Earthquakes A Whole Lot of shakin going on

Earthquakes A Whole Lot of shakin’ going on!

What are Earthquakes and where do they occur? n n n Seismology is the study of earthquakes. Most earthquakes occur near the edges of tectonic plates due to their movement. Faults are breaks in the crust along which blocks of the crust slide relative to one another. They occur in many places, but are most common near the edges of tectonic plates.

Earthquakes Location of worldwide earthquakes

What Causes Earthquakes? n n n As the tectonic plates scrape against each other, stress builds up along faults near the plates’ edges. As a response to the stress, the rock in the plates bend or fold. Bending or folding, also called deformation is the change in the shape of rock in response to stress.

What Causes Earthquakes?

How Do Earthquakes Travel? n n The energy released travels in the form of seismic waves. Seismic waves are waves of energy that travel through the Earth. Waves that travel through the Earth’s interior are called primary waves (P waves). Waves that travel along the Earth’s surface are called surface waves (S waves).

Surface Waves n Surface waves move the ground up and down in circles as the wave travel along the surface.

Surface Waves n n n Move along the Earth’s surface Produces motion in the upper crust More destructive

How are Earthquakes Measured? Richter Scale

Typical Seismogram http: //isu. indstate. edu/jspeer/Earth&Sky/Earth. Ch 11. ppt

How do scientists calculate how far a location is from the epicenter of an earthquake? n n Scientists calculate the difference between arrival times of the P waves and S waves The further away an earthquake is, the greater the time between the arrival of the P waves and the S waves

Seismologist

Focus – point inside the Earth where an earthquake begins Epicenter – point on Earth’s surface above focus

Haiti January 2010 killed more than 200, 000 people and left 1. 5 million homeless.

Haiti

San Andreas Fault n The San Andreas Fault is the sliding boundary between the Pacific Plate and the North American Plate. It slices California in two

San Andreas Fault

San Andreas Fault

San Andreas n n n 01/09/1857 -Fort Tejon, 7. 9 magnitude 04/18/1906 - San Francisco, California, with a magnitude 7. 8, was one of the worst earthquake in California history. The earthquake killed over 3, 000 people and caused $524 million in property loss. The damage in San Francisco alone was over $20 million. Due to broken pipelines, water was shut off to the entire city. Many fires soon broke out throughout the city and caused major devastation as there was no water to put them out. This earthquake caused the lengthiest rupture of a fault in U. S. history. People as far as western Nevada and southern Oregon could feel the tremor. On 02/24/1892 - Imperial Valley, California with a magnitude of 7. 8, the third largest earthquake in California history occurred. This earthquake did quite a bit of damage, but caused no casualties. It destroyed many homes and cause rockslides. About 155 aftershocks were felt in the 12 hours following this quake.

San Andreas n n Last big earthquake in California was in 1999. 7. 1 magnitude In a remote location, so next to no damage. California is over due for the next big earthquake.

New Madrid Fault

New Madrid

New Madrid Fault http: //www. youtube. com/watch? v=Sjq. Vid. NX 23 o

New Madrid n http: //en. wikipedia. org/wiki/New_Ma drid_Seismic_Zone

Tsunamis http: //www. uwgb. edu/dutchs/Earth. SC-102 Visuals. Index. HTM

Formation of a tsunami http: //isu. indstate. edu/jspeer/Earth&Sky/Earth. Ch 11. ppt

Earthquakes Tidal waves or Tsunamis result when the low amplitude long wavelength w reach the shallow shoreline and begin to feel the bottom of the sea floor. Shortens the wavelength and increase the amplitude (height).

Japan 8. 9 -magnitude March 11, 2011 20, 000 lives lost

Japan

Japan

Ring of Fire n 90% of all earthquakes occur along the ring of fire.

Other quakes n http: //www. youtube. com/watch? v=8 6 OXNrq. V 4 -M