Is there always an aftershocf after an earthquake?
88247
yes, usually but sometimes they are so small they can't be felt.  If you go the usgs.gov website it will give you all the earthquakes which occur on a daily basis.  Most earthquakes that occur can't be felt on the surface.
1044728
The foci of earthquakes at transform boundaries tend to be at shallow depths.\n\nSee source.
13603
Yes, there are. I have experienced several including the Nisqually Earthquake on 2/28/2001 that registered 6.8 and caused a significant amount of damage. \n\nThe site I added below gives more information about the major faults that are located under the water near the city.
747847
I'm sorry to tell you that the spread of pathogens is an ever present danger during and after any earthquake. Just look at the recent example in Pakistan, just a few months ago. \nThey are thankful my fellow American doctors helped as much as humanly possible!\nTake care and be safe !!!
142274
I like this one  \nhttp://earthquake.usgs.gov/regional/neic/
568106
I'd say the chances are really good. There was a 3.1 earthquake on May 06, 2006 about 20 miles SW of Trinidad, Colorado (190 miles south of Denver).\n\nBetween August 28 and September 21, 2001 there was a swarm of 12 measuring from 2.8 to 4.6 near Trinidad.
1034765
It's impossible to say when an earthquake will strike, it's only possible to predict statistically when an earthquake might happen. However, this prediction will be so broad in real terms that it will have no value to anyone in terms of safety or doing anything pre-emptive.\n\n\nThe earthquake regions are however well known and follow the recognised earth's fault lines.\n\nIt will however give people some idea of the frequency or expectation of experiencing earthquakes in their own area and allow services to be put in place. The San Andreas fault is due to have another big one soon based on past patterns but the exact date cannot be predicted and I seem to remember reading that it's already late. Only when it's actually happened will it be possible to accurately predict when it was!
410632
the beginning of an earthquake are foreshocks. these foreshocks have P-waves, s-waves and surface waves attached to it.
1059131
In the sense of an earthquake, yeah.  That's what it is.  A wave of earth moving out from the central point of origin.  That has nothing to do with the wave-particle duality.  In fact, it's best not to think of it as an actual wave or an actual particle (like a billiard ball).
989327
Naturally occurring earthquakes\n\nMost naturally occurring earthquakes are related to the tectonic nature of the Earth. Such earthquakes are called tectonic earthquakes. The Earth's lithosphere is a patch work of plates (see plate tectonics) in slow but constant motion caused by the heat in the Earth's mantle and core. Plate boundaries glide past each other, creating frictional stress. When the frictional stress exceeds a critical value, called local strength, a sudden failure occurs. The boundary of tectonic plates along which failure occurs is called the fault plane. When the failure at the fault plane results in a violent displacement of the Earth's crust, the elastic strain energy is released and elastic waves are radiated, thus causing an earthquake. It is estimated that only 10 percent or less of an earthquake's total energy is ultimately radiated as seismic energy, while most of the earthquake's energy is used to power the earthquake fracture growth and is eventually converted into heat. Therefore, earthquakes lower the Earth's available potential energy and thermal energy, though these losses are negligible. To describe the physical process of occurrence of an earthquake, seismologists use the Elastic-rebound theory.\n\nThe majority of tectonic earthquakes originate at depths not exceeding a few tens of kilometers. Earthquakes occurring at boundaries of tectonic plates are called interplate earthquakes, while the less frequent events that occur in the interior of the lithospheric plates are called intraplate earthquakes.\n\nWhere the crust is thicker and colder, earthquakes occur at greater depths of hundreds of kilometers along subduction zones where plates descend into the Earth's mantle. These types of earthquakes are called deep focus earthquakes. They are possibly generated when subducted lithospheric material catastrophically undergoes a phase transition (e.g., olivine to spinel), releasing stored energy—such as elastic strain, chemical energy or gravitational energy—that cannot be supported at the pressures and temperatures present at such depths.\n\nEarthquakes may also occur in volcanic regions and are caused by the movement of magma in volcanoes. Such quakes can be an early warning of volcanic eruptions.\n\nA recently proposed theory suggests that some earthquakes may occur in a sort of earthquake storm, where one earthquake will trigger a series of earthquakes each triggered by the previous shifts on the fault lines, similar to aftershocks, but occurring years later, and with some of the later earthquakes as damaging as the early ones. Such a pattern was observed in the sequence of about a dozen earthquakes that struck the Anatolian Fault in Turkey in the 20th Century, the half dozen large earthquakes in New Madrid in 1811-1812, and has been inferred for older anomalous clusters of large earthquakes in the Middle East and in the Mojave Desert.\n\nInduced earthquakes\nSome earthquakes are the result of a number of anthropogenic sources, such as extraction of minerals and fossil fuel from the Earth's crust, the removal or injection of fluids into the crust, reservoir-induced seismicity, massive explosions, and collapse of large buildings. These seismic events caused by human activity are referred to by the term induced seismicity. They however are not strictly earthquakes and usually show a different seismogram than earthquakes that occur naturally.\n\nA rare few earthquakes have been associated with the build-up of large masses of water behind dams, such as the Kariba Dam in Zambia, Africa, and with the injection or extraction of fluids into the Earth's crust (e.g. at certain geothermal power plants and at the Rocky Mountain Arsenal). Such earthquakes occur because the strength of the Earth's crust can be modified by fluid pressure. Earthquakes have also been known to be caused by the removal of natural gas from subsurface deposits, for instance in the northern Net
502327
There was one yesterday on Leyte Philippines bad enough to wipe out the electricity for 75% of the Visayas, we lost power for a total of five hours.\nAt present there are conflicting reports as to it's strength, and the major earthquake reporting site hasn't recorded it.\nNow if we are talking big as in really big say a Nine or nearly, there are many places overdue an earthquake. So my answer would be very, very soon.
