[Juvena]

In my opinion, I don't think the UFO can create the earthquakes or UFO/aliens for that matter of a fact. I learn in school from my geography class that earthquakes are caused by fault line.

Why Do Earthquakes Happen?

Earthquakes are usually caused when rock underground suddenly breaks along a fault. This sudden release of energy causes the seismic waves that make the ground shake. When two blocks of rock or two plates are rubbing against each other, they stick a little. They don't just slide smoothly; the rocks catch on each other. The rocks are still pushing against each other, but not moving. After a while, the rocks break because of all the pressure that's built up. When the rocks break, the earthquake occurs. During the earthquake and afterward, the plates or blocks of rock start moving, and they continue to move until they get stuck again. The spot underground where the rock breaks is called the focus of the earthquake. The place right above the focus (on top of the ground) is called the epicenter of the earthquake.

http://www.geo.mtu.edu/UPSeis/why.html

1. What are earthquakes?

An earthquake is caused by a sudden slip on a fault. Stresses in the earth's outer layer push the sides of the fault together. Stress builds up and the rocks slips suddenly, releasing energy in waves that travel through the rock to cause the shaking that we feel during an earthquake.

2. What causes earthquakes?

According to the USGS, an earthquake occurs when plates grind and scrape against each other. In California there are 2 plates: the Pacific Plate and the North American Plate. The Pacific Plate consists of most of the Pacific Ocean floor and the California Coast line. The North American Plate comprises most the North American Continent and parts of the Atlantic Ocean floor. These primary boundary between these 2 plates is the San Andreas fault. The San Andreas fault is more than 650 miles long and extends to depths of at least 10 miles. Many other smaller faults like the Hayward (Northern California) and the San Jacinto (Southern California) branch from and join the San Andreas fault zone. The Pacific plate grinds northwestward past the North American Plate at a rate of about 2 inches per year. Parts of the San Andreas fault system adapt to this movement by constant "creep" resulting in many tiny shocks and a few moderate earth tremors. In other areas where creep is NOT constant, strain can build up for hundreds of years, producing great earthquakes when it finally releases.

A fault is a thin zone of crushed rock between two blocks of rock, and can be any length, from centimeters to thousands of kilometers. It is a fracture in the crust of the earth along which rocks on one side have moved relative to those on the other side. Most faults are the result of repeated displacements over a long period of time.

There are 3 different kinds of faults: (1) Normal, dip-slip fault. The fault plane of a normal fault dips away from the uplifted crustal block. Faulting occurs in response to extension.
(2) Reverse, dip-slip fault. The fault plane of a reverse fault dips beneath the uplifted crustal block. Faulting occurs in response to compression.
(3) Strike-slip fault. Crustal blocks slide past each other. The slip may be left lateral or right lateral. This example shows a left-lateral, strike-slip fault.

Earthquakes occur on 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, or at some angle to the surface of the earth. The slip direction can also be at any angle. Because of this, there are two different types of earthquake that can occur. The strike-slip earthquake occurs on an approximately vertical fault plane as the rock on one side of the fault slide horizontally past the other. The dip-slip earthquake happens when the fault is at an angle to the surface of the earth and the movement of the rock is up or down.

Surface rupture occurs when movement on a fault deep within the earth breaks through to the surface. Not all earthquakes result in surface rupture. Fault rupture almost always follows preexisting faults which are zones of weakness. Rupture may occur suddenly during an earthquake or slowly in the form of fault creep, which is the slow movement of faults in the earth's crust. Sudden displacements are more damaging to structures because they are accompanied by shaking.

There are several ways of finding a fault: (1) the earthquake left surface evidence, such as surface ruptures or fault scarps (cliffs made by EQs); (2) a large earthquake has broken the fault since we began instrumental recordings in 1932; and (3) the fault produces small earthquakes that we can record with the denser seimographic network established in the 1970s.

3. Can earthquakes be prevented?

No, but they can be mitigated. With proper planning now, you can avoid a lot of damage to your home, business and yourself when an earthquake strikes. To learn more about protecting your home or business from an earthquake, please see the home mitigation and business mitigation pages on our site.

http://www.crew.org/home/eqfacts.html