Exam 2

Question 1

epicenter

Answer 1

the spot on the ground right above where the earthquake starts

Question 2

hypocenter

Answer 2

the actual place underground where the earthquake begins

Question 3

epicenter vs hypocenter

Answer 3

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

Question 4

magnitude

Answer 4

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

Question 5

intensity

Answer 5

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

Question 6

magnitude vs intensity

Answer 6

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

Question 7

P-waves (primary waves)

Answer 7

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

Question 8

S-waves (secondary waves)

Answer 8

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

Question 9

surface waves

Answer 9

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

Question 10

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

Answer 10

surface waves

Question 11

seismograms

Answer 11

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”

Question 12

how do seismograms work?

Answer 12

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

Question 13

what do seismograms measure?

Answer 13

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

Question 14

amplitude

Answer 14

height of the wave

Question 15

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

Answer 15

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

Question 16

divergent boundaries

Answer 16

places where 2 tectonic plates are moving away from each other

Question 17

geologic formations from divergent boundaries

Answer 17

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

Question 18

convergent boundaries

Answer 18

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

Question 19

geologic formations from convergent boundaries

Answer 19

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

Question 20

transform boundaries

Answer 20

where 2 tectonic plates are sliding past each other horizontally

Question 21

geologic formations from transform boundaries

Answer 21

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

Question 22

normal faults

Answer 22

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

Question 23

reverse/thrust faults

Answer 23

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

Question 24

strike-slip fault

Answer 24

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

Question 25

what drives plate tectonics?

Answer 25

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

Question 26

stratovolcanoes

Answer 26

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

Question 27

shield volcanoes

Answer 27

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

Question 28

scoria cones

Answer 28

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

Question 29

flood basalts

Answer 29

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

Question 30

calderas

Answer 30

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

Question 31

volcanic domes

Answer 31

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

Question 32

lahars

Answer 32

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

Question 33

lahars: hazard to humans

Answer 33

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

Question 34

pyroclastic flows

Answer 34

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

Question 35

pyroclastic flows: hazard to humans

Answer 35

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

Question 36

ash fall

Answer 36

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

Question 37

ash fall: hazard to humans

Answer 37

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

Question 38

volcanic gas

Answer 38

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

Question 39

volcanic gas: hazard to humans

Answer 39

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

Question 40

lava

Answer 40

molten rock that flows from a volcano during an eruption

Question 41

lava: hazard to humans

Answer 41

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

Question 42

tephra

Answer 42

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

Question 43

tephra: hazard to humans

Answer 43

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)

Question 44

high silica

Answer 44

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

Question 45

low silica

Answer 45

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

Question 46

high temp in magma

Answer 46

more fluid, gentle eruptions (low viscosity, basaltic)

Question 47

low temp in magma

Answer 47

thicker, more explosive (high viscosity, rhyolitic)

Question 48

volatiles

Answer 48

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

Question 49

where do we find volatiles?

Answer 49

mainly in subduction zones and within magma

Question 50

how do volatiles get there?

Answer 50

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

Question 51

tsunami

Answer 51

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

Question 52

what causes tsunamis?

Answer 52

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

Question 53

how do tsunami waves evolve as they travel?

Answer 53

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

Question 54

what can humans do to stay safe from tsunamis?

Answer 54

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