Aftershocks

AFTERSHOCK Similar to a flashback with LSD, this is the reoccurrence of symptoms associated with taking PCP days, weeks, or months after taking the drug. This happens because PCP is stored in fatty cells in the body. 

Even one dose of PCP can lead to aftershocks, which are similar to the flashbacks experienced by some LSD users. Aftershocks are a re-experiencing of some or all of the effects of PCP intoxication, and can occur weeks, or months after the drug was taken. They have a physical, not psychological, cause. PCP stays in the parts of the body high in fat or oil, like the brain, liver, and fat... 

Lessons learned Exposure to C. immitis may have occurred among residents of and travelers to Ventura County, Los Angeles County, or other counties in or near the San Joaquin Valley following the earthquake and its aftershocks and during cleanup activities. Following earthquakes where C. immitis occurs, health advisories should be developed and broadcast, using the Health Alert Network, to health departments across the United States. These advisories should advise health professionals to be aware of potential exposure in persons who recently traveled to the impacted area. 

Revealed truth. What happened to the McKennas up the Amazon was one of those sudden, shattering discontinuities that sever the recipient from normal time, normal experience, and usually force a complete rewriting of one s life. Time is separated into those things that occurred before the revelation and those things that have come after—the aftershocks. 

As the fracture propagates, the elastic energy released due to the micro-fractures occurring within the sample can be measured. This ultrasonic emission due to micro-fracture aftershock relaxation has recently been measured for various laboratory samples. Petri et al (1994) measured the ultrasonic emission amplitude distribution in a large number of stressed solid samples under different experimental conditions. A power law decay for the cumulative energy release distribution n Er) with the released energy amplitude Er was observed in all cases n Er) E (see Fig. 3.21). This is indeed very similar to the Guttenberg-Richter law for the frequency distribution of earthquakes, as discussed briefly in Chapter 1, and will be discussed in detail in the next chapter. 

During the initial phase of the inspection the highest priority should be given to techniques for capturing the shortest-lived phenomena, such as aftershocks. The narrowing of the search area has to be conducted with the least intrusive procedures... 

Cavity aftershocks Underground cavity and rubble zone Surface cratering X X X X X X ... 

Nur, a. Booker, J.R. (1971) Aftershocks caused by pore fluid flow Science, 175, 885-887. 

A key problem is the evaluation of the relevance of observed seismicity patterns. First, it is important to decide whether an observed pattern has a physical origin or is an artifact, arising for example from inhomogeneous reporting or from man-made seismicity, like quarry blasts or explosions. Second, the non-artifical events have to be analyzed with respect to their underlying mechanisms. This leads to an inverse problem with a nonunique solution, which can be illustrated for the most pronounced observed seismicity pattern, the occurrence of aftershocks. It is empirically known... 

The most pronounced pattern in observed seismicity is the emergence of strongly clustered aftershock activity following a large earthquake. Apart from the Omori law (Eq. (14.2)), it is widely accepted that aftershocks are characterized by the following properties ... 

The aftershock rate scales with the mainshock size [38]. 

Aftershocks occur predominantly at the edges of the ruptured fault... 

Deviations from the Omori law, especially for rough faults, are discussed in [33]. While aftershocks are observed after almost all large earthquakes, foreshocks occur less frequent [51]. As a consequence, much less is known about the properties of these events. Kagan and Knopoff [29] and Jones and Molnar [28] propose a power law increase of activity according to an... 

It is not surprising that a model which imposes only tectonic loading and coseismic stress redistribution, produces no aftershocks, because it is likely that aftershocks are due to additional mechanisms triggered by the mainshock. A discussion on candidates for such mechanisms is given in [58]. A common feature is the presence of postseismic stress which generates aftershock activity. In [22], for instance, postseismic stress has been attributed to a viscoelastic relaxation process following the main-... 

Fig. 14.11. Frequency-magnitude distribution of all earthquakes, foreshocks and aftershocks, respectively. Foreshocks and aftershocks are defined as earthquakes occurring within one month before and after an earthquake with M > 6.

Khatiashvili N G, Perel man M E. On the mechanism of seismo-electromagnetic phenomena and their possible role in the electromagnetic radition during periods of earthquakes, foreshocks and aftershocks. Phys Earth Planet Inter. 1 169. 

The micro-seismic can be classified into 3 phases according to their frequency and intensity, e.g. the energy accumulation phase, frequent micro-seismic phase and aftershock phase. 

U.S. Department of Commerce Report 1966. The Prince William Sound, Alaska Earthquake of /964 and Aftershocks, Vol. 1, Publication 10-3, Coast and Geodetic Survey, Washington, DC, pp. 230-238. 

It was also noticed that the subsidence of the southern area increases proportionally with the distance from the fault. This is obvious at the control point 25 where the vertical displacement is 109mm between III - I epochs. This can be also explained apart from the aftershock movements by the following interpretation almost the whole southern part has been created by deposits from two existing torrents while at the same time an intensive withdrawal of underground water is still taking place. 

Classification for the resistance to earthquakes, with reference to the need that the component continue to be undamaged or functional during and after an earthquake of a certain severity, taking into account the aftershocks and therefore the possible incremental damage. 

Mogi already knew examples for induced events from the aftershock series of earthquakes after a large main shock and from clusters of volcanic earthquakes. After the main shock at t = 0 the event rate of aftershocks has been found to decay with time according to an empirical relation... 

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