earthqu akes earthquake footage. epicenter the point on earth’s surface directly above where the...
Post on 02-Jan-2016
215 Views
Preview:
TRANSCRIPT
EarthquakesEarthquake
Footage
Epicenter• The point on Earth’s surface directly above where the
energy is released in an earthquake.• Focus = point where energy is released• Energy that reaches the surface is greatest at the
epicenter.
• Seismic Waves: Energy spreads outward in all directions as vibrations.
• Seismograph: Instrument that measures and records seismic waves.
• Seismogram: Seismic record, looks like jagged lines on paper.
Triangulation• Identifies the epicenter of an earthquake. • How?– Get records from 3 seismograph stations.– Plot circles on map from the records.– Find point where all 3 circles intersect.– That's the epicenter.
How to find the epicenter using triangulation
• Measuring time btwn arrival of P & S waves determines the distance btwn the seismograph & the epicenter.
Earthquake Waves• There are 3 types…
Primary (P) Waves Secondary (S) Waves Surface Waves
P and S waves explained
Primary (P) Waves• Move out from EQ focus• Travel fastest of the 3 waves• Move thru solid and liquid layers of Earth• PUSH and PULL rock, creating a back-and-forth
motion in the direction the wave is moving• Longitudinal wave
Secondary (S) Waves• Move out from EQ focus• Move slower than P waves• Only move thru solid rock• Move at right angles to P waves, causing rocks
to move UP and DOWN and SIDE to SIDE• Transverse wave
Surface Waves• Form when P and S waves reach the surface.• Can cause ground to shake, making rock sway
from SIDE to SIDE and ROLL like an ocean wave.
top related