What causes earthquakes?

Question

Of the following factors, which do you think is the most reliable predictor of earthquakes? Explain your answer.
1. recurrence interval
2. animal behavior
3. rock precursors

Answer 1

Dictionary of Geological Terms:

Earthquake – A sudden motion or trembling in the earth caused by the abrupt release od slowly accumulated strain.

Earth Structures 2nd Edition:

Earthquakes represent the sudden release of elastic strain energy that is stored in a rock, and can be generated when an intact rock ruptures, or when asperities on a preexisting fault snap off or suddenly plow. Rubbing two bricks while applying pressure is a good analogy of this process. The bricks move until the indentation of asperities once again anchors them. This start-stop behavior of faults is called stick-slip behavior. During the stick phase, stress builds up, while during the slip phase the fault moves and stress at the site of faulting drops. Typically, the stress drop is not complete, meaning that the differential stress does not decrease to zero.

Geoscientists have struggled for decades to delineate regions that have the potential to be seismic. This work involves the study of faults to determine if they are seismic or aseismic. But fault studies alone do not provide a complete image of seismicity, because not all earthquakes occur on recognized faults. Some represent the development of new faults, some represent slip on blind faults, and some represent non-fault-related seismicity.
The primary criterion for delineating a seismically active region comes from direct measurements of seismicity. The underlying idea is that places with a potential for earthquakes in the near future probably have suffered earthquakes in the past. Networks of seismographs record earthquakes and provide the data needed to pinpoint the focus of each earthquake; that is, the region in the Earth where the seismic energy was released. Maps of earthquake epicenters (the point on the Earth’s surface that lies directly above the focus) emphasize that most earthquakes occur along plate boundaries, but the dangerous earthquakes may also occur within plate interiors. With the exception of convergent-margin seismicity, most earthquakes occur at depths shallower than 15km, which defines the lower boundary of the brittle upper crust. Convergent-margin earthquakes occur along subduction slabs down to depths of about 650 km, defining the Wadati-Benioff zone.

Trying to predict an earthquake is a very complex and complicated task. By studying the geologic record, it is possible, at times, to understand the intervals between earthquakes in certain areas. There are, however, large numbers of areas that have not or cannot be studied do to location or depth. There are also large numbers of faults that are still unknown.

There are tests being made on tracking the strain build up in seismically active regions, to try to better understand the levels of differential stress before and after an earthquake in that region. There are also on going studies of the brittle deformation of specific rock types, and how much strain they can handle along with the amount of stored energy they may release when failure does occur.

Of the three choices you have, none of them are absolutely reliable.

1. recurrence interval
2. animal behavior
3. rock precursors

The absolute best answer would be a combination of 1 & 3. By studying the rock precursors, the strain the rocks are undergoing, and their response to that strain, along with the recurrence interval of seismic activity in that region, we may be able to predict the differential stress the rocks in the region can handle, and how long it will take for the point of failure to be reached.

Answer 2

An earthquake is what happens when two blocks of the earth suddenly slip past one another. The surface where they slip is called the fault or fault plane. The location below the earth’s surface where the earthquake starts is called the hypocenter, and the location directly above it on the surface of the earth is called the epicenter

Answer 3

An earthquake is the end results of a surprising launch of potential interior the Earth's crust that creates seismic waves. Earthquakes are recorded with a seismometer, additionally extensive-unfold as a seismograph. the 2nd value of an earthquake is conventionally reported, or the suitable and in particular out of date Richter value, with value 3 or decrease earthquakes being in particular imperceptible and value 7 inflicting severe harm over great aspects. intensity of shaking is measured on the changed Mercalli scale. on the Earth's floor, earthquakes ensue themselves by a shaking and now and back displacement of the floor. whilst a great earthquake epicenter is placed offshore, the seabed now and back suffers adequate displacement to reason a tsunami. The shaking in earthquakes may additionally set off landslides and on occasion volcanic pastime. In its maximum familiar experience, the be conscious earthquake is used to describe any seismic experience—no rely if a organic phenomenon or an experience led to by human beings—that generates seismic waves. Earthquakes are led to in particular by rupture of geological faults, extensive quantities of gas migration, in particular methane deep interior the earth, yet additionally by volcanic pastime, landslides, mine blasts, and nuclear experiments. An earthquake's factor of preliminary rupture is referred to as its concentration or hypocenter. The term epicenter potential the factor at floor point promptly above this .

Answer 4

Earth quakes are caused by the cooling effect from the center of the earth and gas pressures causing movement of the plates or hard surfaces of rock to move to release the pressure.

Answer 5

3 when the grounds shifts enough it will cause an earthquake..hope i helped