Chapter 7 Flashcards
Which of the following measures an earthquake’s intensity based on the observed effects on people and structures?
Mercalli Scale
This scale measures the effects of earthquakes seen on the land surface and felt by humans. It measures from I-XII.
What is the purpose of a seismograph?
record vibrations produced during an earthquake
An instrument that detects and records vibrations and movements in the Earth, especially during an earthquake
What happens to a building during retrofitting?
adding steel or wood to reinforce the structure and connections
In what direction do rocks arch in an anticline?
in which the older rocks are in the center and the younger rocks are at
upward
A fold that arches upward, in which the older rocks are in the center and the younger rocks are at the outside.
What is the name for the region around the Pacific Ocean with high earthquake and volcanic activity?
pacific ring of fire
In what type of fault does compression cause rocks to bend and break?
reverse fault
also called a thrust fault; a fault in which the hanging wall moves up relative to the fault plane.
Which of the following is the place of origin for an earthquake?
focus
The point where rocks rupture during an earthquake.
Which of these help to make buildings safer during an earthquake?
placing large buildings on rollers so that they move with the ground
P-Wave
P-waves are body waves that are the first to arrive at a seismometer because they are the fastest. P-waves are longitudinal waves that travel through solids, liquids, and gases.
Which of the following hardly ever kills anyone in an earthquake?
ground shaking
Approximately what percentage of earthquakes occur at plate boundaries?
90%
Stress builds up on both sides of a fault. The rock deforms plastically, or bends, until the stress is too much. The rock on both sides of the fault snap back into their original position and release energy when they move. What is this called?
elastic rebound theory
The theory that earthquakes occur when rocks break and snap back to their original position after being deformed elastically until they cannot deform anymore.
In earthquake zones, gas lines and water pipes are built in a _____ design in order to take up motion and limit possible damage.
zig-zagged
How do rock particles move during the passage of a P wave through the rock?
P-waves are body waves that are the first to arrive at a seismometer because they are the fastest. P-waves are longitudinal waves that travel through solids, liquids, and gases.
back and forth parallel to the direction of wave travel
What type of fault is found at the San Andreas Fault in California?
strike-slip
A fault where rocks on either side of a nearly vertical fault plane move horizontally.
