# Earthquake Measurement

## Presentation on theme: "Earthquake Measurement"— Presentation transcript:

Earthquake Measurement
Chapter 8 Section 2

Locating Earthquakes Seismograph- an instrument that records vibrations in the ground and strength of an earthquake Seismogram- a tracing of earthquake motion that is created by a seismograph

Determining Time and Location of Earthquake
Start time is determined by noting the difference in arrival times of P waves and S waves. Seismograms is used to find the epicenter Epicenter- the point on the Earth’s surface directly above the earthquake’s starting point- focus Focus- the point along a fault at which the first motion of an earthquake occurs

S-P Time Method Used to find the epicenter Compare the results of
different seismograms of the same earthquake and find the common point

Measuring Earthquake Strength
Earthquake ground motion Magnitude increases by 1 unit, measured ground motion becomes 10 times larger Example: 0.5 on the Richter Scale produces 10x the ground motion as a 0.4. A 0.6 produces a 100x (10 x 10)the ground motion as a 0.4. Measuring Earthquake Strength

Measuring Earthquake Intensity
The degree in which it is felt by people and the damage it causes Modified Mercalli Intensity Scale to measure Ranked with Roman numerals I being the lowest ( not felt by most people) and XII being the highest (indicates total damage of an area)