Chapter 19 Earthquakes Review

What are seismic gaps?

place along an active fault that has not experienced an earthquake in a long time

What is the focus?

point of initial fault rupture where the earthquake originates

What is the epicenter?

point on earth's surface, directly above the focus. Where most damage occurs

What are the 3 type of primary waves?

primary(p-wave), secondary(s-wave), surface (Rayleigh)

There is an earthquake in Haiti with a magnitude of 6 and one in Chile with a magnitude of 5. The earthquake in Haiti is how many times larger than the one in Chile?

10 times larger

How many seismometer stations are needed in order to locate an epicenter?

3

What are the 3 types of stress?

Compression, Tension, Shear

What happens with each type of stress?

Compression- decreases the volume of a material Tension- pulls the material apart Shear- causes a material to twist

What is the difference between elastic deformation and plastic deformation?

Elastic deformation causes to bend/stretch; proportional to stress. Plastic deformation permanent deformation caused by strain when stress exceeds a certain value

Which scale is used to measure intensity?

Modified Mercalli Scale

What mediums can each type of wave travel through?

P-wave- solid, liquid, gas s-wave- solid surface- can only travel on the surface

Name the 3 types of faults covered in class, describe each, and tell what type of boundary is typically involved.

Reverse- causes vertical movement upward along a fault plane; convergent Normal- causes vertical movement downward along a fault plane; divergent Strike-slip- causes horizontal movement along a fault plane; transform

If you look at a travel-time curve and notice that the S-wave arrived quickly after the P-wave, you can infer what about the distance from the epicenter?

The distance between the epicenter and the seismometer station are close.

What happens to P-waves when they reach the core?

They are refracted

What is strain?

deformation of materials in response to stress

When stress overcomes the strengths of the rocks, movement occurs along fractures in the rocks. The movement felt is known as

earthquakes

magnitude is a measure of what?

energy released during an earthquake

Earthquake forecasting is based on calculating the probability of an earthquake occurring. This possibility is based on which 2 factors?

history of earthquakes in the area and rate at which stress builds up in the rocks

What does the Richter scale measure?

mount of energy released during an earthquake (magnitude)

What is a seismic belt?

narrow belt-like areas with lots of earthquakes that separate large regions with little to no seismic activity

What led to the discovery that Earth's core must be at least partly liquid?

s-waves cannot travel through liquid. S-waves do not travel through the core so the core must be at least partially composed of liquid.

Which depth focus is responsible for causing the most amount of damage?

shallow depth focus

What is the difference between a seismometer and a seismogram?

seismometer is he instrument used to measure vertical/horizontal movement during the earthquake Seismogram is the record produced by the seismometer. Record of the types of seismic waves

The moment magnitude scale takes what into account?

size of the fault rupture, the rock's stiffness, amount of movement along the fault

The total force acting on crustal rocks per unit area is known as what?

stress

What is a shadow zone?

zone on earth's surface where p and s waves are not recorded due to the refraction of p-waves and the inability of the s-waves to travel through the core