Climate
Climate = Sum of weather over time + nature of seasons + possible range & extremes
describes its T, humidity, precip., wind, storm types
Controls on Climate: Latitude = amount solar energy
Altitude
Proximity to water
influence of ocean currents
proximity to orographic barrier
proximity to high- and low-pressure zones
composition of atmosphere: greenhouse gases, particulates, con-trails
city-heat island & albedo
How does plate tectonics control climate?
Koeppen's climate classification: based on ave. monthly & annual T; total monthly & yearly precip., etc
distibution of vegetation indicates climate
Glaciations: geologists have reconstructed an approximate record of global climate for geologic time.
Cooling starts in Oligocene.
Mesozoic, esp K, called “wall-to-wall” Bahamas
Global glaciations in Ptz
Global climate history: icehouse & greenhouse
Formation of Earth’s Atm
*meteors, comet impacts + Volcanic outgassing & recycling
Hadean & Archean atm: CO2, H2O, N2, CH4, NH3
CO2 deposited in carbonates --- as continents form
Then add O2 via bacteria --- cyanobacteria
O2 first combined with Fe dissolved in oceans to make BIFs
Then accumulated in air
Changes in Atmosphere Composition
Global Ice Climate “snowball”
Drop in CO2 --- spread of photosynthesizing cyanobactera & appearance of lichens
--- increased continents --- more weathering
Drop in methane --- bacteria
Additional H sulfide --- volcanic activity
Ptz tillite, Utah; Ptz dropstone, California
No glaciations for a couple 100 million years
Ordovician ice age; Gondwana moves over pole
No glaciations for a couple 100 million years
Late Paleozoic: Mississippian to Permian, glaciers grow in Gondwana, global sea level drops
Glaciation related to development of seeds & spread of plants; lots of coal
No glaciations for about 300 million years
@endK: @south pole, but warmed by ocean current
-Australia rifts away, moves North
st
-cold current encircles Antarctica – 1 sea ice – cold water sinks, moves N as deep sea current
- then: Antarctica starts to grow glaciers
India hits Asia, c60Ma, Himalayas; lots of rock exposed to weathering reduces CO2
Also rifting in north – opens Arctic ocean to Atlantic
Glaciation in northern continents
starts Pliocene, ends c10000 yrs ago; max ice reaches over 3000m thick, lots evidence of extent etc.
Caribbean: the isthmus that changed the world
Pliocene: formation isthmus of Panama by subduction; shifts Gulf Stream, more moisture to north, glaciers
The Natural Carbon Cycle & Climate
In the carbon cycle, carbon transfers between several near-surface reservoirs including the ocean, the atmosphere,
organisms (living and dead), and rocks.
Volcanic eruptions expel greenhouse gases, esp CO2
Abundant volcanism associated with the rifting of Pangea may have contributed to the Cretaceous greenhouse.
Volcanic CO2 rescued Earth from the global glaciations. (Volcanoes also put out ash & Soxides; so cool climate in
short term.)
An increase in volcanic emissions can reduce sunlight penetration into the atmosphere by increasing the
atmospheric reflectivity (albedo). Tambora put so much aerosol in the atmosphere that 1815 became known as the
“year without a summer”
Carbon is removed from the cycle for long periods of time when stored in limestones, fossil fuels (coal and oil),
organic shales, and methane hydrates
Formation of sedimentary organic deposits like coal, oil, and natural gas removes CO2 from the atm by placing C in
deep, long-term storage reservoirs. The removal of large amounts of organic C during coal-forming era in the Late
Pz (Carboniferous), coincided with pronounced global cooling.
C is removed for short periods of time when stored in organic matter (trees, animals).
The appearance of lichens in the Late Ptz may have decreased atm CO2 leading to icehouse conditions
C is returned to the atm by biotic respiration, burning organic matter, metamorphism of carbonate rocks, and
degassing from the oceans
The role of greenhouse gases: Most of incoming visible light from the Sun penetrates the atm and warms Earth’s
surface. This absorbed energy is released from the surface as infrared (thermal) energy.
