GO150 Exam #1

natural hazard

natural hazard

natural process or event that is a potential threat to human life or property, or ecosystems; are repetitive

natural disaster

natural hazard that occurs over a limited time within a defined area. criteria includes ten or more casualties, 100+ people affected, state of emergency is declared, international assistance is requested

catastrophe

massive disaster that requires significant amount of money or time (resources) for recovery to occur

internal processes

come from forces within the earth, “slow” processes, powered by heat deep within the earth, drive movement of lithospheric plates (continents, the opening of new seas, closing of old ones, formation of mountain ranges)

external processes

come from forces at or very near to Earth’s surface, “quick” processes, powered by energy from the sun, drive cycles of the atmosphere (tropic cyclones, thunderstorms, snowstorms, flooding events, drought, wildfires)

5 fundamental concepts in the study of natural hazards as disasters

1. science helps us anticipate hazards

2. knowing hazard risks can help people make decisions

3. linkages exist between natural hazards

4. humans can turn disastrous events into catastrophes

5. consequences of hazards can be minimized

1. science helps us anticipate hazards

science is the body of knowledge that has resulted from investigations, observations, and experiments (use the scientific method), scientific investigation has improved understanding of natural hazards and disasters + improved ability to anticipate some natural hazards

uniformitarianism

a scientific thought pattern that the same natural, physical, and biological laws and processes that have operated on the earth through geologic time are the same laws and processes operating today and will continue in the future

environmental unity

one action causes others actions and reactions in a connected system

predicition

specific time, date, location, and magnitude of an event; use data from previous events to predict a future event, estimated probability

forecast

gives the certainty of an event in %

risk

probability of an event x consequences

consequences

damages to people, personal property, infrastructure (roads, bridges) and the environment

acceptable risk

the amount of risk that an individual or society is willing to take

4. Humans can turn disastrous events into catastrophes

densely populated areas increase the number of people at risk (more loss of life compared to hazardous events in a less dense area) and increased exposure to contaminants and pollutants.

magnitude frequency concept

frequency of an event inversely related to magnitude. size matters, location.

5. consequences of hazards can be minimized

we are primarily reactive in dealing with hazards, need to increase efforts to anticipate disasters and their effects, effects of disasters can be direct or indirect

geologic hazards

the casual factor is some type of geological process (earthquakes, tsunamis, volcanic eruptions)

atmospheric hazards

includes meteorological and hydrological events, processes operating in the atmosphere and in the water cycle are mainly responsible (tropical cyclones, floods, tornadoes, lightning, blizzards)

climatological/biological hazards

may occur naturally (wildfires, extreme temps, drought, disease epidemics)

primary effects of natural disasters

occur as a result of the process itself, directly. (water damage during a flood, collapse of building during earthquake)

secondary effects of natural disasters

occur only because the primary effect has caused them (fires being ignited, loss of power, lack of drinking water all from earthquakes)

tertiary effects of natural disasters

long term effects that are set off as a result of primary or secondary events (loss of habitat caused be floods or wildfires, permanent changes in the position of a river channel caused by a flood)

geologic features at divergent plate boundaries

mid-ocean ridges, rift valleys, volcanoes, earthquakes

geologic features at convergent boundaries with subduction

earthquakes, island arcs, volcanic arcs, deep sea trenches

geologic features at convergent-collision boundaries

mountain ranges, earthquakes

geologic features at transform boundaries

earthquakes

geological features at oceanic hotspots

volcanoes (gentle), earthquakes

geologic features at continental hotspots

volcanoes (more explosive)

divergent boundary

approx. 80% of earth’s magma is extruded through volcanoes at this, occurs when two tectonic plates move away from each other

earth’s age

approx. 4.6 billion years old

5 protective outer layers of earth

atmosphere, hydrosphere, cryosphere, biosphere, geosphere

inner core

solid metal, 750 miles wide, high density, composed of 90% iron, sulfur, and nickel, high pressure so it remains solid

