what to do

 OFFICIAL RESCUE TEAMS from the U.S. and other countries who have searched for trapped people in collapsed structures around the world, as well as emergency managers, researchers, and school safety advocates, all agree that “Drop, Cover, and Hold On” is the appropriate action to reduce injury and death during earthquakes. Methods like standing in a doorway, running outside, and “triangle of life” method are considered dangerous and are not recommended (see below).

the first erathquake that has happend

The world's largest earthquake with an instrumentally documented magnitude occurred on May 22, 1960 near Valdivia, in southern Chile. It was assigned a magnitude of 9.5 by the United States Geological Survey. It is referred to as the "Great Chilean Earthquake" and the "1960 Valdivia Earthquake

richter scale

Richter scale. The Richter magnitude scale was developed in 1935 by Charles F. Richter of the California Institute of Technology as a mathematical device to compare the size of earthquakes. The magnitude of an earthquakeis determined from the logarithm of the amplitude of waves recorded by seismographs.