Certain gases (H2O, CO2, CH4, N2O, and ozone, CFCs) in Earth’s atm absorb thermal energy and reradiate it,
warming the lower atm. This is called the greenhouse effect because it traps heat like glass in a horticultural
greenhouse.
Without greenhouse gases, Earth would be frozen. Water is the most important natural greenhouse gas, followed
by CO2. Any process that increases the amount of greenhouse gases warms the atm. Any process that removes
greenhouse gases cools the atm.
Studying past climates, paleoclimatology
Certain sedimentary strata are deposited in climate-sensitive settings.
Glacial till (tillite) indicates a cold, continental setting
Coral reefs indicate tropical marine conditions
Paleontological evidence: Example – spruce pollen vs grass pollen
Spruce: colder; grass: warmer
Spruce forests grew much farther south 12,000 yrs ago
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Oxygen isotope ratios indicate temperature of past environments. Use O and O.
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O water evaporates faster than O water. During ice ages, the O water was trapped on land as glacial ice.
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Seas then become O depleted and O enriched (the O/ O ratio increased). Shells grown in this sea water
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preserve the O/ O ratio. The oxygen isotope record is read from glacial ice (left) and fossil shells in sediment
(right).
Ice-cores
Bubbles trapped in ice cores = atmosphere at the time the ice formed. Ice cores contain annual layers that can be
readily dated.
Tree growth rings can be easily dated. The ring thickness reflects climatic changes. Wetter and warmer conditions
generate thicker rings. Drier and colder conditions produce thinner rings. In temperate zones. The sequence of
alternating thick and thin rings forms a time sequence that can be matched with other tree data. Overlapping
sequences yield a time scale.
Historical archives contain records of floods & droughts that can help assemble a climate history, a tiny way back.
Human Impact on the Earth System
Prehistoric humans had a very small impact. Today, however, humans are a powerful force of planetary change,
rivaling or exceeding some natural processes. We are now the major force that alters the landscape.
Humans have exponential population growth. They have changed & continue to change land, sea, air.
Human changes occur faster than organisms can adapt, destabilizing established ecological balances, causing
extinctions & changes.
Human-induced ecosystem destruction = deforestation, overgrazing, agriculture, and urbanization.
Rainforest decline is largely the result of human agency.
Dramatic conversion of landscape use
Human sources of greenhouse gases = fossil fuels, industry, cement
Can’t see CO2
Natural sinks that remove CO2 have been overwhelmed by anthropogenic additions since ~1900.
Computer models do not predict equal warming everywhere. The greatest impact is predicted to be in the Arctic.
Both northern & southern hemispheres show warming.
Human greenhouse gas emissions have steadily increased since the start of the industrial revolution.
The current value of 390ppm is beyond the range of natural variation for the last 800,000 years.
In 1958, CO2 was ~315ppm; in 2010, it had risen to ~390ppm. Measuring CO2 in glacial ice, was only 280ppm in
1750.
Accords: 550ppm CO2
The annual oscillation reflects CO2 removal by plants in the northern hemisphere summer.
Know CO2 is from burning fossil fuels.
Consequences: disappearing arctic sea-ice
Atm CO2 increase causes warming, but has warming taken place over the last 200 years? Thousands of published
observations suggest that, yes, it has. AAPG says, yes.
Large ice shelves, like the Larson B along the Antarctic Peninsula, are breaking up.
The snowline indicates that melting of the Greenland ice sheet is accelerating.
Valley glaciers worldwide have been retreating rapidly. The Muir Glacier, Alaska, retreated 12km between 1941
and 2004.
Melt, sublimate, less snowfall.
On a global basis, about 100 cubic miles (400 km3) of glacial ice melts every year. The cumulative decrease is
highly visible.
