GEOL EXAM 3

Reverse Fault

A type of fault where the hanging wall moves upward relative to the footwall, typically associated with compressional forces in the Earth's crust.

Thrust fault

is a type of reverse fault where the angle of the fault plane is less than 45 degrees, causing the hanging wall to move up over the footwall.

Strike-Slip fault

A type of fault where two blocks of crust slide past each other horizontally, typically associated with lateral shear stress.

Dip-Slip fault

A type of fault where movement occurs vertically along the dip of the fault plane, which can be classified into normal and reverse faults depending on the direction of movement.

normal fault

is a type of dip-slip fault where the hanging wall moves down relative to the footwall, typically caused by extensional forces.

reverse/thrust fault

is a type of dip-slip fault where the hanging wall moves up relative to the footwall, typically caused by compressional forces.

Right Lateral Strike-Slip Fault

is a type of strike-slip fault where the opposite side of the fault moves to the right when viewed from either side, typically associated with horizontal shear stress.

Brittle behavior

refers to the tendency of materials to fracture or break under stress rather than deform plastically, often occurring in geological contexts when rocks are subjected to high stress.

Ductile behavior

refers to the ability of materials to undergo significant plastic deformation before rupture, allowing rocks to bend and flow under stress, commonly observed in geological processes at high temperatures and pressures.

P-waves

are primary waves that are the fastest seismic waves, traveling through solids and fluids by compressing and expanding the material in the direction of wave propagation.

S-waves

are secondary waves that follow P-waves, traveling only through solids and moving the ground perpendicular to the direction of wave propagation.

Love waves

are surface seismic waves that cause horizontal shearing of the ground, moving it side to side and typically causing more damage than P-waves and S-waves.

rayleigh waves

are surface seismic waves that produce both vertical and horizontal ground motion, often resulting in significant damage during an earthquake.

1st wave to arrive

is the P-wave, which travels fastest through all types of materials.

last waves to arrive

are the surface waves, specifically Love and Rayleigh waves, which arrive after P-waves and S-waves during an earthquake.

Most Destructive Seismic Wave

is the surface wave, particularly the Rayleigh wave, which typically causes the most damage due to its complex ground motion.

Seismogram

is a record produced by a seismograph that displays the seismic waves generated by an earthquake, showing their amplitude and frequency.

seismograph

is an instrument used to detect and record seismic waves produced by earthquakes, allowing for the analysis of their intensity and duration.

Hypocenter

the point within the Earth where an earthquake originates, specifically the location of the seismic energy release. Earthquake origin inside Earth.

Epicenter

the point on the Earth's surface directly above the hypocenter, where the seismic waves first reach the surface during an earthquake.

Determining the Epicenter

involves analyzing the arrival times of seismic waves at different monitoring stations to triangulate the location. 3 stations needed for triangulation

Where Do Earthquakes Occur?

Earthquakes primarily occur along tectonic plate boundaries, where stress builds up due to plate movements, leading to seismic activity. mostly at these (convergent, divergent, transform)

Shallow earthquakes

less than 70 km deep

deep earthquakes

greater than 300 km deep (subduction zone)

energy difference in magnitude

31.6^x, x= magnitude number

long term earthquake prediction (Seismic gap)

Area where earthquakes haven’t occurred in a while, likely to occur soon.

what causes tsunami?

underwater earthquakes, volcanic eruptions, or landslides

What causes rock deformation

stress (compression, tension, shear)

rock strain

change in shape or size of rock due to stress

tensile stress

causes stretching

compressional stress

causes shortening

joint fracture

natural fracture with no movement. rocks stay relatively in the same place no displacement.

Fault fracture

fracture with movement and displacement.

anticline fold

upward fold (arch)

syncline

downward fold (trough)

dome

circular upward

basin

circular downward

mass wasting

downward movement of material (rock, soil, debris)

landslide

a type of mass wasting, usually involving sliding.

factors affecting mass wasting

slope angle, water, vegetation, and earthquakes

factors controlling slope stability

slope angle, soil type, water content, vegetation

minimizing landslide hazards

grading, retaining walls, and drainage systems

causes of landslide hazards

heavy rain, earthquakes, volcanic activity, and human activity

base level

the lowest point a stream can erode (usually sea level)

gradient of a stream

the slope of the stream bed

dendritic; drainage network

tree like pattern (common)

radial drainage network type

radiates out from a central point

rectangular

right angle patterns (faults)

trellis

parallel streams with right angles (folded terrain)

Oxbow lake

a curved ____ formed when a meander is cut off from the river