The differences in travel time from the epicenter to the observatory are a measure of the distance and can be used to image both sources of quakes and structures within the Earth.
More thanpeople died. There also are striking connected belts of seismic activity, mainly along oceanic ridges —including those in the Arctic Oceanthe Atlantic Oceanand the western Indian Ocean —and along the rift valleys of East Africa.
A 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.
Pressure slowly starts to build up where the edges are stuck and, once the pressure gets strong enough, the plates will suddenly move causing an earthquake.
Examples are the earthquakes in Chile, ; Alaska, ; Sumatra,all in subduction zones.
Alaska is the most seismically active state and has more large earthquakes than California. Earthquakes associated with this type of energy release are called tectonic earthquakes. The aftermath may bring disease , lack of basic necessities, mental consequences such as panic attacks, depression to survivors,  and higher insurance premiums. Some people may not notice. For areas near large bodies of water, earthquake preparedness encompasses the possibility of a tsunami caused by a large quake. How do scientists measure the size of earthquakes? Tsunamis can also travel thousands of kilometers across open ocean and wreak destruction on far shores hours after the earthquake that generated them. The further you are from the storm, the longer it will take between the lightning and the thunder. Seismic Waves Shock waves from an earthquake that travel through the ground are called seismic waves. The boundary of tectonic plates along which failure occurs is called the fault plane. The longest earthquake ruptures on strike-slip faults, like the San Andreas Fault , , the North Anatolian Fault in Turkey and the Denali Fault in Alaska , are about half to one third as long as the lengths along subducting plate margins, and those along normal faults are even shorter.
Specific local geological, geomorphological, and geostructural features can induce high levels of shaking on the ground surface even from low-intensity earthquakes. How can scientists tell where the earthquake happened?
5 causes of earthquakes
Thrust faults are generated by the highest, strike slip by intermediate, and normal faults by the lowest stress levels. S waves and later arriving surface waves do main damage compared to P waves. There is one magnitude for each earthquake. Normal faults occur mainly in areas where the crust is being extended such as a divergent boundary. The earthquake will be the strongest at this point on the surface. Most of the earthquake's energy is used to power the earthquake fracture growth or is converted into heat generated by friction. How can scientists tell where the earthquake happened?
based on 7 review