8th Grade Earth Science CH 17A set 2

27 terms by HistoryFugue

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Earthquakes

P Waves, S Waves, L Waves

Three types of Earthquake Waves

P Waves

First waves to reach sensors -- can go anywhere

S Waves

Second waves to reach sensors -- Do not go through core

Core is liquid

Why do second waves probably not go through core

L Waves

Slowest and most destructive waves -- travel on surface

Calculated by finding difference between arrival of P and S waves

How do you find the distance to an earthquake

Sensor is farther from epicenter

What is indicated by a bigger interval between the arrival of the waves at the sensor

Triangulation

How is location found by sensors since one cannot pinpoint location

Computers

Today location is quickly found by using...

Depth of focus

What can be found by studying arrival times of all three waves

Amplitude and Wavelength

What do all waves have in common

Fault

Feature of earth's surface -- first thought to cause earthquakes, then thought to be result, now known to be feature caused by movement of tectonic plates

San Andreas Fault

most well-known fault -- type is strike-slip between the Pacific and North American tectonic plates

70 km or deeper

How deep does a quake need to be before it will not be felt -- thought to be quakes along fault line where one plate is sub ducting under other plates

save lives not property

Why are prediction techniques being developed -- also why are building materials and methods being improved

Fault lines

What is identified in earthquake-prone areas

Decades away yet

How long before scientists might be able to predict earthquakes

Where, When, Magnitude

What will be predicted

Pacific Rim or Ring of Fire

Circum-Pacific and Alpine Himalayan volcano belts are also known as

90%

How many earthquakes occur in Circum-Pacific or Alpine Himalayan

Volcanoes

What often trigger earthquakes

Volcanoes

what is sometimes preceded by an earthquake -- not known if the earthquake causes it though

Note places where lots occur and then see what gap between is and how often they occurred in the past

Today's prediction method

knowledge of deeper terrain (inner layers)

What is needed to understand why and when earthquakes will be happening

Being prepared

What is the next best line of defense if you aren't able to predict earthquakes

California

What state is often described as about to fall off into the ocean

No known reason

Multitude of sensors installed in California show that pressure sometimes builds up and then dissipates without an earthquake

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