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Exam 2 Study Guide
Terms in this set (70)
When was Hurricane Katrina?
made landfall in August 29, 2005 to the east of NOLA
What was the cause of severity from hurricane Katrina?
-sea level rise
-poor coordination for emergency response
What criteria does a natural disaster have to have to be considered a natural disaster?
-particular event in which 10 or more are killed
-100 or more are affected
-a declaration of state emergency is issued or a request for international assistance
What is a natural disaster?
dangerous natural processes including earthquakes, floods, volcanic activities, landslides, and storms
Why do natural processes become hazards?
When people live or work in the areas where they occur
What is magnitude?
The intensity of a natural hazard in terms of the amount of energy released
What is frequency?
The recurrence interval of a disastrous event. q
What is the relationship between frequency and magnitude?
-generally an inverse relation between them
-they're controlled by natural factors
Are all natural hazards deadly or harmful?
No, some have benefits such as creating new land, supplying nutrients to soil, flushing away pollutants, and changing local landscape.
What are death and damages?
Great loss of human life, grave damages to property, and changes in properties of earth materials
Developed v. Developing countries damages
- more life loss from a major natural disaster in a developing country
-more property damage in a more developed country
What is a catastrophe?
Disastrous situations requiring a long process to recovery from grave damages
What is a forecast?
The certainty of the event is given as the percent chance of happening
What is a prediction?
Sometimes possible to accurately predict when, where, type, and size of the certain natural hazardous events
What is a warning?
A hazardous event has been predicted or a forecast has been made, the public bus be warned
What two components make up risk assessment?
What is risk determination?
type, location, probability, and consequences
What is risk threshold?
-probability and consequences into perspective
What is a reactive human response to hazard?
Primarily after the hazardous event
-recovery phases are search response, rescue, restoration, and reconstruction
What is an anticipatory response to hazards?
Perceiving, avoiding, and adjusting to hazard for avoiding or minimizing the impacts disasters
What is an earthquake?
-violent ground shaking phenomenon by. the sudden release of strain energy stored in rocks
What instrument used to measure an earthquake?
What are human activities that could induce earthquakes?
-reservoir induced earthquakes
-deep waste disposal
What is focus?
The point at depth where the rocks rupture to produce the earthquake
What is epicenter?
The location on the surface of earth above the focus
What is moment magnitude?
Measure of the energy released by the earthquake
What is Richter magnitude?
Named after famous seismologist Charles Richter, it describes the energy released by an earthquake. It is based upon the amplitude or size of the largest seismic wave produced by an earthquake.
What is the Earthquake Magnitude Scale?
the Richter scale
-related to amplitude of ground motion
-increasing one order in magnitude
-a tenfold increase in amplitude
What is the modified Mercalli scale?
-qualitative severity measurement of damages and ground movement
-based on ground observations instead of instrument measurement
-scale depends on the earthquakes magnitude
What is an inter plate earthquake?
Earthquakes that are concentrated along plate boundaries and nearly all catastrophic earthquakes are shallow earthquakes (ex. divergent, transform, convergent)
What is an intra plate earthquake?
Earthquakes occur within the plate away from plate boundaries (ex. New Madrid earthquake and Charleston earthquake)
What are the different fault types?
Normal, reverse, thrust, and strike slip
What are seismic wave types?
- P waves
What are the properties of seismic waves?
-earths focus and epicenter
-seismic wave propagation is outward from the focus
-the waves travel differently through different rock materials
What are P waves?
Compressional waves, travel fastest through all physical states of media
What are S waves?
Shear waves, travel slower than P waves, but faster than surface waves. Only propagate through solid materials
What are surface waves?
Waves that move along earths surface, travel the slowest, but cause the most damage
What are seismographs?
A device to record the seismic waves
What are seismograms?
the record of an earthquake
What is material amplification?
the intensity (amplitude of vertical movement) of ground shaking more severe in unconsolidated materials
What is supershear?
-It occurs when the propagation of rupture is faster than the velocity of sheer waves or surface waves produced by the rupture
-Produce shockwaves that produce strong ground motion along the fault
What is directivity?
another amplification affect, the intensity of seismic shaking increases in the direction of the fault rupture
What is a tsunami?
