An Earthquake

An earthquake (also known as a quake, tremor or temblor) is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time.
Earthquakes are measured using observations from seismometers. The moment magnitude is the most commonscale on which earthquakes larger than approximately 5 are reported for the entire globe. The more numerous earthquakes smaller than magnitude 5 reported by national seismological observatories are measured mostly on the local magnitude scale, also referred to as the Richter scale. These two scales are numerically similar over their range of validity. Magnitude 3 or lower earthquakes are mostlyalmost imperceptible or weak and magnitude 7 and over potentially cause serious damage over larger areas, depending on their depth. The largest earthquakes in historic times have been of magnitude slightly over 9, although there is no limit to the possible magnitude. The most recent large earthquake of magnitude 9.0 or larger was a 9.0 magnitude earthquake in Japan in 2011 (as of October 2012), andit was the largest Japanese earthquake since records began. Intensity of shaking is measured on the modified Mercalli scale. The shallower an earthquake, the more damage to structures it causes, all else being equal.
At the Earth's surface, earthquakes manifest themselves by shaking and sometimes displacement of the ground. When the epicenter of a large earthquake is located offshore, the seabedmay be displaced sufficiently to cause a tsunami. Earthquakes can also trigger landslides, and occasionally volcanic activity.
In its most general sense, the word earthquake is used to describe any seismic event — whether natural or caused by humans — that generates seismic waves. Earthquakes are caused mostly by rupture of geological faults, but also by other events such as volcanic activity,landslides, mine blasts, and nuclear tests. An earthquake's point of initial rupture is called its focus or hypocenter. The epicenter is the point at ground level directly above the hypocenter.

The Seven Steps to Earthquake Safety
Earthquakes and tsunamis are inevitable but the damage is not -- even in a very large earthquake. Preparing for the next damaging earthquake can help you and yourfamily to survive and recover.
The seven steps that follow include actions to keep you and your loved ones safe, reduce potential damage and recover quickly. These steps should also be followed in schools, workplaces, and other facilities. By following them, countless casualties can be avoided and millions of dollars saved.
Preparation is the key to surviving a disaster -- that much is clear --but where should you start? Start by talking -- talk to your family, friends, neighbors and co-workers about what you've learned in this handbook about earthquakes and tsunamis in Southern California. Then discussed what you have done to prepare and together plan your next steps.
Many people are overwhelmed by the mere prospect of a natural disaster and, as a result, don't prepare at all. Do notfall into that trap. You can start today by following these seven steps.
THE SEVEN STEPS TO EARTHQUAKE SAFETY:
PREPARE
before an earthquake or tsunami:
1. Secure your space
2. Create a plan
3. Prepare disaster kits
4. Strengthen your home

SURVIVE
during an earthquake:
5. Drop, cover, and hold on

RECOVER
after an earthquake or tsunami:
6. Check for injuries and damage
7. Followyour plan

STEP 1
Secure your space
1) Hang plants in lightweight pots with closed hooks, well secured to a joist or stud and far away from windows.
2) Install strong latches on kitchen cabinets.
3) Use flexible connections where gas lines meet appliances.
4) Remove or lock refrigerator wheels, secure to studs.
5) Secure valuable electronics items such as computers and televisions.
6) Keep...