Geology Chapter 4
Identify and describe S waves.
After P waves come secondary waves, or S waves. S waves are seismic waves that can vibrate from side to side or up and down. Their vibrations are at an angle of 90 degrees to the direction that they travel. When S waves reach the surface, they shake structures violently. While P waves travel through both solids and liquids, S waves cannot move through liquids.
Hours, days, months is how long it can be.
Aftershock
Shearing looks like a transform boundary and is a strike slip fault(San Andreas) Tension looks like a divergent boundary and is a normal fault Compression looks like a convergent boundary that is a reverse fault.
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The Modified Mercalli is useful in regions where there aren't many instruments to measure an Earthquakes strength.
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The Richter Scale it;s good for small and new-by earthquakes
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The Moment Magnitude Scale is used today
6.0(32) 70.(32x32=1024 stronger and so on)
What is the Richter Scale?
An earthquake's magnitude is a single number that geologists assign to an earthquake based on the earthquake's size. There are many magnitude scales. These scales are based on the earliest magnitude scale, called the Richter scale. Magnitude scales like the Richter scale rate the magnitude of small earthquakes based on the size of the earthquake's based on the size of the earthquake's waves as recorded by seismographs. The magnitudes take into account that seismic waves get smaller the farther a seismograph is from an earthquake.
A fold in rock that bends upward into an arch.
Anticline
The stress force that squeezes rock until it folds or breaks is called ______________.
Compression
Motions that add stress to rocks.
Deformation
-Shaking, moving, and trembling -Happens because rock move beneath Earth's surface.
Earthquake
The point on Earth's surface directly above an earthquake's focus.
Epicenter
Breaks in Earth's crust Move a lot Found at plate boundaries
Faults
The point beneath Earth's surface where rock first breaks under stress and causes an earthquake.
Focus
Bends in rock that form when compression shortens and thickens Earth's crust.
Folds
How do folds form?
Folds are bends in rock that form when compression shortens and thickens Earth's crust. A fold can be a few centimeters across or hundreds of kilometers wide.
What is the Moment Magnitude Scale?
Geologists use the moment magnitude scale to rate the total energy an earthquake releases. News reports may mention the Richter scale, but the number quoted is almost always an earthquake's moment magnitude. To assign a magnitude to an earthquake, geologists use data from seismographs and other sources. The data allow geologists to estimate how much energy the earthquake releases.
What land formations are the result of anticline and syncline?
Geologists use the terms anticline and syncline to describe upward and downward fold in rock. A fold in rock that bends upward into an arch is an anticline. A fold in rock that bends downward to form a V shape is a syncline. Anticlines and synclines are found in many places where compression forces have folded the crust. The central Appalachian Mountains in Pennsylvania are folded mountains made up of anticlines and synclines.
What land formations are the result of Fault-block mountains?
If you traveled by car from Salt Lake City to Los Angeles, you would cross the Great Basin.This region contains many mountains form from tension in Earth's crust that causes faulting. Such mountains are called fault-bock mountains. Fault-block mountains form where two plates move away from each other, tension forces create many normal faults. Suppose two normal faults cause valleys to drop own on either side of a block of rock. As the hanging wall. of each normal fault slips downward, the block in between now stands above the surrounding valleys, forming a fault-block mountain.
An earthquake's ___________ is a single number that geologists assign to an earthquake based on the earthquake's size.
Magnitude
Rates amount of shaking form an earthquake.
Modified Mercalli Scale
Geologists use the _______________________ to rate the total energy an earthquake releases.
Moment Magnitude Scale
A type of fault where the hanging wall slides downward; caused by tension in the crust.
Normal fault
Identify and describe compression.
One plate pushing against another plate can squeeze rock like a giant trash compactor. The stress force that squeezes rock until it folds or breaks is called compression. Compression occurs where two plates come together.
Seismic waves that compress and expand the ground like an accordion.
P waves
A large landform that has high elevation and a more or less level surface.
Plateau
A type of fault where the hanging wall slides upward; caused by compression in the crust.
Reverse fault
A scale that rates an earthquake's magnitude based on the size of its seismic waves.
Richter scale
Identify and describe tension.
