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What is an Earthquake?

Earthquakes are the shaking, rumbling or sudden shock of the earth’s surface. They happen along "fault lines" within the earth’s crust. Earthquakes can be felt over large areas although they usually last less than one minute. Earthquakes cannot be predicted -- although scientists are working on it!

The intensity of an earthquake can be measured. One measurement is called the Richter scale. Earthquakes below 4.0 on the Richter scale usually do not cause damage, and earthquakes below 2.0 usually can’t be felt. Earthquakes over 5.0 on the scale can cause damage. A magnitude 6.0 earthquake is considered strong and a magnitude 7.0 is a major earthquake.

 

 

The Modified Mercalli Scale

Level Of Damage

The Richter Scale

1-4

Instrumental to Moderate

No damage.

</= 4.3

5

Rather Strong

Damage negligible. Small, unstable objects displaced or upset.

4.4 - 4.8

6

Strong

Damage slight. Windows, dishes, glassware broken. Furniture moved or overturned.

4.9 - 5.4

7

Very Strong

Damage slight-moderate in well-built structures; considerable in poorly-built structures.

5.5 - 6.1

8

Destructive

Structure damage considerable, particularly to poorly built structures. Frame houses moved. Trees damaged. Cracks in wet ground and steep slopes.

6.2 - 6.5

9

Ruinous

Structural damage severe; some will collapse. General damage to foundations. Serious damage to reservoirs. Underground pipes broken. Conspicuous cracks in ground; liquefaction.

6.6 - 6.9

10

Disastrous

Most masonry and frame structures/foundations destroyed. Some well-built wooden structures and bridges destroyed. Serious damage to dams, dikes, embankments. Sand and mud shifting on beaches and flat land.

7.0 - 7.3

11

Very Disastrous

Few or no masonry structures remain standing. Bridges destroyed. Broad fissures in ground. Underground pipelines completely out of service. Rails bent. Widespread earth slumps and landslides.

7.4 - 8.1

12

Catastrophic

Damage nearly total. Large rock masses displaces. Lines of sight and level distorted.

> 8.1


Source: FEMA.gov {{PD}}
 


How Earthquakes Effect

Communities ...

The recent earthquake in Japan (March 2011) registerd a 9.0 on the Richter Scale and was followed by a devestating tsunami killing mroe than 10,000 people.

New Zealand's earthquake (February 2011) measured 6.3-magnitude and caused extensive damage to the Canterbury Region of the South Island and caused the death of more than 170 people.

See How you can help the people
of Japan and New Zealand
on our

HOW TO HELP PAGE


What Can You Do ...

The most important thing to remember during an earthquake is to DROP, COVER and HOLD ON.

  • DROP to the floor
  • get under something for COVER
  • and HOLD ON during the shaking

 

READ: The Disaster Twins' - Shaky Vacation
{Source Fema.gov}

 

READ: A Native American Legend about Earthquakes
{Source Fema.gov}

Page created by:Eric R., Josue D., Endy P., Anthony A. , Bryan C. & CJ C. (USA)

Information source: http://www.fema.gov/hazard/earthquake/index.shtm