Lecture Exam #2 Flashcards
Natural hazard vs. natural disaster (Chp. 5)
Hazard is the actual event (such as earthquake or flood), disaster is the negative impact following the hazard on a community (in the event of significant harm)
Why are natural disasters increasing in time and occurrence? (Chp. 5)
Increased population and density of it, climate change, and human influence (deforestation, removal of coastal vegetation)
What factors change a natural hazard to a disaster? (Chp. 5)
people’s lives and livelihoods are destroyed (disaster’s have a major effect on the economy of a community)
Why is New Orleans a vulnerable location for Natural disasters? (Hurt. Katrina); Chp. 5
- below sea level
- located on the flood plan of the Mississippi River
- on the coast of the gulf of Mexico
*essentially it was already surrounded by water, and sea levels are rising
What’s a man-made levee? What’s their implication?; Chp. 5
man-made levee: a structure made by man meant to divert/control the flow of water to temporarily prevent flooding
- sediment (dregs) blocked from wetlands
- wetland vegetation provided a natural barrier to natural disasters (removed to maker levee)
Describe the relationship between subsidence (sinking land) and sea level; Chp. 5
subsidence leads to higher sea levels and increased risk of flooding
Factors of Risk Impact; Chp. 5
characteristics at the psychological, family community, or cultural level that are associated with a higher chance of negative outcomes
*characteristics of a community that could lead to a more negative impact
Factors of Risk Assessment/Determination & Acceptable Risk; Chp. 5
- determination: type, location, consequences
- estimate: product of probability and consequences
- threshold: acceptable risks (society’s perception & willingness)
Describe the relationship of Hazard Frequency and Magnitude; Chp. 5
generally an inverse relationship
- magnitude: intensity of events (amount of energy released)
- frequency: recurrence interval of a disatrous event
How do scientists evaluate the potential for natural hazards?; Chp. 5
- Risk analysis/assessment
- study historic data (occurrence and recurrence of events, effects of past hazards)
Define: disaster forecast, prediction, and warning; Chp. 5
- forecast: the percent chance of an event happening
- prediction: SOMETIMES able to identify event characteristics (when, where, the size)
- warning: event has been predicted/forecasted for something that IS HAPPENING
What are lahars? Mudflows?; Chp. 5
Volcanic event where a mix of water and volcanic material (ash, magma) make a muddy mixture
- water tends to come from excess rain or melted snow
Why were the mudflows/Lahar at Nevada del Ruiz a NATURAL DISASTER?; Chp. 5
the impact was very severe and deadly (killed hundreds); as well as the economy suffered greatly
What is an earthquake?; Chp. 6
any sudden shaking of the ground caused by the passage of seismic waves through Earth’s rocks
Where is the epicenter of an earthquake?; Chp. 6
wherever the earthquake starts on the surface
Where is the focus and surface rupture/fault scrap located in an earthquake?; Chp. 6
- focus: where the earthquake starts
- surface rupture: the visible part of the epicenter
Define fault displacement; Chp. 6
measurement of the length or area of movement along a fault because of an earthquake
- slip rate: (mm/yr)
What are the fundamental cause of Earthquakes?; Chp. 6
rapid release of energy when rocks under stress fail along a fault
1) volcanic eruptions
2) landslides
3) magma movement in a volcano
What are the 3 types of stress’s rocks experience due to plate tectonics? What is the resulting deformation?
Chp. 6
1) compression
- rock to squeezes or pushes against another
2) tension
- rock pulls apart or gets longer
3) shear
- tectonic plates moving against one another, rock twists or changes shape
What is elastic rebound theory?; Chp. 6
how energy is released during an earthquake
- the ability of a rock to stand a magnitude level of stress before rupture
Define the differences between s-waves, p-waves, and surface waves; Chp. 6
s-waves: can only move through SOLID material
p-waves: can move through ANY material
surface: travel along earth’s surface
Which seismic waves cause the most damage?; Chp. 6
s-waves, because they move horizontally (building have a harder time withstanding that motion than vertical)
Why are surface wave amplified?; Chp. 6
when the waves moves from deeper, hard rock to shallower, softer rock they slow down and get bigger
- the energy piles up
How is the location of an Earthquake determined?; Chp. 6
by looking at seismograms from different recording stations
What is the logarithmic scale? How is it used?; Chp. 6
The scale used to quantify the magnitude of earthquakes.