outer core

liquid iron layer, 1,370 miles wide, high density, heated by the radioactive decay of uranium, earth’s magnetic field radiates from here, composed of mostly iron and nickel

mantle

mostly a semi-solid “plasticized” layer, 1,800 miles across, composed of rocks in different stages of melting and formation, sub-divided into additional layers

crust

outermost rock layer of earth, 1-25 miles in thickness, coolest layer, most brittle, least dense, divided into two types

continental crust

several billion years old, 2-25 miles thick, less dense, made mostly of silicate rocks rich in aluminum and oxygen

oceanic crust

less than 200 million years old, 1-5 miles thick, denser, made mostly of basalt rock rich in magnesium and iron

lithosphere

uppermost layer of mantle formed with the bottom of the crust and the very top of the mantle, broken into big slabs

asthenosphere

layer beneath the lithosphere

mesosphere

alternate name for the entire upper mantle layer

tectonic plates

the broken slabs of the lithosphere

convergent boundary

occurs when two tectonic plates collide together

subduction zones

the area where oceanic crust is forced down into the mantle where it begins to melt; magma rises into and through the other plate, solidifying into granite

transform boundary

occurs when two plates slide past each other, no crust is created or destroyed

conduction

the transfer of heat through materials caused by a heat source

convection

the rotation of heat within

radiation

assists in convection, the heat source that causes convection

decrease in density

as molecules move apart as a result of moving faster from becoming heated

divergent oceanic plates

most often occurs between these, results in mid-ocean ridges, new lithosphere is created, seafloor spreading

seafloor spreading

the process by which oceanic lithosphere deforms and stretches; magma rises beneath the lithosphere causing it to become hotter and thinner. the magma erupts and cools, which creates the seafloor.

divergent continental plates

rift valleys, new lithosphere is created providing ways for new seas, rifting

rifting

process by which continental lithosphere deforms and stretches away. magma rises beneath the lithosphere causing it to become hotter and thinner, magma erupts and cools creating a new lithosphere, continental plates are pushed apart and void becomes a new ocean.

O-C subduction

oceanic plate subducts underneath a continental plate; creating subduction zones where more dense oceanic plates sink (subduct) beneath less dense continental plates; volcanic arcs, deep ocean trenches, earthquakes

O-O subduction

an oceanic plate subducts underneath another oceanic plate; creates subduction zones where the more dense oceanic plates (older) subduct under the less dense plate; island arcs, deep ocean trenches, earthquakes

C-C collision

a continental plate collides with another continental plate; creates collision zones; creates orogen (folded) mountain ranges, can create subduction zones depending on rock density; occasional earthquakes

hot spots

stationary area of intense heat in the mantle that creates a plume of molten rock (magma chamber) that breaks through the lithosphere to form a volcano; intraplate; volcanoes formed as tectonic plates move over these

continental crust with hotspots

violent explosive

oceanic crust with hotspots

gentle, effusive

convection is all about

heat, density, and gravity

oxygen, silicon, aluminum, iron, calcium, magnesium, sodium, potassium

8 elements that make up 98% of earth’s crust

basaltic

rich in dense materials, one of 3 types of magma, mafic composition, lowest volatile gas contest (1-3%), highest temperature, low viscosity, mostly at divergent boundaries and oceanic hotspots, 80% volume at earth’s surface, decompression melting

andesitic

intermediate composition, intermediate volatile content, middle temperatures, mostly at convergent subduction boundaries, one of 3 types of magma, 10-15% volume at earth’s surface, addition of volatiles

rhyolitic

felsic composition, low in dense materials, highest volatile gas content, lowest temperatures, highest viscosity, mostly at continental hotspots, 1 of 3 types of magma, 5-10% volume at earth’s surface, addition of heat

viscosity

resistance to flow, depends on chemical composition and temperature