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Anearthquake is a sudden shaking or disturbance of the earth's surface caused bymovements in the earth's outer layer. Energy, which naturally occurs within theearth, becomes disturbed or strained (creating a fault), and releases itself,causing the violent shaking that we define as an earthquake.
WHATIS A FAULT?
Afault is a layer in the earth's outer surface where rocks have moved due tohigh levels of energy. Once a fault slips, vibrations occur, and an earthquakeresults.
WHATIS AN AFTERSHOCK?
Aftershocksare as small earthquakes which come immediately after an earthquake.Aftershocks are felt as a series of shaking movements and most often accompanylarger earthquakes.
SEISMOLOGY:
Theterm "seismology" is Greek and literally defined as "toshake." The study of earthquakes is defined as seismology.SEISMOLOGISTS are scientists who research and study earthquakes and theirpatterns. By carefully analyzing the earth's surface before, during, and aftera quake, seismologists are able to see how the earth's energy moves. In recentyears, extensive study by seismologists has been able to pinpoint thedevastating effects of quakes and educate the public on how to prepare for theviolent ground shaking.
Suchwork has assisted in reducing property and structural damage, injury, and deatharound the world. SEISMOGRAPH is a scientific machine used to recordmovements within the earth's surface. RICHTER SCALE is not a machine, but amathematical formula which determines the strength of waves recorded on aseismograph. The resulting measurement defines the exact size of the quake.
WHEREDO EARTHQUAKES OCCUR??
Althoughit's possible for earthquakes to occur in any area of the world, seismologistshave concluded that most quakes are seen and felt in three specific areas:
1. PACIFICSEISMIC BELT:
Thisarea is found around the outer edges of the Pacific Ocean. Nearly 80-percent ofall large quakes occur in this region. The Pacific seismic belt measures fromChili to South America to the western region of the United States, includingthe southern tip of Alaska, the Aleutian Islands, Japan, New Guinea and NewZealand.
2. ALPIDE:
TheHimalayas, Mediterranean and the Atlantic make up the Alpide belt region.Approximately 18-percent of all earthquakes occur in this area.
Themid-atlantic ridge is the third most likely area where quakes occur, and coversthe region of from the north-south axis of the Atlantic to the Arctic Ocean tothe southern-most tip of Africa. In the United States, Alaska and Californiasee more earthquakes each year than any other State. Florida and North Dakotaare rarely affected by quakes.
HOWOFTEN DO EARTHQUAKES OCCUR?
1. SMALLQUAKES:
Earthquakestake place everyday. In fact, several hundred earthquakes are noted each dayaround the globe. Fortunately, most are too small to be felt. Each day,seismographs detect and record minor movements within the earth, most of whichare not felt and do not cause damage. Small quakes are technically known as"very minor," "minor" and "light" quakes,measuring between 3-4 on the Richter scale.
2. MODERATEQUAKES:
Moderateearthquakes happen approximately 15-20 times per year. Moderate quakes measure5-6 on the Richter scale and can cause millions of dollars in property damage.
3. LARGEQUAKES:
Largerquakes pass every few years and are classified as "strong,""major" or "great." Large earthquakes measure a 6 or aboveon the Richter scale. The largest-ever quake occurred in Chile on May 22, 1960.It measured 9.5 on the Richter scale.
EFFECTSOF AN EARTHQUAKE:
Thephysical effects of an earthquake are felt for 2-3 minutes. Within that shortamount of time, a tremendous amount of destruction can take place. Depending onthe type and strength of the quake, damage can be seen in soil, buildings,homes, pipelines, railways, bridges, and people. Earthquakes very often causefires, disease, contaminated water sources, Tsunami Waves, and infection.
PREPARINGFOR AN EARTHQUAKE:
Althoughearthquakes are not preventable, disaster control measures can be taken to helpreduce the effects of structural damage, injury and death.
1.Know where emergency supplies are located. Time is of the essence during andafter a quake, and acting quickly can save lives. Know where emergency suppliesare kept, including fire extinguishers, medications, First Aid Kits, tools,fresh drinking water, flashlights, and portable radios and phones.
2.Educate every family member as to what to do during a quake, and find a centrallocation of the house to meet following a quake, ensure safety of all.
3.Know where your water, electric and gas shut-off valves are located and how tooperate them.
DURINGAN EARTHQUAKE:
1. IFYOU ARE OUTSIDE when a quake occurs, run to the nearest open area, as faraway from buildings, trees, mountains, power lines, glass windows andstructures, and bridges as you can.
2. INSIDE, moveto an area where you can ground yourself and receive cover. Crawl under a heavydesk or table and hang on. Stay away from windows, doors, fireplaces, chimneys,washers and dryers, kitchens, and electrical areas.
3. IFYOU'RE IN YOUR CAR when a quake begins, stop driving and move your car tothe side of the road. Never stop under an overpass or bridge, and steer clearof trees, power lines, light poles, and signs. Remain in your car until thequake has finished, Shaking and the vibration at the surface of the earth.
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