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GEOL 1170 > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

epicenter

A

the spot on the ground right above where the earthquake starts

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2
Q

hypocenter

A

the actual place underground where the earthquake begins

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3
Q

epicenter vs hypocenter

A

the epicenter is the point at the surface that lies directly above hypocenter

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4
Q

magnitude

A

the amount of energy the earthquake releases, measured on a scale (like the Ritcher scale)

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5
Q

intensity

A

how strong the earthquake feels in a specific area, including the damage it causes

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6
Q

magnitude vs intensity

A

magnitude is the total energy of the earthquake and doesn’t change based on where you are, while intensity describes what you feel in different places

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7
Q

P-waves (primary waves)

A

fastest seismic waves
travels in the earth
moves like a slinky (compress then release)
can travel through solids, liquids, and gases

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8
Q

S-waves (secondary waves)

A

slower seismic waves
travels in the earth
moves like a wave (up and side, side to side)
can travel through solids only

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9
Q

surface waves

A

waves that travel along the earth’s surface, causing the ground to roll or sway
Rayleigh waves and Love waves

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10
Q

what waves are responsible for most of the damage during an earthquake?

A

surface waves

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11
Q

seismograms

A

the record or graph that shows the seismic waves detected by a seismograph (the instrument that measures earthquakes)
it’s like an earthquake’s “fingerprint”

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12
Q

how do seismograms work?

A

a seismograph has a heavy weight attached to a pen, and when the ground shakes, the pens moves and draws a line on a rotating drum or digital system
p-waves show up first, followed by s-waves, then surface waves

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13
Q

what do seismograms measure?

A

amplitude = how strong the earthquake is
time between wave arrivals = how far away the earthquake’s epicenter is
p-waves arrive first, then s-waves, and the gap between them helps determine distance

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14
Q

amplitude

A

height of the wave

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15
Q

what information do you need to get the measurements you want using a seismogram?

A

at least 3 seismograms from different locations to pinpoint the earthquake’s epicenter (this is called triangulation)

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16
Q

divergent boundaries

A

places where 2 tectonic plates are moving away from each other

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17
Q

geologic formations from divergent boundaries

A
  1. mid-ocean ridges: form when plates separate and magma rises to create new ocean floor
  2. rift valleys: can form where plates diverge
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18
Q

convergent boundaries

A

where 2 tectonic plates are moving toward each other, often leading to one plate being forced beneath the other (subduction)

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19
Q

geologic formations from convergent boundaries

A
  1. mountain ranges: form when 2 continental plates collide
  2. volcanic arcs: form when an oceanic plate sinks beneath a continental plate
  3. ocean trenches: form when one oceanic plate subducts beneath another
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20
Q

transform boundaries

A

where 2 tectonic plates are sliding past each other horizontally

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21
Q

geologic formations from transform boundaries

A
  1. fault lines
  2. earthquakes are frequent
    (no major landforms like mountains or trenches are typically created
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22
Q

normal faults

A

aka dip-slip fault
a fracture in the Earth’s crust where the rock above the fault moves down relative to the rock below
vertical movement
crust is being pulled apart

23
Q

reverse/thrust faults

A

where the upper block of rock moves up and over the lower block
crust is being compressed
vertical movement

24
Q

strike-slip fault

A

where the plates slide side by side past each other
horizontal movement
common at transform boundaries

25
Q

what drives plate tectonics?

A

convection currents in the Earth’s mantle
hot material from the deep mantle rises, cools, and sinks back down, creating a cycle that moves tectonic plates

26
Q

stratovolcanoes

A

large, steep-sided volcanoes built from alternating layers of lava flows and ash
steep slopes and tall, classic “volcano” shape
often produce explosive eruptions due

27
Q

shield volcanoes

A

broad, gently sloping volcanoes formed by low-viscosity lava that spreads out over large areas
wide and flat with gentle slopes
eruptions are usually non-explosive

28
Q

scoria cones

A

small, steep-sided cones made mostly of volcanic rock fragments (scoria or cinders)
typically short-lived and small in size
eruptions are moderately explosive but localized

