Natural Hazards 3 Main Processes - ANSWER - internal forces within the
earth (plate tectonics)
- external forces on earth's surface (atmospheric effects)
- gravitational attraction (downslope movement/avalanche)
Hazard - ANSWER a process that poses a potential threat to people or the
environment
Risk - ANSWER the probability of an event occurring multiplied by the
impact on people or the environment
Disaster - ANSWER a brief event that causes great property damage or loss of
life
Catastrophe - ANSWER a massive disaster
More likely to be catastrophic - ANSWER tsunamis, earthquakes, volcanoes,
hurricanes and floods
less likely to be catastrophic - ANSWER landslides, avalanches, wildfires,
tornadoes (affect relatively smaller areas of population)
Magnitude- Frequency Concept - ANSWER - the impact of a hazard is a
function (relationship between two variables) of both its magnitude (i.e., energy
released) and frequency
- an inverse relationship
- as one goes up, the other goes down
Geologic Cycle - ANSWER throughout earths 4.6 billion year history the
materials on or near the surface have been created and modified by physical and
chemical processes
- tectonic cycle, rock cycle and hydrologic cycle
,Tectonic Cycle - ANSWER - involves the creation, movement and destruction
of tectonic plates
- new land is formed at mid-ocean ridges and land is destroyed at subduction
zones
- process is driven by earths internal energy
tectonic plates - ANSWER large blocks of the earth's crust that form its outer
shell
14 plates
Earth's Internal Structure - ANSWER - inner core is extremely hot and solid
- asthenosphere (upper mantle) is composed of hot magma with some flow
- lithosphere is a thin and brittle crust
Plate Tectonics - ANSWER - crust is broken into fragments
- movement of the plates is caused by convection currents within the mantle
- plate boundaries do not match with continents/oceans
types of crust - ANSWER - oceanic: dense, thin (averages 7km thickness)
Continental: relatively buoyant, thick (averages 30 km thickness)
whichever plate is more dense is the one that is going to sink
types of plate boundaries - ANSWER divergent, convergent & transform
Divergent Plate Boundaries - ANSWER - plates move away from each other
- new land is created
- results in seafloor spreading and causes oceanic ridges to form (e.g., Mid-
Atlantic Ridge)
Convergent Plate Boundaries - ANSWER - plates move towards each other
- collisions involving oceanic and continental crust result in subduction zones
(dense ocean plates sink and melt, melted magma rises to form volcanoes)
- collisions involving two continental plates result in collision boundaries
(neither plate sinks, tall mountains tend to form i.e., Himalayas)
Transform Boundaries - ANSWER - plates slide horizontally past each other
- zone along which the movement occurs is called a transform fault
- most located beneath oceans
, Hotspots - ANSWER - found away from plate boundaries, where magma rises
from mantle
- magma erupting at the surface results in the formation of volcanoes
- string of islands are indicative of a hotspot (i.e., Hawaii)
Rock Cycle - ANSWER a rock is an aggregate of one or more minerals
refers to a group of interrelated processes that produce the 3 different rock types
Hydrologic Cycle - ANSWER the movement and exchange of water among
the land, atmosphere and oceans by changes in state
- solar energy drives the movement of water among the atmosphere, oceans and
continents
Residence time - ANSWER the resident time of a water molecule ranges from
days in the atmosphere to thousands of years in the ocean
Hazards can be understood - ANSWER - scientists observe a event and form
possible explanations
- then a hypothesis is formed
- data is collected to test hypothesis
- knowing the cause allows for the identification of where hazards may occur
- knowledge of past events aids in predicting future events
prediction - ANSWER a specific time, date, location and magnitude of the
event
forecast - ANSWER a range of probability for the event
understanding hazardous process to evaluate risk - ANSWER risk =
(probability of event) X (consequences)
consequences - ANSWER damage to people, property, the environment &
economy
acceptable risk - ANSWER amount of risk that an individual or society is