Produced by the sudden vertical displacement of ocean water
What triggers a tsunami?
any rapid uplift or subsidence of the sea floor such as, submarine earthquake, landslide, volcanism, impacted asteroid or comment
What are mega thrust events?
A mega tsunami from asteroid impact, a wave about 100 times higher than the largest tsunami produced by an earthquake
What are the 4 stages of a tsunami?
1. Earthquake rupture inn seafloor pushes water upwards starting tsunami
2. Tsunami moves rapidly in deep ocean
3. As the tsunami nears land it slows down, but is squeezed upwards, increasing the heigth
4. Tsunami heads inland, destroys all in its path
What is a local tsunami?
Heads in the opposite direction toward the nearby land and arrives quickly following an earthquake
What is a distant tsunami?
Travels out across the deep ocean at high speed for 1000 of kilometers to strike remote shorelines with very little loss of energy
What regions are at risks for tsunamis?
All oceans and some lake shorelines and some coasts. (high risk regions are the cascadia subduction zone)
What are ways to minimize tsunami hazards?
-detection and warning
-construction of tsunami runup maps
-land use planning
What is probability analysis?
The risk of a particular event may be defined as the product of the probability of that event occurring and the consequences
What is risk?
situation involving exposure to danger
What are adjustments to tsunami hazards?
-leave the beach and low line coastal area
-stay out of dangerous areas until further notice
-listen to the warming sirens
-move to higher ground
What is volcanism?
Volcanic activity, directly related to plate tectonics and most active volcanoes are located near plate boundaries
What is the pacific ring or fire?
Where approximately 2/3 of active volcanoes are located
How is magma formed?
The temperature increases with depth close to the temperature at which rocks melt
What is the source magma?
What is viscosity?
The liquid resistance to flow
What are the types of volcanoes?
What are shield volcanoes?
Build up almost entirely from numerous basaltic lava flows, the slope of a shield volcano is very gentle near the top but increases on the flanks
What are composite volcanoes?
Known for their beautiful cone shaped, characterized by magma with an intermediate silica content, distinguished by a mixture of explosive activity and lava flows
What are volcanic domes?
Characterized by viscous magma with a relatively high silica content, common rock type produced by this magma is rhyolite
What are cinder cones?
Relatively small volcanoes formed from tephra, mostly volcanic ash in larger particles, volcanic bombs
What are volcanic features?
-craters and vent
-caldera (collapsed craters, typically from explosive eruptions)
-hot springs and geysers
-fissure line (basaltic lava flow)
What happened at Mt. St. Helens?
-May 18, 1980
-Erupted after 120 year dormancy
-Earthquake at 4-5 magnitude
-triggered massive landslide
-18 km distance down Toutle River
-lateral blast impacted 19 miles 1000 km/h
-mudflows reached nearly 100 km (60 miles)
-killed 54 people
-damaged 100 homes
-800 million feet of timber: total cost 3 billion
What happened at Mount Pinatubo?
-June 15-16, 1991
-Destroyed U.S military base
-1 ft of ash covered buildings over a 40 km radius
-huge cloud of ash 40 km wide into nearly 40 km elevation
-affected global climate (cooler summer the following year)
How do you forecast volcanic activity?
-Seismic activities: earthquakes as precursors
-Thermal, magnetic and hydrologic conditions
-amount of volcanic gas emission, both rate and composition
-topographic monitoring:tiling and special bulging
-remote sensing:radar 3-D interferometry
-geologic history of a volcano
from the vent of a crater or along a line of fissure
-enormous amount of rock fragments, volcanic glass fragments and volcanic bombs
-associated with explosive volcanic eruptions
-ash fall from a more vertical ash eruption
debris flow and mudflows
-the most secondary volcanic hazard
-collectively known as a lahar, an Indonesian term
-from collapse of volcano slopes
-sudden melting of snow caps and glaciers at the top of a volcano
-rapid downslope flow at the speed of 50 km/h
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