NATURAL DISASTERS Flashcards
what is an earthquake
a sudden, violent shaking of the ground
what causes earthquakes
the release of tension that builds up in the crust sometimes
where do earthquakes happen?
on all 3 plate boundaries and faults
faults
small cracks
focus
the actual point on a focus where the earthquake occurs
epicenter
the point on the earths surface directly above the focus
Elastic rebound hypothesis
during the earthquake/right before the rocks become deformed and after an earthquake the rocks go back to normal
pyroclastic material
quick moving, swirling ball of hot rock debris, gas ect. that is a part of volcanic eruptions
what is a tsunami
a series of big powerful waves caused by an earthquake or volcanoes on the ocean floor
how is it dif than a normal wave
normal waves are caused by wind and are on the surface but tsunamis displace more water, go from floor to surface (normal just surface) caused by eq or volcano
What is a warning sign of a tsunami?
dramatic fall and rise in water levels/tidereceeding water
What are some effects of tsunamis?
cites destroyed and drowned in waterkills hundreds of thousandswipes out buildings and houses
body waves
less destructive than surface, but teach us bat earths insides2 types- p and s waves
surface waves
larger and more destructive than body waves, travel along the surface of earth and move slowly
surface and body compare and contrast
contrast b-travel inside s-travel on surf.less destructive morecompareboth are outcomes of earthquakes
s waves
secondary waveslower waveshake wave, vibrates, moves side to sidecan only move through solids
p waves
first wavefasterpush pull wavestraight can pass through solid and liq.
How can you determine the relative distance of an earthquake, just by looking at a seismograph reading?
the distance btwn the s and p wave
foreshocks
small earthquakes that sometimes come before a major earthquake
aftershock
an earthquake that occurs sometime soon after an earthquake– can cause damage
why do most earthquakes cause little damage and little loss of life
bc even great earth quakes release all of its elastic energy
2 types of seismic waves
body and surface
what are seismic waves
the energy produced from an earthquake that cause a vibration
how are the earthquakes fault, epicenter and focus all related
the earthquake occurs on the fault. the eq’s focus occurs on the fault and the epicenter is directly above the focus which is on the fault.
2 ways to measure earthquakes
richterscale and moment magnitude
what is the richter scale
measures intensity determined by reading changes in seismographic lines
what is the moment magnitude
measures intensity of shaking determined by studying deformed rocks and displacement of land along faultmore commonly used
why are tsunamis dangerous
the force is v powerful and destructive
what should people do after they receive a tsunami warning
leave and movelisten to radio and tv and try to get to a high point of a sturdy building
beam girder
————| | | | |
steel arch
^ ^ ^——-| | |
suspension
/| | | \ / | | | | | | | | \ /| | | | | | | | | | | | -—————————| | | |
cantilever-truss
/-—/|xxxx|——–| | |
cable stay
/ \ / /|\ \ / / | \ \ / / | \ -————- |
bearings
absorb shock/ side-to-side vibrations and the deck from receiving brunt shaking made of rubber or plastic btwn two rods
shear links
to absorb most of the shaking lower downthey are made of cross beams that connect the towers
what location is the least common for earthquakes to occur?
divergent boundary
what location is the most common for earthquakes to occur?
fault
If you were to be stranded during an earthquake, would you prefer the earthquake to measure a magnitude 2 or magnitude 8 on the Richter Scale. Explain.
A 2, because the Richter scale is set on a scale of 1-10 and is based on the intensity of shaking during an Earthquake.1= not a lot of shaking10= most shaking
tsunamis occur where?
in the ocean
what causes tsunamis
sudden movement of the ocean due to earthquakes, landslides on the sea floor, land slumping into the ocean, large volcanic eruptions