Measured values of near-surface ocean water temperatures are rising. Warming & more acidic oceans.
The predicted effects of global warming include a shift in climate belts and vegetation zones.
Models predict that the amount of precipitation across North America will be different a hundred years from now.
More forest fires
Modify the climate latitude of states. Albuquerque will hit 130-140F by 2100.
More health-threatening heat waves (days above 32C or 90F). #of days above 32C (90F) compared to the recent
past.
Rise in sea level due to water from disappearing glaciers. Additionally, warming causes water to expand.
Sea level has risen by about 120m (400ft) since the last glaciations.
Tide gauges document a steady rise in sea level over the last 130 yrs
Many people live within a meter of sea level. A sea level rise of 1 or 2m could inundate portions of the world where
20% of the human population lives.
Global warming may generate stronger storms. Higher sea surface temperatures lead to greater evaporation,
greater differential pressures, and a more vigorous hydrologic cycle.
Warming might lead to interruption of the oceanic circulation system. Warm water moves poleward to replace polar
deep water. Disrupting the fall of polar water may idle warm return flow. Salinity in N.Atlantic declining since mid1960s.
Melting of permafrost: already happening, bubbles of methane in Siberian lakes (from methane hydrates).
A lot of ecological effects
Remember: climate change too fast for adaptation.
How fight global warming?
Create less CO2
Renewable Energy, nuclear energy, replace coal with natural gas
Plant trees; reforestation – unsuccessful, & not enough, even if worked
Can’t burn more biomass: produces less CO2 than coal but more black carbon particles
Conservation: high gas mileage cars, build green, green renovation
“Distinct lack of urgency in gov’t approaches” (Nature, 2006)
Double coal-fired capacity by 2030, but doubt any CCS by 2030
Scrub CO2 from flue, use amine solution, then release CO2 with heat, requires $$ & is very large
Integrated gasification combined cycle (IGCC), “clean coal”, fewer S oxides & some other pollutants too, costs more
only 2 in US (+2 in Europe)
Both drop efficiency for 40% to 30%
Use CO2 (Use to mine CO2 still do…)
Enhanced oil recovery, refrigeration, carbonation, etc
Storage experimental only a few places must have: cap rock & will need to be monitored, forever
Probably will need all: oil & gas reservoirs, deep formations with salt water, deep coal beds, organic shale
Cap & Trade: “won’t make much of a dent” (Technology Review, 2009)
In Europe, Emission trading system, prices so low, companies just stay with coal
Put SO2 in clouds or particulates to reduce sunshine & make the earth cooler
CO2 capture from atm: right now – very costly; CO2 diffuse – need to move a lot of air!
Energy Sources:
USA energy use: mostly fossil fuels, much wasted
Each source has advantages and disadvantages
FOSSIL FUELS: oil - forms from bacteria; coal - forms from plants
DISADVANTAGES OF FOSSIL FUELS
1) limited resource, unevenly distributed
2) buried
3) refining necessary
4) energy via combustion - releases >125 kinds of combustion products (air pollution)
for electricity - burn ----- heat -------- steam (uses water) ------------- spin turbine
SOx = colorless, odorless, damages lungs
combines w/water --- acid rain
CO - colorless, odorless, potentially lethal
CO2 - colorless, odorless, greenhouse gas
HF - from coal
NOx - brownish, irritates eye-nose-throat,
damages plants
*** decreases visibility
+ combines w/Oxy to form ozone:
kills plants, damages eyes & respiration
particulates - lots different kinds, incl. heavy metals: Pb, Arsenic
worst = v. fine <2.5 um enter lungs and deposit the
radioactivity & toxins there
***decreases visibility associated w/health risks - lung diseases
- need these resources for other uses
Advantages? available - but not cheap!
known technology
BIOMASS BURNING: renewable supply but air pollution
HYDROELECTRIC POWER
= power from falling water requires a Dam
Advantages: No combustion so no air pollution and no greenhouse gases no mining except to make dam
Disadvantages: Damage to river system & ecology limited lifetime hazard: earthquakes loss of beauty/history
of canyon
NUCLEAR POWER
U occurs naturally in some igneous & sedimentary rocks
Fission Nuclear Power = power from splitting the atom
if & only if close together n + U235 Fission products + 3n + HEAT ----- Electricity
Advantages: NO BURNING so no air pollution, and no greenhouse gases Very efficient -- less mining, less
transport...
