Science Chapter 5, lesson 3

What are three ways geologists use seismographic data?

Mapping faults, monitoring changes along faults and trying to predict earthquakes.

How would the seismograms of a strong earthquake and a weak earthquake compare?

The bigger earthquake would show bigger, more jagged lines on the seismogram and the weaker quake would have shorter lines.

Friction

The force that opposes one surface as it moves across another surface.

Seismogram

The record of an earthquake's seismic waves produced by a seismograph.

What changes does each instrument measure?

Tiltmeter measures vertical movement. Creep meter measures horizontal movement. Laser-ranging device measures horizontal movements. GPS satellite measures vertical and horizontal movements.

What four instruments are used to monitor faults?

Tiltmeters, creep meters, laser-ranging device, and GPS satellite.

How do geologists monitor faults?

To monitor faults, geologists have developed instruments to measure changes in elevation.

Why is it difficult to predict earthquakes?

Because earthquakes are all different and do not occur the same way every time.

What could an increasing tilt in the land surface indicate?

It indicates a build up of stress in rock and could lead to an earthquake.

How are seismographic data used?

It is used to map faults and detect changes along faults. Geologists are also trying to use this data to develop a method for predicting earthquakes.

How does a creep meter work?

It uses a wire stretched across a fault to measure horizontal movement of the ground.

How do seismographs work?

Seismic waves cause a seismograph's drum to vibrate. But the suspended weight with the pen attached moves very little. Therefore, the pen stays in place and the records the drums vibrations.

How do geologists use seismographic data to make maps of faults?

Seismographs detect the reflected seismic waves and geologists use this data to map the length and depth of the fault.

Why do geologists collect data on friction along the sides of faults?

So they can try to predict the probability of a large earthquake.