What is an earthquake?
An earthquake is a sudden shaking of the Earth's surface caused by rock breakage deep within the Earth. This is the result of stresses that have built up within the Earth's brittle crust.
There are different types of earthquake, depending on the part of the world in which they occur. Due to Australia's geological position, we are prone to intra-plate earthquakes which have a 'shallow focus'. These earthquakes are different and less predictable than the plate-margin type of earthquake which is common in areas like California, USA and Japan.
Measuring an earthquake
Magnitude
Energy released by (or magnitude of) an earthquake is calculated from a recording device called a seismograph, using a magnitude scale. The best known magnitude scale was developed by Richter. The most severe earthquakes so far, have not exceeded magnitude 9.5
Intensity
Another scale used to describe earthquakes is the modified mercalli (MM). It rates the amount of shaking felt at a particular place and damage caused, (or intensity) and uses Roman numerals. On this scale, I = detectable by instruments only, XII = total destruction.
Recent earthquakes in SA
http://minerals.dmitre.sa.gov.au/earthquakes/recent_earthquakes_in_sa
At GZ you will find a sign, You are welcome to log a "Found it" log when you message or email the answers for the following questions. any "Found it" logs without the answers being sent will be deleted.
What date was the Auburn earthquake and what was the Magnitude ?
What instrument is now used ? What is it replacing and what is it constantly "doing"?
Around GZ can you see any evidence from any local earthquake damage ? if so describe the damage.
If you were in a earthquake describe how you would measure the intensity of the earthquake.