Chapter 2 section 3

What is a seismograph?

A device that records ground movements caused by seismic waves as they move through Earth.

What are three ways geologists use seismographic data?

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

A seismograph records a strong earthquake and a weak earthquake. How would the seismograms for the two earthquakes compare?

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

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.

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 does a seismograph record seismic waves?

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.