Download Earthquakes-1

yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

Reflection seismology wikipedia, lookup

2009–18 Oklahoma earthquake swarms wikipedia, lookup

Earthscope wikipedia, lookup

Earthquake prediction wikipedia, lookup

Seismic retrofit wikipedia, lookup

1880 Luzon earthquakes wikipedia, lookup

Earthquake wikipedia, lookup

Surface wave inversion wikipedia, lookup

Seismometer wikipedia, lookup

Earthquake casualty estimation wikipedia, lookup

- The movement of the ground, caused by
waves of energy released as rocks move along
Fault – a large fracture in rocks, from several
meters to many kilometers long, where rocks not
only crack but also move along either side of the
Types of Stresses; tension, compression, & shear
Types of Faults; Normal, Reverse, Strike-Slip
Earthquake Mechanics (cont.)
Epicenter – the point on Earth’s surface directly
above the earthquake’s focus
Focus – the point in Earth’s interior or where
movement releases energy to cause the
Seismic waves:
Waves of vibration caused by the energy
released during an earthquake.
• Types of waves produced: Surface and body
• Seismograph: is the instrument used to
detect, measure, and record seismic waves
produced by earthquakes.
• Magnitude - A measure of the strength of an
earthquake or strain energy released by it, as
determined by seismographic observations.
• Seismogram: the recording of an earthquake
made by a seismograph
Body Waves
P waves – Primary Wave:
compression & expansion - push-pull seismic waves
• sound waves (too low to be heard)
• fastest (~8 to 9 km/sec) depending on material
• first to be recorded at a seismograph
• causes rock particles to vibrate in the same
direction the wave is traveling
• denser the material, the faster the P-wave travels
Body Waves
S waves – Secondary Wave:
• shearing (lateral; side to side) seismic waves
• travels through solid only (3 to 5 km/sec) - NOT
liquid or gasses
• second to reach and be recorded at a
• causes the rock particles to vibrate at right angles
to the direction of travel
Surface Waves
Surface Waves – waves of energy, released
during an earthquake, that reach Earth’s
surface and travel outward from the epicenter
in all directions ON THE SURFACE ONLY
Travels only through solid
Surface Waves
L wave – Love wave:
• shearing (lateral; side to side) seismic waves
• speed is 2 to 6 km/sec
• has the greatest height of the ‘waves’
recorded on a seismogram
• has a horizontal (side to side) motion that is
perpendicular to the direction of travel
• causes the most destruction
• (named after A.E.H. Love, the English
mathematician who discovered it.)
Surface Waves
Rayleigh wave (Surface wave):
• Slowest of the waves 1 to 5 km/sec
• Most complex of earthquake waves; elliptical
motion at the Earth's surface.
• They are usually felt as a rolling or rocking
• In the case of major earthquakes, can be
seen as they approach
• Often the largest and most destructive, of the
wave types caused by an earthquake.
• Named after Lord Rayleigh, the English
physicist who predicted its existence.
Surface Waves
• Love waves – L-waves
• Rayleigh waves
Earthquake Machines
Seismograph – instrument that detects &
records earthquake seismic waves
Seismogram – the recording data sheet of
an earthquake made by a seismograph
Earthquake Intensity
• Modified Mercalli Scale – intensity scale
(modified for North American conditions);
composed of 12 increasing levels of intensity
that range from imperceptible shaking to
catastrophic destruction.
• Seismic moment - measures the earthquake’s
strength, or the energy released based the
amount of displacement along a fault.
Earthquake Intensity
• Richter Scale – measures the strength of an earthquake
– increase of one unit of magnitude (for
example, from 4.6 to 5.6) represents a 10-fold
increase in wave amplitude on a seismogram
– or approximately a 32-fold increase in the
energy released.
Therefore a magnitude 6.7 earthquake
releases over 900 times (32 times 32) the
energy of a 4.7 earthquake.
Creation of a Tsunami
Essential Questions -- Earthquakes
• Name and describe the 3 different seismic waves
• Explain how the structure of the earth’s interior
affects seismic waves
• Describe how seismographs are used to
determine the epicenter of an earthquake
• List the different scales used to measure the
magnitude and intensity of an earthquake
• Discuss the relationship between earthquakes and
• Identify the three types of stress and the resultant
features (faults/folds) associated with each.