1. EARTHQUAKE REPORTERS: Princess Danielle Matas Melvin Mantilla Charles Nomus

2. What is an earthquake?  Earthquakes occur with the passage of large seismic waves.  Earthquakes are the effects of a large seismic wave.  Seismic waves result from slip and rupture (breakage) of rocks along faults.  An earthquake (also known as a quake, tremor or temblor) is the result of a sudden release of energy in the Earth's crust that creates seismic waves.Earth'scrustseismic waves

3. Where Do Earthquakes Happen?

4. 1.Along Plate Edges Faults 2.Along Faults

5. Faults: Three types   Normal fault: Hanging wall moves down relative to the foot wall. Normal faults develop where the crust is under tension (is being pulled apart).   Reverse fault: Hanging wall moves up relative to the foot wall. A thrust fault is a reverse fault where movement occurs at a low angle. Reverse and thrust faults develop where the crust is undergoing compression.   Strike-slip (Transform faults): Block of crust on either side of the fault slip horizontally past one another. Right lateral: Right side of fault move towards you. Left lateral: Left side of fault moves towards you.

7. Earth quakes occur when a fault ruptures and stored energy is released as seismic waves. Quakes focus -> the point on the fault that first ruptures. Quakes epicenter -> the point on the Earth's surface directly above the focus. Most earthquakes occur in the upper 10 Km of the crust. It is here that rocks are cold enough to break in a brittle fashion and behave elasticly.

8. Elastic rebound theory: Rocks on either side of a fault bend as stress builds up. This stores energy in the rock. At some point, the rock ruptures (breaks) and the rocks on the two sides of the fault snap back to their original shale (elastic behavior). Energy is released as seismic waves.

9. Seismology   The study of earthquake waves, seismology, dates back almost 2000 years to the Chinese   Seismographs, instruments that record seismic waves Records the movement of Earth on a rotating drum, magnetic tape, or digital computer in relation to a stationary mass

10. Types of seismic waves: Body waves; Seismic waves that pass through the Earth. Primary waves: Compressional waves. Velocity5-8 km/sec - known as push-pull -fastest kind of seismic waves. It can push and pull the materials which can travel through solids and fluids when it moves through it. Secondary waves: Shear waves, Velocity 3.5-4.5 km/sec. - called as shear or secondary waves. -The wave moving through up and down or side-to-side -involves the rotation and shearing of the material. The movement of the wave can be transverse with moving particles and perpendicular to the ray.

12. Surface waves: Seismic waves traveling parallel to the Earth's surface. Surface waves: Seismic waves traveling parallel to the Earth's surface. Love waves: Shear waves parallel to Earth's surface.

13. Rayleigh waves: Rolling waves perpendicular to the Earth's surface.

14. Earthquakes primarily cause damage through: 1.Shaking -Shaking: Natural and man made factors can affect the amount of damage caused by ground shaking; Natural Factors: The effects of an earthquake can be amplified depending on the material upon which structures are built. This is known as ground amplification. Different materials will also transmit and enhance seismic waves of different frequencies. Natural Factors: The effects of an earthquake can be amplified depending on the material upon which structures are built. This is known as ground amplification. Different materials will also transmit and enhance seismic waves of different frequencies. Locating Earthquakes MaterialDegree of AmplificationSeismic wave frequency RockLittle amplificationHigher frequencies Sand and gravelModerate amplificationIntermediate frequencies MudModerate amplificationLow frequencies Low frequency seismic waves will cause most damage to large, tall structures High frequency seismic waves will cause most damage to smaller structures

15. 2.Liquefaction - A process where water saturated sand or silt loose their strength and ability to support structures when affected by shaking. A normally stable sediment or soil will behave like a liquid and structures will sink. Liquefaction allowed this sewer to float upward

16. Seiches Seiches  The rhythmic sloshing of water in lakes, reservoirs, and enclosed basins  Waves can weaken reservoir walls and cause destruction

17. Tsunamis, or seismic sea waves Destructive waves that are often inappropriately called “tidal waves” Result from vertical displacement along a fault located on the ocean floor or a large undersea landslide triggered by an earthquake

18. Can earthquakes be predicted?

19. Short-range predictions Goal is to provide a warning of the location and magnitude of a large earthquake within a narrow time frame.Goal is to provide a warning of the location and magnitude of a large earthquake within a narrow time frame. Research has concentrated on monitoring possible precursors – phenomena that precede a forthcoming earthquake such as measuring uplift, subsidence, and strain in the rocks. Research has concentrated on monitoring possible precursors – phenomena that precede a forthcoming earthquake such as measuring uplift, subsidence, and strain in the rocks.

20. forecasts Long-range forecasts Based on the premise that earthquakes are repetitive or cyclical Give the probability of a certain magnitude earthquake occurring on a time scale of 30 to 100 years, or more Using historical records or paleoseismology Are important because they provide information used to   develop the Uniform Building Code   Assist in land-use planning

21. Earthquakes are often accompanied by precursor events that may be able to provide short term warnings. Earthquakes are often accompanied by precursor events that may be able to provide short term warnings.   Fore shocks   Release of radon gas.   Ground deformation   Drop in water table.

22. ..END.. God bless!! ^__^