By studying the earthquake, scientists learned that this ability of rock to stretch and store energy like a spring is what enables earthquakes to happen. Earthquakes are now explained by the elastic rebound theory, which goes something like this: Stress is applied to rock or to an existing fault over a period of time.
This usually happens at a plate boundary where two plates are moving in different directions, or in the same direction at different speeds. As the stress builds, strong rock or a locked fault a fault where the two sides are held together by friction deform elastically. Eventually, the stress overcomes the rock's strength or the fault's friction, and either the rock fractures or the fault slips. The energy that's released sets an earthquake in motion. The rock or fault rebounds, and the process may begin again.
See larger image. The force of the two sides of the San Andreas F ault sliding past each other bent railroad tracks between Los Gatos and Santa Cruz in Three basic fault types: strike-slip, normal, and reverse. How do I find the nearest fault to a property or specific location? Bay Area Earthquake Alliance For faults in California and the rest of the United States as well as the latest earthquakes use the Latest Earthquakes Map : click on the "gear" icon in the upper-right corner scroll down to Map Layers, and turn on U.
Faults mouse How do I find fault or hazard maps for California? An online map of faults that includes California is in the Faults section of the Earthquake Hazards Program website. What is the relationship between faults and earthquakes?
What happens to a fault when an earthquake occurs? Earthquakes occur on faults - strike-slip earthquakes occur on strike-slip faults, normal earthquakes occur on normal faults , and thrust earthquakes occur on thrust or reverse faults. When an earthquake occurs on one of these faults, the rock on one side of the fault slips with respect to the other. The fault surface can be vertical, horizontal, Filter Total Items: 7.
Year Published: 20 cool facts about the New Madrid Seismic Zone-Commemorating the bicentennial of the New Madrid earthquake sequence, December February [poster] This poster summarizes a few of the more significant facts about the series of large earthquakes that struck the New Madrid seismic zone of southeastern Missouri, northeastern Arkansas, and adjacent parts of Tennessee and Kentucky from December to February Williams, R.
View Citation. Year Published: Where's the San Andreas fault? Where's the San Andreas fault? Year Published: This dynamic earth: the story of plate tectonics In the early s, the emergence of the theory of plate tectonics started a revolution in the earth sciences. Kious, W. Jacquelyne; Tilling, Robert I. Year Published: Young faults Wallace, R. Year Published: Our changing continent Where were the land areas and oceans of the North American Continent one million years ago, compared to our present geography?
Geological Survey. Filter Total Items: 3. Date published: March 9, The U. Geological Survey has a new website that offers a virtual tour of the Hayward fault. Date published: December 4, Date published: November 7, Filter Total Items: 6.
List Grid. February 12, November 24, Seabed expression of the Queen Charlotte Fault in southeastern Alaska. A fault is a crack in the Earth's crust. Typically, faults are associated with, or form, the boundaries between Earth's tectonic plates.
In an active fault, the pieces of the Earth's crust along a fault move over time. The moving rocks can cause earthquakes. Inactive faults had movement along them at one time, but no longer move. The type of motion along a fault depends on the type of fault.
The main types of faults are described below. Normal dip-slip fault Normal faults happen in areas where the rocks are pulling apart tensile forces so that the rocky crust of an area is able to take up more space. The rock on one side of the fault is moved down relative to the rock on the other side of the fault. Normal faults will not make an overhanging rock ledge.
In a normal fault it is likely that you could walk on an exposed area of the fault. Reverse dip-slip fault Reverse faults happen in areas where the rocks are pushed together compression forces so that the rocky crust of an area must take up less space. The rock on one side of the fault is pushed up relative to rock on the other side. In a reverse fault the exposed area of the fault is often an overhang. Thus you could not walk on it. Thrust faults are a special type of reverse fault.
They happen when the fault angle is very low. Transform strike-slip faults The movement along a strike slip fault is horizontal with the block of rock on one side of the fault moving in one direction and the block of rock along the other side of the fault moving in the other direction. Strike slip faults do not make cliffs or fault scarps because the blocks of rock are not moving up or down relative to each other.
However, faults are usually more complex than these diagrams suggest. Often movement along a fault is not entirely of one variety. A fault may be some combination of strike slip and normal or reverse faulting.
0コメント