Geology Final Exam

Front 1

Earthquake

Back 1

occurs when rocks under stress suddenly fail along geologic fault

Front 2

Elastic Rebound Theory

Back 2

rocks deform elastically, then rebound during an earthquake rupture

Front 3

Focus

Back 3

point where main slip occured

Front 4

Epicenter

Back 4

point on surface above focus

Front 5

Primary waves

Back 5

Fastest waves 6 km/sec, moves through solid and liquid, compressional

Front 6

Secondary waves

Back 6

slower 3km/sec, moves through solid only, shearing

Front 7

fault slip

Back 7

distance of the displacement

Front 8

recurrence interval

Back 8

time between ruptures

Front 9

aftershocks

Back 9

a smaller earthquake triggered by a large earthquake

Front 10

foreshock

Back 10

small earthquake that occurs shortly before a mainshock near its focus

Front 11

seismograph

Back 11

instrument that records seismic waves generated by eathquakes

Front 12

surface waves

Back 12

travel around Earths surface

Front 13

Magnitude scale

Back 13

scale used for estimating the size of an earthquake using the logarithm of the largest ground motion registered by a seismograph

Front 14

Fault mechanism

Back 14

tells us whether the rupture was a strike-slip, normal, or reverse fault.

Front 15

tsunami

Back 15

occurred by a large earthquake beneath the ocean causing a destructive wave

Front 16

seismic hazard

Back 16

describes frequency and intensity of seismic shaking and ground disruption that can be expected over the long term at some specific location

Front 17

seismic risk

Back 17

describes the damage that can be expected over a long period of time in a specific region

Front 18

compressional waves

Back 18

travel with a push and pull motion

Front 19

shear waves

Back 19

travel with a side to side motion

Front 20

Basaltic lavas

Back 20

erupt when hot, fluid magmas fill up a volcanos plumping system and overflow, dark

Front 21

andesitic lavas

Back 21

temps are lower than basaltic, high silica content, flow more slowly and lump up in sticky masses, intermediate

Front 22

rhyolitic lavas

Back 22

rich in silica, viscous, piles up in thick bulbous deposits, light

Front 23

Mafic

Back 23

little/no silica

Front 24

Felsic

Back 24

silica/viscous

Front 25

Types of basaltic lava

Back 25

Pahoehoe (ropey), followed by Aa, and pillow (underwater volcanism)

Front 26

tuffs

Back 26

volcanic rocks formed by small fragments of pyroclasts segments

Front 27

breccias

Back 27

volcanic rocks formed by larger segments

Front 28

pyroclastic flows

Back 28

deadly, volcano ejects hot ash and gases in a cloud that rolls downhill at highspeeds

Front 29

Shield volcano

Back 29

erupts from central vent as well as cracks on side b/c lava is so fluid, each layer represents many hundreds of thin flows of basaltic lave, gentle slope ex) Mauna Loa (HI)

Front 30

Volcanic Dome

Back 30

viscous felsic lava piles up over the vent, erupts through central vent, ex) mt st helens

Front 31

Cinder-cone volcano

Back 31

pyroclastic materials and lava form layers that dip away from center at summit, vent may become filled with volcanic debris, steeper than dome

Front 32

Stratovolcano

Back 32

similar to cone, more pyroclasts, lava solidifies in fissures radiating dikes, central vent filled with lava from last eruption, ex) mt fiji, japan

Front 33

Caldera

Back 33

collapsed craters, violent eruption empties magma chamber, cant support overlying rock, collapses leaving steep walled basin. leaves a caldera lake in crater ex) crater lake (oregon)

Front 34

Phreatic or steam explosion

Back 34

mixed with steam, engulf area and suck up oxygen, death common

Front 35

Diatreme

Back 35

surrounding rock becomes eroded, radiating dikes surrond face, known as ship rock, precious gems and materials found here

Front 36

Hot Spots

Back 36

very deep source, plume of hot magma rising for miles, when magma erupts, plates move

Front 37

lava table

Back 37

basaltic lave solidifies and leaves this structure

Front 38

continental drift

Back 38

large scale movements of continents

Front 39

Divergent

Back 39

<--------|-----------> NEw rocks created

Front 40

Convergent

Back 40

-------><------------ Rocks destroyed

Front 41

Transform Fault

Back 41

------------> neither created or destroyed
<------------

Front 42

subduction

Back 42

one plate descending beneath the other

Front 43

Subduction styles

Back 43

1) shallow angle (Chilean subduction, volcanism, seismic activity)
2) high angle (very little melting, volcanism, and seismic activity)

Front 44

Determining Plate Velocities

Back 44

1) magnetic pole reversal
2) age of seafloor
3) satellites
4) hot spots

Front 45

characteristics of divergent plate boundaries

Back 45

-ophiolite sequence
-peridotite
-pillow lava
-Gabbro
-sediments
-dikes

Front 46

shields

Back 46

large tectonic providence within a continent that is tectonically stable and where ancient crystalline basement rocks are exposed at the surface

Front 47

rejuvenation

Back 47

mountains rise again and brought back to a more youthful stage

Front 48

Epelorogeny

Back 48

no plate collision ex) black hills
up- dome
down-basin

Front 49

Orogenic

Back 49

Plate collision (vertical movement) ex) Himalayas, Appalachians