Earthquakes Flashcards
Why do earthquakes occur?
Convection currents in the mantle builds up pressure which is released
What is the focus?
The point within the earths crust from which the earthquake begins
What is the epicentre?
The point above the focus on the surface where the earthquake is most strongly felt
What are the waves called that radiate out from the epicentre?
Shock waves
What is used to record the strength of an earthquake? (Extent)
Seismograph
What is a Richter scale?
Measurement of the strength/ magnitude of earthquake
Logarithmic
Numerical
10=complete destruction
What is a mercallis scale?
Measure of effects using sight
Roman numerals
Words and pictures to describe
What is an earthquake?
A build up and release of pressure inside the earth that mainly occurs at plate boundaries but can occur anywhere e.g. Fault lines
Why do earthquakes occur at conservative boundaries?
Tension builds and as slide past each other and get stuck
What do earthquakes occur at destructive plate margins?
Tension builds up when one plate gets stuck as it’s moving past the other into the mantle
Why do earthquakes occur at constructive plate boundaries?
Tension builds along cracks within the plates as they move apart
What are the Richter and mercallis scale measured on?
Richter- 1-10 (seismograph)
Mercallis- 1-12
How does a seismograph work?
A seismometer detects the vibrations caused by an earthquake and plots these vibrations on a seismograph
