EARTHQUAKES Flashcards
Give a description of earthquakes
Earthquakes have a spatial distribution in linear belts/clusters. They occur anywhere along plate boundaries and dd boundaries, 90% occur along plate boundaries
What are earthquakes?
A sudden movement of the earths crust
What is the depth of shallow, intermediate earthquakes and deep earthquakes?
Shallow (<70km depth)
Intermediate (70-300km)
Deep (>300)
Why do some earthquakes occur away from boundaries?
Reactivation of old fault lines
Longer pressure builds up…
…stronger the earthquake
Where do rocks obtain the strength?
Interlocking and cementation of grains or crystals of which they are built
What are earthquakes meander using?
A seismograph
What do high peaks and troughs show on a seismograph?
Worse or more violent earthquake
How many violent earthquakes does the world experience on average each year?
20-50
What is the magnitude of a earthquake measured on?
A Richter scale
What is the scale of the Richter scale?
0-9
On a Richter scale, and earthquake measured at 6 is how many times greater than a quake measured at 5?
Ten times more powerful
What instrument is used to measure the effects of the quake on people?
A Mercalli scale
How many degrees of severity are present on a Mercalli scale?
12 degrees of severity
What scale, abbreviated as Mw, is preferred for measuring earthquakes?
The moment magnitude scale
