earthquakes
DESCRIPTION
Earthquakes. Chapter 7 . Web Sites about Earthquakes. www.iris.edu http://earthquake.usgs.gov / For Fun http ://earthquake.usgs.gov/learn/facts.php. Information We Need from Earthquakes (EQ). EPICENTER (Latitude, Longitude) FOCUS ( Hypocenter ) (Depth of the EQ) - PowerPoint PPT PresentationTRANSCRIPT
Earthquakes
Chapter 7
Web Sites about Earthquakes
• www.iris.edu• http://earthquake.usgs.gov/
For Fun• http://earthquake.usgs.gov/learn/facts.php
Information We Need from Earthquakes (EQ)
• EPICENTER (Latitude, Longitude)• FOCUS ( Hypocenter ) (Depth of the EQ)• How Big it was ? How much Energy? (Mercalli intensity vs Richter Magnitude) • What Kind it was? What type of Fault• How Long it was ?
Epicenter vs. Hypocenter (Focus)
Mercalli Intensity Scale vs Richter Magnitude
• Mercalli Intensity is measured by means of the degree of damage to structures of human originBased on (Isoseismal Lines)
Richter Magnitude (Inhabited and Uninhabited regions)- Seismic wave amplitudes measured by a seismograph- He replace numbers by their logarithms. so instead of
using their amplitudes used the powers of the numbers
Mercalli vs Richter
Mercalli • Map of intensities with
isoseismal lines
Richter Magnitude• When a logarithmic scale
every time the magnitude goes up by 1 unit, the amplitude of the earthquake waves is increased by 10 times
• Example 4 to 5 ( 10 times )• 4 to 6 (100 times)• 4 to 7 (1000 times)
2010 Chile EQ vs Haiti EQChile Earthquake• www.usgs.gov
Magnitude scale
Earthquakes Waves
• Body Waves(P waves and S Waves) • Surface Waves ( Rayleigh and Love Waves)
P-S Waves
3 Components seismograph
Locating and Earthquake
• We need at least 3 station to estimate the epicenter of an earthquake !
• What do seismologist need arrival times for P and S waves
A simple formula is (S time – P time )x 8.2 = Distance in KM (Kilometers)
Example
Earthquakes in Plate Boundaries
• Transform California USGS today
• ConvergentExample Chile Earthquake (Nazca Plate subducting in South-America Plate)
• Divergent USGS website eq today
Wadatti-Benioff Zone
EQ prediction • Long-Term Prediction Probability • Short-term PredictionForeshocks
Earthquake Probability
How Rock and Soil Influence Earthquake Damage
• Mexico City Earthquake Example
• Liquefaction Soils behave like liquid,
Building Codes, Example Haiti Earthquake and Chile Earthquake
Tsunamis
• EQ summatra and Tsunami
Structure of Earth
Structure of Earth
• shadow Zone
