QUIZ 1. What is Seismology? 2. What is the name of the record produced by

a seismometer?3. T or F Seismic waves proves the EARTH’s

outer core is liquid.4. What is the name of the first wave generated

by an earthquake?BONUS 5. Name the point on Earth’s surface that is

directly above the focus of the earthquake.

ANSWERS 1.Seismology: is the scientific

study of earthquakes and the propagation of vibrations through Earth

2.Seismograms3.TRUE 4.P WAVE BONUS 1. EPICENTER

How are EQ’s Described?

MAGNITUDE &

INTENSITY

Magnitude

• Magnitude is the measurement of the energy released during an EQ • Measured on the Richter Scale

Richter scale measures total amount of energy released by an earthquake

Intensity • Intensity is a measure of damage caused by an EQ

noted by observers during & after EQ

• Measured by the Modified Mercalli Scale

Locating EQ’s

Seismologists analyze data from seismograms to

Locate the Epicenter &

Time of EQ occurrence

Locating an Epicenter• Three

seismograph stations are needed to locate the epicenter of an earthquake

• A circle where the radius equals the distance to the epicenter is drawn

• The intersection of the circles locates the epicenter

Time of an EQ

• The gap in arrival time between waves provides the info about the distance to the epicenter.

• Time of EQ occurrence is determined by the exact time of wave arrival at the seismic station and applying it to the travel time curve

Travel-Time Curves

Seismic Belts Locations of EQ correspond closely with tectonic

plate boundaries

• About 80% of all earthquakes occur in the circum-Pacific belt

• About 15% occur in the Mediterranean-Asiatic belt

• The remaining 5% occur in the interiors of plates and on spreading ridge centers

• More than 150,000 quakes strong enough to be felt are recorded each year

ANY QUESTIONS?