Earthquakes: Magnitude and Intensity

magnitude: a measure of energy released by an earthquake

quantitative

as magnitude increases, the earthquake tends to:

affect a broader region

shake for longer (damage more buildings, cause more harm)

measures amplitude

amplitude: size of the waves on seismograph

logarithmic scale: each degree of magnitude is 10x bigger waves

equates to 50x more energy per degree of magnitude

not accurate for large, deep, or distant earthquakes

no longer used

the scale that’s now used

measures strain energy along rupture surface (energy released)

logarithmic scale: each degree of magnitude is 10x more energy released

more accurate than richter

most widely accepted and used by scientists

qualitative

what we feel in an earthquake

modified mercalli scale

“I'“ is felt by very few people or not at all to “X” which is total destruction

relates to ground motion’s effects on population and structures

rely on “felt” reports

people provide location and their own intensity rating

magnitude: a measure of energy released by an earthquake

quantitative

as magnitude increases, the earthquake tends to:

affect a broader region

shake for longer (damage more buildings, cause more harm)

measures amplitude

amplitude: size of the waves on seismograph

logarithmic scale: each degree of magnitude is 10x bigger waves

equates to 50x more energy per degree of magnitude

not accurate for large, deep, or distant earthquakes

no longer used

the scale that’s now used

measures strain energy along rupture surface (energy released)

logarithmic scale: each degree of magnitude is 10x more energy released

more accurate than richter

most widely accepted and used by scientists

qualitative

what we feel in an earthquake

modified mercalli scale

“I'“ is felt by very few people or not at all to “X” which is total destruction

relates to ground motion’s effects on population and structures

rely on “felt” reports

people provide location and their own intensity rating