Grade 6

Question Answer
Stress A force that acts on rock to change its shape or volume
Tension Stress that stretches rock so that it becomes thinner in the middle
Compression Stress that squeezed rock until it folds or breaks
Shearing Stress that pushes masses of rock in opposite directions, in a sideways movement.
Normal fault A type of fault where the hanging wall slides downward; caused by tension in the crust
Hanging wall The block of rock that forms the upper half of a fault
Footwall The block of rock that forms the lower half of a fault
Reverse fault A type of fault where the hanging wall slides upward; caused by compression in the crust
Strike-Slip fault A type of fault in which rocks on either side move past each other sideways with little up or down motion
Anticline An upward fold in rock formed by compression of Earth's crust
Syncline A downward fold in rock formed by compression in Earth's crust
Plateau A large area of flat land elevated high above sea level and caused by compression
What 3 stresses work over millions of years to change the shape & volume of rock? Tension, Compression, and Shearing
Where do faults usually occur? Along pate boundaries, where the forces of plate motion push or pull the crust so much that the crust breaks.
What are the 3 main types of faults? Normal, Reverse, and Strike-Slip faults
What can the forces of plate movement change over millions of years? Flat plain into landforms such as anticlines and synclines, folded mountains, fault-block mountains, and plateaus
Earthquake The shaking that results from the movement of rock beneath Earth's surface
Focus The point beneath Earth's surface where rock breaks under stress and causes an earthquake
Epicenter The point on Earth's surface directly above an earthquake's focus
P wave A type of seismic wave that compresses and expands the ground
S wave A type of seismic wave that moves the ground up and down or side to side
Surface wave A type of seismic wave that forms when P waves and S waves reach Earth's surface
Mercalli scale A scale that rates earthquakes according to their intensity and how much damage they cause at a particulate place
Magnitude The measurement of an earthquake's strength based on seismic waves and movement along faults
Seismograph A device that records ground movements caused by seismic waves as they move through Earth
Moment magnitude scale A scale that rates earthquakes by estimating the total energy released by an earthquake
Richter scale A scale that rates an earthquake's magnitude based on the size of its seismic waves
What do seismic waves do? Carry energy from an earthquake away from the focus, through Earth's interior, and across the surface.
What are 3 commonly used ways of measuring earthquakes? Mercalli scale, Richter scale, and moment magnitude scale.
What do geologists use to locate an earthquake's epicenter? Seismic waves
Seismogram The record of an earthquake's seismic waves produced by a seismograph
Friction The force that opposes the motion of one surface as it moves across another surface
How do seismographs record an earthquake? During an earthquake, seismic waves cause the seismograph's drum to vibrate. But the suspended weight with the pen attached moves very little. Therefore, the pen stays in place and record the drum's vibrations.
How do geologists monitor faults? Geologists have developed instruments to measure changes in elevation, tilting of the land surface, and ground movements along faults.
What do seismographs and fault-monitoring devices provide? Data used to map faults and detect changes along faults. Geologists are also trying to use this data to develop a method of predicting earthquakes.
How are Fault-Block Mountains formed? 2 Normal Faults slip downwards
How do geologists locate the epicenter of an earthquake? Geologists look at the seismogram from the seismograph at three or more locations. Then the difference in arrival time is converted and they make a radius around each seismograph on a map where the three circles meet is where the epicenter is located