Rock in the crust can be stretched so that it becomes thinner in the middle. This process can make rock seem to act like a piece of warm bubble gum. The stress force that pulls on the crust and thins rock in the middle is called tension. Tension occurs where two plates pull apart.
Seismic waves that can vibrate from side to side or up and down.
S waves
Vibrations that travel through Earth carrying the energy released during an earthquake.
Seismic Waves
Which direction do seismic waves travel from the focus?
Seismic waves carry energy from the earthquake's focus. This energy travels through Earth's interior and across Earth's surface. I think they would move outward.
An instrument that records and measures an earthquake's seismic waves.
Seismograph
Stress that pushes a mass of rock in two opposite directions is called ________________.
Shearing
-Pressure(force) -Change in shape or volume
Stress
A force that acts on rock to change its shape or volume.
Stress
Identify and describe shearing.
Stress that pushes a mass of rock in two opposite directions is called shearing. Shearing can cause rock to break and slip apart or to change its shape. Shearing occurs where two plates slip past each other.
A type of fault in which rocks on either side move past each other sideways with little up or down motion.
Strike-slip fault
What are three types of faults?
Strike-slip, normal, and reverse fault.
Move more slowly than P and S waves, but they can produce severe ground movements.
Surface waves
A fold in rock that bends downward to form a V shape.
Syncline
The stress force that pulls on the crust and thins rock in the middle is called _________________.
Tension
What are three types of of stress on rock?
Tension, compression, and shearing.
What is the Modified Mercalli Scale?
The Modified Mercalli Scale rates the amount of shaking from an earthquake. The shaking is rated by people's observations, without the use of any instruments. This scale is useful in regions where there aren't many instruments to measure an earthquake's strength.
Identify and describe normal fault.
The Rio Grande River flows through a wide valley in New Mexico. Here, tension has pulled apart by tension in Earth's crust, forming the valley. Where rock is pulled apart by tension in Earth's crust, normal faults form. In a normal fault, the fault cuts through rock at an angle, so one block of rock sits over the fault, while the other block lies under the fault. The block of rock that sits over the fault is called the hanging wall. The rock that lies under the fault is called the footwall. When movement occurs along a normal fault, the hanging wall slips downward. Normal faults to occur where two plates diverge, or pull apart.
What land formations are the result of Fold Mountains?
The collision of two plates can cause compression and folding of the crust over a wide area. Folding produced some of the world's largest mountain ranges. The Himalayas in Asia and the Alps in Europe formed when pieces of the crust folded during the collision of two plates. These mountains formed over millions of years.
Identify and describe P waves.
The first waves to arrive are primary waves, or P waves. P waves are seismic waves that compress and expand the ground like an accordion. Like the other types of seismic waves, P waves can damage building.
What is the key difference between the footwall and the hanging wall? What is the exception to this difference?
The foot wall is the block of rock that lies under the fault. The hanging wall is the block of rock that sits over the fault. In the normal fault, the hanging wall lies under the fault and the footwall sits on top the fault. In the reverse fault, the hanging wall lies under the fault and the footwall sits on top the fault.
Identify and describe strike-slip fault.
The hilly plains in southern California are spilt by the San Andreas fault. Here, shearing has produced a strike-slip fault. Ina strike-slip fault the rocks on either side of the fault slip past each other sideways, with little up or down motion. A strike-slip fault that forms the boundary between two plates is called a transform boundary. The San Andreas fault is an example of a transform boundary.
Identify and describe reverse fault.
The northern Rocky Mountains rise high above the western United States and Canada. These mountains were gradually lifted up over time by movement along reverse faults. A reverse fault has the same structure as a normal fault, but the blocks move in the reverse direction. That is, the hanging wall moves up and the footwall moves down. Reverse faults form where compression pushes the rock of the crust together.
What does a rock look like under no stress at all?
The rock looks normal, mostly flat, hard, and stiff.
H2o displacement by earthquake (seismic wave that form larger waves)
Tsunami
Identify and describe Surface waves.
When P and S waves reach the surface, some of them become surface waves. Surface waves move more slowly than P and S waves, but they can produce severe ground movements. These waves produce movement that is similar to waves in the water, where's the water's particles move in a pattern that is almost circular. Surface waves can make the ground roll like ocean waves.
