Ch 8 Earthquakes

Fault

a crack or break in the earth's crust.

What does the Elastic Rebound Hypothesis state?

Earthquakes are produced by the rapid release of elastic energy stored in rocks within earth''s lithosphere. When the strength of the rocks present reach or exceed their breaking points, energy is released.

What is Liquefaction? Explain what could happen to populated regions.

Liquefaction is where loosely consolidated sediments are saturated with water. Land will turn into a liquid type material during moderate earthquakes.

Richter scale

out dates- only gives vague descriptions of effects felt at epicenter.

Moment Magnitude

most widely used scale. Gives accurate description of the effects felt near epicenter.

Can scientists predict when earthquakes are going to occur?

No only long-term estimates can be made based on "seismic gaps" in the areas history. Meaning an earthquake has not occurred in a location that has had frequent events in the past.

If the distance of an earthquake epicenter from three seismic stations is known, how can you find the exact location of the epicenter of the earthquake?

On a map draw a circle around each seismic station. The radius of each circle is the distance each station is from the epicenter, where all 3 circles intersect is the earthquake epicenter.

What are the 2 scales that are used to measure earthquakes? Which one is the most widely used and why?

Richter scale and Moment Magnitude. The moment magnitude is the most widely used scale.

What is a Tsunami? Describe what happens from start to finish?

(similar to a flash flood) A series of seismic sea waves produced from either an under-water landslide or the vertical displacement of the ocean floor during an earthquake. Tsunami can travel at speeds of 700mph in the open ocean. As they approach the shore, they slow and grow in size.

What are Aftershocks and Foreshocks

-Aftershocks are the movements that follow a major earthquake often produced smaller earthquakes -Foreshocks are small earthquakes that are often come before a major earthquake.

What are the differences between a body waves and surface waves?

-Body waves travel through earth's interior. -Surface waves are seismic waves that travel along earth's outer layer.

What are the properties of P waves, S waves, and Surface waves?

-P waves: "Primary" fastest velocity-always arrive 1st at seismic station travels in all materials solid, liquid, and gas. -S waves: "Secondary"-only travel through solids-2nd at seismic station -Surface Waves: "slowest"-only on surface/most destructive.

What is a Seismograph? What is a Seismogram?

-Seismographs are instruments that record earthquake waves. -Seismograms are the record made by a seismograph.

What are 3 factors that affect the designs of buildings in Earthquake prone areas?

1- Nature of material structure built upon (soil, foundation) 2- Building design and materials used 3- Duration and intensity of vibrations All 3 factors will contribute to wheather or not a structure will withstand an earthquake.

Explain 3 other types of dangers caused by earthquakes?

1- building/structure failure 2- landslides 3- fires 4- ground subsidence 5- basic services not available (power, water, gas)

What is an Earthquake? What are the differences between the focus and epicenter of the Earthquake?

An earthquake is the vibration of earth produced by the rapid release of energy. Slippage along a fault is generally the cause of all earthquakes. Focus is the point of earthquake origin below earth's surface directly below epicenter. Epicenter is the point of earthquake origin on the earth's surface.