Earthquakes

earthquake

A sudden and violent shaking of the ground, often caused by the movement of tectonic plates or volcanic activity. Earthquakes can result in significant damage to structures and landscapes.

epicenter

The point on the Earth's surface directly above the origin of an earthquake, where seismic waves are first felt.

seismic waves

Waves of energy that travel through the Earth's layers, generated by the sudden release of energy during an earthquake or explosion. They include primary waves (P-waves) and secondary waves (S-waves).

different types of seismic waves

P waves. S waves, Surface waves

p waves

The fastest type of seismic wave, which compresses and expands the material through which they travel. P-waves can move through solids, liquids, and gases.

s waves

Seismic waves that are slower than P waves and move in a side-to-side motion. S waves can only travel through solids.

surface waves

Seismic waves that travel along the Earth's surface, causing the most damage during an earthquake. They move the ground up and down or side to side.

fault

the rock the slips or breaks, crack in crust, Earthquake has to happen on it

focus

area beneath surface where rock under stress begins to break or moves

plate movement

causes earthquake

two ways of measuring seismic waves

amount of damage made/shaking that is felt or magnitude(size) of earthquake

seismograph

instrument that records and measures earthquake’s seismic waves

Modified Mercalli Scale

rates the amount of shaking from the earthquake, based on observations

Richter scale

measures the magnitude of earthquakes

magnitude

single number geologists assign to earthquakes based on its size

smaller

seismic waves get ________ the farther a seismograph is from the earthquake

longitudinal waves

compression, p-waves

transverse waves

wave motion, s-waves

Moment Magnitude Scale

rate total energy earthquake produces

to find epicenter

scientists use seismic waves

stress

force that acts on rock to change shape or volume

energy

stress adds it to rock which is stored for later until it breaks

tension

stress force that pulls on crust and thins the rock in the middle

compression

stress force that squeezes the rock until it folds or breaks

Shearing

stress that pushes mass of rock in two opposite directions

faults occur…

when enough stress builds up in trock, the rock breaks

Normal Faults

tension pulls rock apart in Earth’s crust, hanging wall slips down

hanging wall

block of rock that sits over the fault

footwall

block of rock that sits under fault

reverse faults

compression pushes rock together and hanging wall moves up and footwall goes down

strike-slip faults

shearing, rock on either side of fault slips past each other sideways

folds in crust

breaks in rock that form when compression shortens and thickens crust

anticlines

rock bends upward into arch

synclines

rock bends downward into V shape

anticlines and synclines

results of compression/ divergent boundaries

folded mountains

results when there is collision of two plates and compression of crust/ convergent boundaries

fault block mountains

form when two plates move away from each other in tension

formation of fault block mountains

hanging wall of normal fault slips down and the block in between now stacks above the surrounding valleys

plateaus

large area of land raised high above sea level, convergent boundaries

divergent boundary

normal fault line

convergent boundary

reverse fault line

transform boundary

strike-slip fault line

constructive plate boundaries

occur when 2 plates move away from each other

destructive plate boundaries

occurs when oceanic plate is forced under (or subducts) a continental plate

seismogram

record of earthquake’s seismic waves produced by seismograph

Ring of Fire

vast geological area of activity

how a seismograph works

seismic waves cause a simple seismograph drum to vibrate, which in turn cause the pen to record the drum’s vibrations

how seismogram shows earthquake waves

it records vibrations from an earthquake

how seismographs record earthquakes

seismic waves cause seismograph’s drum to vibrate, which causes the pen to record the vibrations

earthquake data seismograph reveals

earthquakes often occur along plate boundaries

earthquake risk

depends on how close a location is to a plate boundary

subduction of fault

one plate is forced under another

with plate tectonics

earthquakes are closely linked