfall, an earthquake, a slope cut to build a road, and many others), although this is not always identifiable. Causes Landslides occur when the slope (or a portion of it) undergoes some processes that change its condition from stable to unstable. This is essentially due to a decrease in the shear stren ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fault Mechanics
Fault mechanics is a field of study that investigates the behavior of geologic faults. Behind every good earthquake is some weak rock. Whether the rock remains weak becomes an important point in determining the potential for bigger earthquakes. On a small scale, fractured rock behaves essentially the same throughout the world, in that the angle of friction is more or less uniform (see Fault friction). A small element of rock in a larger mass responds to stress changes in a well defined manner: if it is squeezed by differential stresses greater than its strength, it is capable of large deformations. A band of weak, fractured rock in a competent mass can deform to resemble a classic geologic fault. Using seismometers and earthquake location, the requisite pattern of micro-earthquakes can be observed. For earthquakes, it all starts with an embedded penny-shaped crack as first envisioned by Brune. As illustrated, an earthquake zone may start as a single crack, growing to f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tectonic Weapon
A tectonic weapon is a hypothetical device or system which could trigger earthquakes, volcanic eruptions, or other seismic events in specified locations by interfering with the Earth's natural geological processes. It was defined in 1992 by Aleksey Vsevolodovich Nikolayev, corresponding member of the Russian Academy of Sciences: "A tectonic or seismic weapon would be the use of the accumulated tectonic energy of the Earth's deeper layers to induce a destructive earthquake". He added "to set oneself the objective of inducing an earthquake is extremely doubtful." Though no such device is known to have been built, tectonic weapons have occasionally appeared as plot devices in works of fiction. Concept Theoretically, the tectonic weapon functions by creating a powerful charge of elastic energy in the form of deformed volume of the Earth's crust in a region of tectonic activity. This then becomes an earthquake once triggered by a nuclear explosion in the epicenter or a vast electric p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
