8.1
By an earthquake
earthquake under the ocean
Sept 29 2009
15.509 s, 172.034 w
An earthquake and tsunami struck Samoa and American Samoa on September 29, 2009. (September 30 in Australia time)
The Seismograph is used to measure the Magnitude of an earthquake.
An earthquake's magnitude is a measure of how strong it is
a Seismograph measure earthquake vibrations
In 2009, there was a big shake in Samoa called an earthquake. It caused the ground to move a lot and buildings to fall down. It made a big wave in the ocean that flooded some areas.
magnitudea measure of the amount of the energy released by earthquake . earthquake is measure through Ricthter scale that measure the magnitude of seismic waves that it has
to rate an earthquake
The Richter magnitude scale is used to measure the strength of an earthquake.