Strike slip fault block diagram1/3/2024 ![]() ![]() Have students research examples of non-plate boundary faults. Explain that there is a broad range of faults based on type, linear extension, displacement, age, current or historical activity and location on contintental or oceanic crust. Explain that not all faults are associated with plate boundaries.What kind of fault is the San Andreas Fault? Is California likely to "fall off into the Pacific Ocean"? Why?.What kind of faults would you expect to find along the Mid-Atlantic Ridge? Why?.What kind of faults would you expect to find in the Himalaya Mountains? Why?.Strike-slip faults are often associated with transform (sliding) boundaries.Thrust faults are often associated with convergent (compressional) boundaries.Normal faults are often associated with divergent (tensional) boundaries.However, you can probably find all types of fault movement associated with each type of plate boundary. Explain that faults are often (but not always) found near plate boundaries and that each type of fault is frequently associated with specific types of plate movements.An excellent world physiographic map, showing the ocean floor, can be obtained from the National Geographic Society.Display the fault models in the classroom after the activity.Have students work in pairs or small groups.Time Neededġ or 2 Class periods Materials Needed (per group) Students will observe fault movements on a model of the earth's surface. Sites of greatest hazard are being identified, and designing structures that will withstand the effects of earthquakes. Scientists have begun to estimate the locations and likelihoods of future damaging earthquakes. Today we are challenging the assumption that earthquakes must present an uncontrollable and unforecastable hazard to life and property. If the earthquake occurs in a populated area, it may cause many deaths and injuries and extensive property damage. When the accumulated energy grows strong enough, the plates break free. At other times, the plates are locked together, unable to release the accumulating energy. For hundreds of millions of years, the forces of plate tectonics have shaped the Earth as the huge plates that form the Earth's surface slowly move over, under and past each other. An earthquake is a sudden movement of the Earth, caused by the abrupt release of strain that has accumulated over a long time. This fault is in a quarry in Rockingham County.One of the most frightening and destructive phenomena of nature is a severe earthquake and its terrible aftereffects. This small fault is a normal fault because the hanging wall has moved down relative to the footwall. Normal fault (Photograph by Stan Johnson) Note that the right side of the fault is the hanging wall which has moved down relative to the left side. Normal faults are caused by tensional stress, or stress that pulls rocks apart. If the hanging wall moves down relative to the footwall, the fault is a normal fault.The footwall is the part of the fault where your feet would be if you stood on the fault plane. The fault plane is the plane on which movement occurs. The above right diagram shows the block after faulting. In the above left diagram, the rock block is unfaulted, but contains a weakness. Faults also create environmental effects such as the movement of groundwater, and can cause hazards such as rock slides and earthquakes. Faults are classified according to which direction the rocks moved along the fault: normal faults, reverse faults, thrust faults, and strike-slip faults. ![]() Faults are fractures (cracks) in rocks along which movement has occurred. ![]()
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