This document defines key terms related to earthquakes and seismic activity. It discusses earthquakes, faults, seismic waves including P and S waves, seismographs, seismograms, epicenters, foci, the gap hypothesis, seismic gaps, discontinuities, and seismic shadows. Seismic waves and how they travel through the Earth are defined. Instruments used to detect and record seismic waves like seismographs are also outlined.

2. • The study of earthquakes.

3. • A break in the Earth’s crust along which
blocks of the crust slide relative to one
another due to tectonic forces.

4. • The change in the shape of rock in
response to stress

5. • the sudden return of elastically deformed
rock to its original shape

6. • Waves of energy that travel through the
Earth.

7. pressure waves; the fastest type of
seismic waves
they can
travel through solids,
liquids, and gases.
Aka: primary waves

8. Shear waves.
Second fastest seismic
waves, can’t
travel through materials
that are completely liquid
aka: secondary waves

9. Made by breezy. :]

10. Seismograph:
an instrument located at or near the surface
of the Earth that records seismic waves.

11. Seismogram
• a tracing of earthquake motion created by
seismograph

12. Epicenter
• the point on the Earth’s surfaced directly
above an earthquake’s starting point

13. Focus
• The point inside the earth where an
earthquake begins.

14. Ch. 5 Sec. 3

15. Gap Hypothesis
• states that sections of active faults that
have had relatively few earthquakes are
likely to be the sites of strong earthquakes
in the future

16. seismic gap
• an area along a fault where relatively few
earthquakes have occurred

18. • A place within the Earth’s where the speed
of seismic waves increase sharply; marks
the boundary between the Earth’s crust
and mantle.

19. An area on the Earth’s surface where no direct
seismic waves from a particular earthquake can be
detected