3. Types of earthquake
Tectonic earthquakes
these occur when rocks in the
earth’s crust break due to geological
forces created by the movement of
tectonic plates.
Volcanic earthquakes
occur in conjunction with
volcanic activity.
4. Collapse earthquakes
are small earthquakes in
underground caverns and mines.
Explosion earthquakes
result from the explosion of
nuclear and chemical devices.
5. Focus and Epicenter
• FOCUS = place deep within the
Earth and along the fault where
rupture occurs
• EPICENTER = geographic point
on surface directly above focus
6.
7. Seismologists are scientists that study
earthquakes and seismic waves.
Seismic Waves – shock waves of
energy sent out as the crust shakes
Seismograph is the instrument they use
to obtain a record of seismic waves from all
over the world.
8.
9. Seismograms zigzag line made
by a seismograph.
• Amplitude of seismic waves (how much
rock moves or vibrates)
• Distance to the epicenter
• Earthquake direction
10.
11. Types of seismic waves
1. Body waves -- travel through
interior
2. Surface waves -- travel on
surface of earth
Slowest
12. 2 kinds of Body Waves
1.P-waves (Primary waves)
Fastest of the three waves and the first
detected by seismographs.
• Can travel through Earth’s interior in less than
an hour
• Pass through solids & liquids
• As they pass through the liquid of the outer core
they change directions
• As they return to Earth’s surface they cause
back-and-forth motions of rock
13. 2. S-waves (Secondary waves)
• Travel slightly slower than P waves
• When they reach Earth’s surface they
cause it to move up and down
• They can travel ONLY through solids
• When they pass through the mantle to
the liquid core they lose their energy
and do not return to the surface
14. 2 types of Surface waves
1.Love waves– that move like S
waves but only horizontally.
2.Rayleigh waves– that move
both horizontally and vertically
in a vertical plane pointed in the
direction of travel
17. LIQUEFACTION
• Results in a loss of soil strength & the ability of the soil to
support weight
when a solid (sand and soil) becomes saturated
with water and acts like a heavy liquid
21. • Foreshocks are small bursts of shaking
that may precede a large earthquake.
• Aftershocks are small tremors that
follow an earthquake, lasting for hours or even
days after the earthquake.
22. EARTHQUAKE INTENSITY
Modified Mercalli scale= measurement of damage to structures
• From I to XII
(Roman numerals)
• Descriptive, changes with
distance from epicenter
• Can change from location
to location
What you need:
• Your senses!
measures damage to man-made structures at
certain location
25. EARTHQUAKE INTENSITY
Modified Mercalli scale= measurement of damage
to structures
• From I to XII
(Roman numerals)
• Descriptive, changes with
distance from epicenter
• Can change from location
to location
What you need:
• Your senses!
measures damage to man-made structures at
certain location
26.
27. EARTHQUAKE MAGNITUDE
measures the size of seismic waves
the energy released by the earthquake
Richter scale=measurement of energy
released based upon wave amplitude (size of
vibration)
• <2 to ~10
• Amplitude of wave goes up
by 10 (Logarithmic scale)
30. VOLCANOES
• An opening in Earth’s surface through
which melted rock, hot gases, rock
fragments, and ash burst forth, or erupt
• Volcano – comes from the ancient Roman
god of fire, Vulcan
• Start 37 – 100 miles below surface
• Rock melts and is called Magma
