Aftershock 2013
Rosham Rosebure
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.
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 pattern of aftershocks helps confirm the size of area that slipped during the main shock. In both the 2004 Indian Ocean earthquake and the 2008 Sichuan earthquake, the aftershock distribution in each case showed that the epicenter (where the rupture initiated) lay to one end of the final area of slip, implying strongly asymmetric rupture propagation.
The frequency of aftershocks decreases roughly with the reciprocal of time after the main shock. This empirical relation was first described by Fusakichi Omori in 1894 and is known as Omori's law.[1] It is expressed as
According to these equations, the rate of aftershocks decreases quickly with time. The rate of aftershocks is proportional to the inverse of time since the mainshock and this relationship can be used to estimate the probability of future aftershock occurrence.[4] Thus whatever the probability of an aftershock are on the first day, the second day will have 1/2 the probability of the first day and the tenth day will have approximately 1/10 the probability of the first day (when p is equal to 1). These patterns describe only the statistical behavior of aftershocks; the actual times, numbers and locations of the aftershocks are stochastic [citation needed], while tending to follow these patterns. As this is an empirical law, values of the parameters are obtained by fitting to data after a mainshock has occurred, and they imply no specific physical mechanism in any given case.
The Utsu-Omori law has also been obtained theoretically, asthe solution of a differential equation describing the evolution of the aftershock activity,[5] where the interpretation of the evolution equation is based on the idea of deactivation of the faults in the vicinity of the main shock of the earthquake. Also, previously Utsu-Omori law was obtained from a nucleation process.[6] Results show that the spatial and temporal distribution of aftershocks is separable into a dependence on space and a dependence on time. And more recently, through the application of a fractional solution of the reactive differential equation,[7] a double power law model shows the number density decay in several possible ways, among which is a particular case the Utsu-Omori Law.
Land movement around the New Madrid is reported to be no more than 0.2 mm (0.0079 in) a year,[10] in contrast to the San Andreas Fault which averages up to 37 mm (1.5 in) a year across California.[11] Aftershocks on the San Andreas are now believed to top out at 10 years while earthquakes in New Madrid were considered aftershocks nearly 200 years after the 1812 New Madrid earthquake.[12]
Some scientists have tried to use foreshocks to help predict upcoming earthquakes, having one of their few successes with the 1975 Haicheng earthquake in China. On the East Pacific Rise however, transform faults show quite predictable foreshock behaviour before the main seismic event. Reviews of data of past events and their foreshocks showed that they have a low number of aftershocks and high foreshock rates compared to continental strike-slip faults.[13]
Following a large earthquake and aftershocks, many people have reported feeling "phantom earthquakes" when in fact no earthquake was taking place. This condition, known as "earthquake sickness" is thought to be related to motion sickness, and usually goes away as seismic activity tails off.[16][17]
Just to add, the Aftershock idol spawns an aftershock on a nearby ENEMY, the training dummy is a neutral mob not an enemy.
I tested the idol on bosses with the Lethargy node and that beeing the only source of slow on the build and it feels like it does not proc. If i manually hit Earthquake the boss gets slowed, if i just hit it with a Tempest Strike that has something like 7 attacks a second it does not proc at all.
Aftershocks are smaller earthquakes that occur in the same general area during the days to years following a larger event or "mainshock." They occur within 1-2 fault lengths away and during the period of time before the background seismicity level has resumed. As a general rule, aftershocks represent minor readjustments along the portion of a fault that slipped at the time of the mainshock. The frequency of these aftershocks decreases with time. Historically, deep earthquakes (>30 km) are much less likely to be followed by aftershocks than shallow earthquakes.
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Start with our Earthquake Hazards Education site. That includes: Earthquakes for Kids Cool Earthquake Facts Earthquake Science for Everyone Other good starting points include: State Geological Surveys for states in earthquake-prone regions The Great ShakeOut Earthquake Drills website SAGE (Seismological Facility for the Advancement of Geoscience), which is a non-profit consortium
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