- method for graphing and analyzing values in a compact form
At what depth do earthquakes typically occur and why?; Chp. 6
about 800 km deep into the surface;
- shallow depth = brittle failure - deeper depth = greater loss of energy before reaching the surface
What’s the difference between interpolate and intraplate earthquakes?; Chp. 6
interpolate: earthquakes on plate boundaries (more common)
intraplate: earthquakes in the interiors of plates
What are some effects of earthquakes?; Chp. 6
Shaking and ground rupture, liquefaction (once solid rock formation can be moved to flow like liquid)
How is the risk of an earthquake estimated? Long-term vs. short-term; Chp. 6
long-term: based on the knowledge of earthquakes in the past
short-term: watching prone faults for activity that may signify a coming earthquake (precursor events)
Why is Turkey so vulnerable to repeated large magnitude earthquakes?; Chp. 6
Because of the plate it lays on, and the surrounding boundaries. Every boundary around the Turkish plate is putting an immense amount of pressure onto the plate, creating a much higher chance of strong earthquakes.
What is a Tsunami and how can they be generated?; Chp. 7
wave produced by the sudden displacement of ocean water
can be triggered by:
- submarine earthquake
- landslide
- submarine volcano
How does a tsunami wave evolve? (From ocean rupture to reaching coastlines); Chp. 7
1) tigger occurs, pushing water upwards (creating a dome)
2) dome collapses, creating the wave
3) waves starts to move (deeper water will create a smaller wave moving faster, vs. shallow water with the opposite)
4) as the wave nears land, the velocity of it will decrease with the depth (but the height will increase)
5) wave hits land (or dies off in the ocean, if it’s a distant one)
What’s the difference between a Distant and Local Tsunami?; Chp. 7
distant: moves across the deep ocean at high speed for a while until it hits remote shorelines with little energy left
local: heads towards the nearest shoreline and hits it with a lot of energy left
What locations on Earth are more at risk for Tsunami’s?; Chp. 7
areas that are:
- closer distances to plate boundaries
- between or behind subduction zones
- low sea level
- little coastal protection
Describe the 2004 Boxing Day Indonesian Tsunami; Chp. 7
- why was the wave so big?; MAJOR earthquake hit right outside the country
- animal warning (elephants); ran to higher ground
- vegetation role in protecting coastlines; mangrove forests (trees with deep roots)
Where are volcanos on Earth?; Chp. 8
about 2/3 of ACTIVE vols. are around the Pacific “RING OF FIRE”
- plate boundaries
What type of magma compositions are produced at plate boundaries? (convergence, divergent, hotspots); Chp. 8
convergence: most common vols. (Ring of Fire)
divergent: pillow basalts (lava flows that turns solid once it hits water
hot spots: mantle plums (magma rising from the crust mantle boundary)
How is magma generated from the mantle?; Chp. 8
mantle melting; temperature and decompression
- decompression melting
- addition of volatiles
What is the Bowen Reaction Seres?; Chp. 8
temperature at which minerals crystallize when cooled, or melt when heated
- related to Earth being a silicate system
What is crystal fractionation?; Chp. 8
the process of separating two or more crystalline solids based on the difference in their melt chemistry
How does the change in melt chemistry and viscosity due to crystallization relate to a magmas explosivity?; Chp. 8
the crystallization of super small crystals increases the magmas viscosity (and therefore its explosively)
What are the different types of volcanos (5)? Type of magma they produce, type of eruption (effusive vs. explosive); Chp. 8
shield volcano: built from basaltic lava flows, slope if very gentle near top
- effusive (low levels of gas & silica in magma)
composite volcano: cone shaped
- explosive (higher silica content, & more explosive activity)
cinder volcano: small and formed by tephra (ash)
- explosive (due to pressure built in magma chamber)
volcanic domes: viscous magma
- relatively gentle EFFUSIVE eruptions (magma rises slowly, gas has time to escape)
calderas: large eruption collapsing vols. into a crater
- explosive (high pressure, high silica content)
Characteristics of Exposive Eruptions; Chp. 8
magma fragmentation, felsic magma, explosion sends a lot of material (ash, magma, etc.) into the sky
What is a pyroclastic flow?; Chp. 8
THINK Pompeii
dense, destructive mass of hot ash, lava fragments, and gases moving quickly downslope
What are the parts of an explosive pinion eruption column?; Chp. 8
TOP (last)
- ash plume
- magma conduct
- volcanic ash fall
- layers of ash and lava
- stratum
- magma chamber
BOTTEM (first)
Why was Mount St Helens such a natural disaster?; Chp. 8
- landslide beforehand (decreasing pressure)
- the eruption was 9-hours long and had a LATERAL BLAST
Describe 3 volcanic hazards; Chp. 8
- ejection of bombs
- lahars/mudflows; water mixing with mud and other pyroclastic material
- volcanic gas; poisonous gas in the air
- volcanic winter (Mt. pinatubo); blocking solar radiation, REALLY bad for air traffic
Where is most magma produced in the submarine setting?; Chp. 8
basaltic, effusive lava flows
Where (plate boundaries) do most explosive submarine eruptions occur?; Chp. 8
on or near subduction zones
What is a pumice raft? What eruption produces them?; Chp. 8
floating raft of pumice
- submarine explosive eruption
Physical vs. Chemical Weathering; Chp. 10
physical: breakdown of rock from the effects of heat, water, ice
chemical: breakdown of rock due to chem reaction of water, gases, etc.