29
Q

flood basalts

A

huge, flat areas covered by layers of basalt lava from fissure eruptions, not from a central volcanic cone
massive, wide areas of flat lava flows
eruptions involve low-viscosity lava spreading out in sheets over great distances

30
Q

calderas

A

large, basin-like depressions formed when a volcano collapses after a massive eruption
often form after explosive eruptions empty the magma chamber and the volcano collapses

31
Q

volcanic domes

A

small, dome-shaped mounds formed by slow, viscous lava piling up near the vent
steep-sided domes formed by very thick lava
eruptions are often slow and can lead to dome collapse and pyroclastic flows

32
Q

lahars

A

mudflows or debris flows made of volcanic ash, rock, and water that rush down the slopes of a volcano

33
Q

lahars: hazard to humans

A

extremely destructive, can burry entire towns and sweep away buildings, bridges, and roads
fast moving and hard to escape
can happen long after an eruption

34
Q

pyroclastic flows

A

fast-moving currents of hot gas, ash, and rock that race down the sides of a volcano during an explosive eruption

35
Q

pyroclastic flows: hazard to humans

A

deadly, they can travel at speeds over 100 mph and reach temperatures over 1,000F
can obliterate everything in their path, including homes, forests, and roads
virtually impossible to outrun and cause instant fatalities due to intense heat and toxic gases

36
Q

ash fall

A

ash particles ejected from a volcano that fall to the ground over wide areas

37
Q

ash fall: hazard to humans

A

dangerous for breathing, especially for people with respiratory conditions
can collapse roofs if it accumulates and disrupt transportation
contaminates water sources and damages crops

38
Q

volcanic gas

A

gases such as CO2, SO2 (sulfur dioxide), and H2S (hydrogen sulfide) released from a volcano

39
Q

volcanic gas: hazard to humans

A

toxic and suffocating, can cause respiratory issues or death if inhaled in large amounts
CO2 can settle in low areas and displace oxygen, suffocating people and animals
SO2 can lead to acid rain, damaging crops, buildings, and water supplies

40
Q

lava

A

molten rock that flows from a volcano during an eruption

41
Q

lava: hazard to humans

A

slow-moving, but can destroy anything in its path (buildings, forests)
causes fires and burns, but it’s usually easy to escape if you’re far enough away
property damage is more common than direct harm to humans due to its slow flow

42
Q

tephra

A

solid volcanic material, including ash, pumice, and larger rocks, ejected during an eruption

43
Q

tephra: hazard to humans

A

larger tephra can injure or kill people and damage buildings if it falls in populated areas
smaller particles can cause breathing problems and disrupt air travel (can damage airplane engines)

44
Q

high silica

A

thick, sticky, explosive eruptions (e.g. rhyolite)
found at convergent boundaries

45
Q

low silica

A

thin, fluid, gentle eruptions (e.g. basalt)
found at divergent boundaries and hot spots

46
Q

high temp in magma

A

more fluid, gentle eruptions (low viscosity, basaltic)

47
Q

low temp in magma

A

thicker, more explosive (high viscosity, rhyolitic)

48
Q

volatiles

A

dissolved gases in magma, like water vapor (H2O), carbon dioxide, and sulfur dioxide (SO2)

49
Q

where do we find volatiles?

A

mainly in subduction zones and within magma

50
Q

how do volatiles get there?

A

from subduction oceanic plates carrying water and sediments, dehydration of minerals, and melting mantle/crust

51
Q

tsunami

A

a series of extremely long waves caused by a sudden displacement of the ocean

52
Q

what causes tsunamis?

A

underwater earthquakes (most common), volcanic eruptions, landslides, and meteor impacts can cause tsunamis

53
Q

how do tsunami waves evolve as they travel?

A

in deep water, tsunamis move quickly (up to 500-600 mph) but have low wave heights (often unnoticed)
as they approach shallow coastal areas, they slow down and the wave height increasing, creating large, destructive waves that flood inland

54
Q

what can humans do to stay safe from tsunamis?

A

evacuate coastal areas if a tsunami warning is issued
move to higher ground or inland as quickly as possible

GEOL 1170 (1 decks)

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