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)