POSITIVE FEEDBACK
REINFORCE ONE ANOTHER
What is the relationship between climate and chemical weathering?; Chp. 10
high temperatures and greater rainfall increase the rate of chemical weathering
- positive relationship
What are types of chemical weathering?; Chp. 10
- oxidation (metals rusting)
- hydrolysis (adding water to mineral and altering crystal structure to make new mineral)
What is a mass movement?; Chp. 10
earth’s surface is mostly unstable, leadings to MASS WASTING (downslope motion of materials, aka a landslide)
Why are slopes unstable and where do mass movements occur?; Chp. 10
most of Earth’s crust is made of sediment material/rocks
- occur along hillsides/mountains (slopes)
What are the types of landslides (5)?; Chp. 10
- slope creep; gradual movement downslope
- rotational slides/slumps; curved surfaces, tends to form steps
- transitional slopes; planer surfaces, fractures or joints
- free face; stronger rock (i.e. Granite), vertical cliff face
- avalanche anatomy; caused by wind, temperature, snow and terrain
Difference between permanent vs. ephemeral streams/rivers; Chp. 9
permanent: always flow
ephemeral: flow for short periods of time (like after a rainfall)
What are the parts of a river?; Chp. 9
cut bank, point bar, flood plain, delta, oxbow lake, alluvial fan, natural levees
What factors influence flooding?; Chp. 9
- heavy rainfall
- dam failures
- rapid snowmelt/ice jams
How can we prevent floods?; Chp. 9
- levees and floodwalls
- retention ponds
- channelization (the consequences)
- channel restoration
Difference between asteroids, meteoroids, and comets; Chp. 12
asteroids: small rocky object orbiting the Sun
meteoroids: a small piece of asteroid or comet
comets: ball or ice and dust orbiting the Sun
What is the physical process associated with aerial burst and impact craters? ; Chp. 12
aerial burst: object explodes in the sky after entering Earth’s atmosphere
impact craters: object hit the Earth
List 3 possible causes of mass extinctions ; Chp. 12
1) asteroid impact
2) widespread volcanic activity
3) rapid and dramatic changes in climate
What is the main evidence for the impact hypothesis of the late Cretaceous mass extinction? ; Chp. 12
a meteorite big enough to be called a small asteroid hit Earth (rocks around the impact area contained large amounts of iridium)
What is the main evidence for the impact hypothesis of the Late Pleistocene (younger dryas) megafauna? ; Chp. 12
“black mats”, or areas of very rich soil found across sections of North America
What are the physical, chemical, and biological consequences of impacts from a large asteroid or comet? ; Chp. 12
Chp. 12
How does magma rise through the mantle and crust to be at the surface?; Chp. 8
gas; decompression melting causing rifting (making the magma below rise and fill spaces with lower pressure)
Earthquake depths at different plate boundaries
Divergent: about 30 km
Convergent: about 700 km
Transform: about 20 km
Bowen Reaction Series Minerals (highest temp to lowest)
olivine, pyroxene, amphibole, biotite
crystallization begins at 1400 C (olivine) and goes to 650 C (P Feldspar, Muscovite, Quartz)
What are the types of faults produced from stress?
- compressive stress produces reverse faults (convergent boundary)
- tensional stress produces normal fault (divergent boundary)
- shear stress produces transform faults (strike slip boundary)
Faults expected at different plate boundaries
Normal fault -> divergent
Reverse -> convergent
Strike slip -> transform
Bowen Reaction Series Minerals (calcium)
plagioclase feldspar to SODIUN RICH feldspar
Bowen Reaction Series, details
- after melt left with a low iron material
- IRON AND MAGNESIUM LEVELS GET LOWER AND LOWER until the material is left with silicate and oxygen
- removal of heavier materials, left with lighter
- low viscosity to more explosive items
