This document defines key terms related to earthquakes and seismic waves. It explains that earthquakes are caused by a sudden release of energy along fault lines in the earth. The focus is the location within the earth where the earthquake starts, while the epicenter is the point on the surface directly above the focus. There are three main types of seismic waves: P-waves which move in the direction of travel, S-waves which move sideways, and surface waves which cause the most damage. The timing and speed of P and S waves detected by seismic stations can be used to locate the epicenter of an earthquake.

1. EARTHQUAKES

2. A movement or trembling of the ground that is
caused by a sudden release of energy when
rocks move suddenly along a fault line
WHAT ARE EARTHQUAKES:

3.  The location within the Earth along a fault at
which the first motion of an Earthquake
occurs
FOCUS:

4.  The point on the Earth’s surface above the
focus
EPICENTER:

5.  Primary Wave
 Motion is back and forth in the direction of
travel (Compression wave)
 Fastest of the waves and can travel through
all phases of matter
TYPES OF SEISMIC WAVES:
A. P-WAVE

6.  Secondary Wave
 Motion is side to side compared to direction
of travel (Shear Waves)
 Second fastest and can only travel through
solids
TYPES OF SEISMIC WAVES:
B. S-WAVE:

7. A seismic wave that travels along the surface
and has a stronger effect; converted P and S
wave, causes the most damage
TYPES OF SEISMIC WAVES:
C. SURFACE WAVES:

8. Various densities and
phases are shown by wave
deflection
 S waves blocked by liquid
outer core
HOW DID WAVES LEAD TO OUR
KNOWLEDGE OF EARTH’S INTERIOR?

9.  The longer the time difference between the
arrival of the P and S waves, the farther from
the epicenter
HOW DO YOU DETERMINE THE LOCATION
OF AN EARTHQUAKE?

10.  Use the distance from three seismic stations
as radii for three circles to determine
epicenter location
HOW DO YOU DETERMINE THE LOCATION
OF AN EARTHQUAKE?