willing to take
earth (plate tectonics)
- external forces on earth's surface (atmospheric effects)
- gravitational attraction (downslope movement/avalanche)
Hazard - ANSWER a process that poses a potential threat to people or the
environment
Risk - ANSWER the probability of an event occurring multiplied by the
impact on people or the environment
Disaster - ANSWER a brief event that causes great property damage or loss of
life
Catastrophe - ANSWER a massive disaster
More likely to be catastrophic - ANSWER tsunamis, earthquakes, volcanoes,
hurricanes and floods
less likely to be catastrophic - ANSWER landslides, avalanches, wildfires,
tornadoes (affect relatively smaller areas of population)
Magnitude- Frequency Concept - ANSWER - the impact of a hazard is a
function (relationship between two variables) of both its magnitude (i.e., energy
released) and frequency
- an inverse relationship
- as one goes up, the other goes down
Geologic Cycle - ANSWER throughout earths 4.6 billion year history the
materials on or near the surface have been created and modified by physical and
chemical processes
- tectonic cycle, rock cycle and hydrologic cycle
,Tectonic Cycle - ANSWER - involves the creation, movement and destruction
of tectonic plates
- new land is formed at mid-ocean ridges and land is destroyed at subduction
zones
- process is driven by earths internal energy
tectonic plates - ANSWER large blocks of the earth's crust that form its outer
shell
14 plates
Earth's Internal Structure - ANSWER - inner core is extremely hot and solid
- asthenosphere (upper mantle) is composed of hot magma with some flow
- lithosphere is a thin and brittle crust
Plate Tectonics - ANSWER - crust is broken into fragments
- movement of the plates is caused by convection currents within the mantle
- plate boundaries do not match with continents/oceans
types of crust - ANSWER - oceanic: dense, thin (averages 7km thickness)
Continental: relatively buoyant, thick (averages 30 km thickness)
whichever plate is more dense is the one that is going to sink
types of plate boundaries - ANSWER divergent, convergent & transform
Divergent Plate Boundaries - ANSWER - plates move away from each other
- new land is created
- results in seafloor spreading and causes oceanic ridges to form (e.g., Mid-
Atlantic Ridge)
Convergent Plate Boundaries - ANSWER - plates move towards each other
- collisions involving oceanic and continental crust result in subduction zones
(dense ocean plates sink and melt, melted magma rises to form volcanoes)
- collisions involving two continental plates result in collision boundaries
(neither plate sinks, tall mountains tend to form i.e., Himalayas)
Transform Boundaries - ANSWER - plates slide horizontally past each other
- zone along which the movement occurs is called a transform fault
- most located beneath oceans
, Hotspots - ANSWER - found away from plate boundaries, where magma rises
from mantle
- magma erupting at the surface results in the formation of volcanoes
- string of islands are indicative of a hotspot (i.e., Hawaii)
Rock Cycle - ANSWER a rock is an aggregate of one or more minerals
refers to a group of interrelated processes that produce the 3 different rock types
Hydrologic Cycle - ANSWER the movement and exchange of water among
the land, atmosphere and oceans by changes in state
- solar energy drives the movement of water among the atmosphere, oceans and
continents
Residence time - ANSWER the resident time of a water molecule ranges from
days in the atmosphere to thousands of years in the ocean
Hazards can be understood - ANSWER - scientists observe a event and form
possible explanations
- then a hypothesis is formed
- data is collected to test hypothesis
- knowing the cause allows for the identification of where hazards may occur
- knowledge of past events aids in predicting future events
prediction - ANSWER a specific time, date, location and magnitude of the
event
forecast - ANSWER a range of probability for the event
understanding hazardous process to evaluate risk - ANSWER risk =
(probability of event) X (consequences)
consequences - ANSWER damage to people, property, the environment &
economy
acceptable risk - ANSWER amount of risk that an individual or society is
willing to take
