Earthquakes

Earthquake the shaking of the Earth’s surface caused by movement along a fault. geological event, not related to weather.

1964 Alaskan Earthquake Magnitude 9.2

1964 Alaskan Earthquake. The stumps in the foreground are part of an ancient forest that was submerged below sea level and buried in prehistoric times.

1989 Loma Prieta Magnatude 6.9

Seismology study of earthquakes Seismograph

Fault a break in the Earth’s crust along which blocks of the crust slide past each other

San Andreas Fault located in California.

Richter Scale scale used to measure the magnitude of an earthquake the larger the number, the greater the magnitude and damage

Tectonic Plates giant pieces of Earth’s thin, outermost layer Tectonic Plate Boundaries – area where tectonics plate meet

World view with earthquake epicenters for magnitudes greater than 5 up to 1990.

Potential and Kinetic Energy Potential – stored in the rock because of tectonic forces, or stress. Kinetic – motion: released after enough pressure builds up in rock

Seismic Waves waves of energy that travel through the Earth, away from an earthquake in all directions

Effects - Landslides The sudden and rapid movement of a large amount of material down slope The plant and animal life is greatly affected through the loss of habitat (food, shelter, water). The area can re-grow over time.

1995 Landslide in La Conchita, California

Earthquake Lake was formed by the damming of Montana's Madison River as a result of a 1959 landslide caused by an earthquake.

Effects - Liquefaction Strong ground motion during an earthquake can cause soil like silt, sand, and gravel to act more like a dense fluid than a solid. The soil will act like a solid after the earthquake has stopped. Buildings are greatly affected.

Effects - Ground Shaking This causes collapsed buildings, cracks in buildings and roadways, change in environment, etc.

Aftershock earthquakes that follow the largest shock of an earthquake sequence. smaller and can continue over a period of weeks, months, or years. The larger the mainshock, the larger and more numerous the aftershocks, and the longer they will continue.

Effects - Tsunami Tidal wave During an earthquake, seismic waves can produce powerful ocean waves. When the wave enters shallow waters, the energy produces a tall wave that travels at high speed and moves far inland.

In deep water tsunamis are not large and pose no danger. They are very broad with horizontal wavelengths of hundreds of kilometers and surface heights much much smaller, about one meter. When a tsunami approaches the shore, the water depth decreases, the front of the wave slows down, the wave grows dramatically, and surges on land.

Seashores are ravaged twice: first by the large wave as it hits the shore and second when the water starts to recede and carries material back out to sea. Before and after pictures of Gleebruk Village in Indonesia after a tsunami hit.

Photos of Banda Aceh, Sumatra. Humans, wildlife, and plant life are all severely altered due to the flooding caused by a tsunami. Salt water kills and drowns plants. The previous shoreline disappeared. The habitat of the sea animals drastically changed due to the sediment in the water.

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