Earthquake Measurement Flashcards
What instruments are Earthquakes measured by?
Seismograph.
As the ground shakes, it causes the pen to move on the piece of paper.
How is a violent Earthquake distinguished on a seismograph?
The higher the peaks and troughs, the worse the Earthquake.
What does the Richter scale measure?
Earthquake magnitude.
Each year how many earthquakes are violent enough to cause damage and loss of life?
20-50.
What is the Richter scale?
Measures Earthquake magnitude from a scale of 0-9.
Earthquake measured at 6 is ten times more powerful that one measured at 5.
Higher on richter scale = less frequent Earthquake.
What is wrong which the Richter scale?
Does not indicate the effects on people.
Doesn’t provide accurate estimates on large magnitude Earthquakes.
What is the Mercalli Scale?
It assesses the degree of damage in built up areas and change in the natural environment.
Distinguished 12 degrees of severity based on direct observation and evaluation.
What is the Moment Magnitude Scale?
Based on total movement release of the Earthquake.
Moment is a product of distance a fault moved and force required to move it.
What is significant about the Moment Magnitude Scale?
Works over a wide range of Earthquake sized and is applicable globally.
Name 3 ways to measure eq?
Richter scale
Moment magnitude scale
Mercalli scale
1-3 on Richter scale
Only detected on seismographs - not actually felt
9-10 on Richter scale
Very rare and great
Ummense damange over large region
V. Moderate on mercalli scale ?
Felt by everyhone
Dishes / windows brownie
Unstable objects
Quite bad shaking
X.extreme mercalli
Well built structures destroyed
Foundations of buildings destroyed
Rails bent
When was the first seismic records done ?
1848