1118758
Following an earthquake you should examine your home for potentially dangerous objects that may have fallen or become loose.  Broken objects can be hazardous when stepped on and loosened object can later fall on people.  It is also a good idea to examine your foundation for cracks.
944523
In some areas of the world the tectonic plates press against each other with some amount of pressure. When the pressure grows too great, there is movement in one particular spot, which is then known as the epicenter. A small amount of movement is a small earthquake; a large amount equals a major earthquake.  It is a terrifying experience to be in a major earthquake -- that's why I moved away from Los Angeles.
370880
Extremely unlikely. I've never heard of any man made earthquakes.
962089
No.Tsunamis occur usally after there is an earthquake of a 7.0 maginitude under the ocean, for most tsunamis to occur the fault or the earthquake has to be under water and has to go up a reasonable mount of feet. Then it sends a wave which passes through a boey system and then that notifiys a the people on land.\nSince earthquakes are impossible to predict Tsunamis are too and that points also how often they occur. Not all earthquakes cause tsunamis, and if you heard of land one, it is most probaly it caused a underwater land slide or an out of water land slide which then crashes into the sea depending how big it is it will make anything to 1,000 foot wave.
1042537
While it is true that SC is considered a passive zone, it does not mean that we don't have earthquakes. Actually SC has a history of earthquakes though most of them are small when compared to those in California. In other words, they don't make the major network news reports. For instance, in February of last year we experienced a 2.9 (RS) quake in Columbia. Most of these small quakes occur in the Piedmont areas. In the last few years there have been several to the west of my location. For more info follow on the earthquake mentioned above follow this link... http://www.dnr.sc.gov/geology/images/Earthquake02-18-05.pdf\n\nAs far as knowing when a major earthquake will occur in SC, that is hard to tell. Earthquake prediction is a tricky business.\n\nThe greatest damage would most likely occur on the coastal plain due to liquefaction. That is where loose unconsolidated sediments/soil when shaken become like a liquid. In the case of a larger quake, this is a hazard not for folks just near the "fault line" but for any area on the coastal plain.\n\nThe link below is a map showing the major faults in SC.\nhttp://www.dnr.sc.gov/geology/images/Fault_Map_Generalized.gif\n\nThis link will take you to the USGS's latest earthquake occurrence map (w/in past 7 days). As you can see the west coast has been busy! http://earthquake.usgs.gov/eqcenter/recenteqsus/\n\nThe link below gives you the southeast's earthquakes in the past 6 months. As you can see, SC hasn't had any recently.\nhttp://folkworm.ceri.memphis.edu/recenteqs/
85265
Actually about two earth tremors are felt every year in Hong Kong. They are small, and less frequent than in other areas, however Hong Kong is NOT necessarily safe from earthquakes. \n\nThe nearest known plate boundary (of the Eurasian and Pacific plates) is about 600 km away, but there are still occasional midplate earthquakes that occur (seismologists do not know the origin of these). However, this does not mean that there is not some other fault nearby that has not revealed itself. Microplates near plate boundaries do exist, and sometimes these are surrounded by "locked" faults (because sufficient stress has not accumulated to overcome the resistance presented by asperities).  This can either mean that the chance of earthquakes is reduced, but it can also mean that if these asperities are overcome, the energy release can be substantial. \n\nThe Hong Kong government seismic observatory states that:\n\n"Several scientific studies carried out recently showed that in Hong Kong, the return period for an Intensity V (5) tremor would be 15 to 20 years and that for an Intensity VII (7) tremor would be 350 to 400 years." \n\nThe intensity scale is known as the Modified Mercalli Intensity Scale. An intensity of V corresponds to a magnitude of 4.3 to 4.8 on the Richter scale. An intensity of VII corresponds to a magnitude of 4.8 to 6.2 on the Richter scale.\n\nAccording to the official government of Hong Kong publication on earthquake hazards in Hong Kong:\n\n"Every year, about two earth tremors are felt in Hong Kong. To put this in context, studies into earthquake risk in Hong Kong carried out by the Geotechnical Engineering Office (GEO) classified the seismicity of Hong Kong and the adjoining Guangdong Province as "low to moderate". The earthquake hazard in Hong Kong is therefore considered to be very much lower than in areas such as Japan, Taiwan and the western USA which lie close to the earth's more seismically active zones along crustal plate boundaries. However, earthquake risk in Hong Kong cannot be regarded as negligible."