Disadvantages: storage of radioactive waste requires some mining of fissionable material
For your reference: PERSONAL RADIATION DOSE
NATIONAL AVERAGE: 362 millirems/year + for altitude: +35mr from our rocks: +90mr from radon in our area:
+200 (ave.)
from our food/water: +40mr
so rough estimate for El Paso: 727 mr/year
Is higher, if: you fly
if: you smoke +870 mr/year for 1 pack/day
if: live in adobe house
if live near nuclear power plant: +0.01 mr/year
if live near coal fired power plant: +0.03 mr/year
Fusion Nuclear Power = power from combining atoms if close together & very hot (millions ºC) HT + HD He + n +
HEAT
Disadvantages.: confinement - expts w/lasers, magnetic field
GEOTHERMAL POWER = power from earth's internal heat --- steam occurs naturally in volcanic areas
Hot Dry Rock project
potential danger to water supply
SOLAR POWER photovoltaic cells ----- electricity
solar panels/tanks ------ hot water
passive solar ---home heat/cooling
WIND POWER ------ electricity
Disadvantage: (some mining) Cost borne by homeowner for industrial use: needs lots of land wind power
generation is noisy
Insolation = amount of sunshine received
FUEL CELLS =power from chemical reaction that creates current
Disadvantage: presently costs more some pollution
Meanwhile: CONSERVATION
for more information - see interesting websites listed on this website
MINERAL RESOURCES
Resources = non-renewable, U.S. imports much of it, will run out of Al, Cu, Fe, Zn, Pb in your lifetime
see Mineral Information Institute for estimates of how many resources we use
ORE = desirable metal source, concentrated, recoverable
ore grade = F(concentration, current price, available technology)
How do ores become concentrated?
Igneous Processes - magmatic differentiation
Metamorphic Processes- hydrothermal alteration
Sedimentary Processes - chemical precipitation, erosion, sorting by density
Igneous Processes - magmatic differentitation via fractional crystallization
last crystals to form, associated w/felsic
[figure]
chromite, associated with ultramafic
pegmatites, large crystals
sources of Li, tourmaline, +
sulfides,
Metamorphic Processes - hydrothermal alteration
also from deep circulation of groundwater = Mississippi Valley Type (MVT): Pb-Zn
black smoker, sulfides
Sedimentary Processes
- chemical precipitation: BIF = dissolved Fe in oceans + newly produced oxygen;
Mn nodules: precipitation on deep seafloor
-weathering & erosion: removes more soluble minerals, concentrates bauxite, hematite
-secondary enrichment
Santa Rita district
sorting by density: placer deposits
Diamonds: high T & high P minerals, made in igneous rocks (mainly), often in placers
Gold - often in igneous rocks & placers
Ore exploration
Knowledge of area's geologic history, look for ORES @ modern & ancient tectonic boundaries & hot spots
+ find associated minerals/chemicals + evidence of high density --- gravity surveys+evidence of high magnetism --magnetic surveys
Other Resources: non-metallic
Dimension or Building stone: granite & other igneous; marble & limestone; flagstone (sandstone)
"Artificial stone" - cement, concrete, bricks, glass, drywall, plaster...
Environmental costs
Rock don't want = tailings, landslide risk
huge holes = weathering releases sulfuric acid, toxic chemicals
smelting = air, water, soil pollution, toxins, Heavy metals, slag piles
Geologic Hazards: Floods
Causes: rain (snowmelt), dam failures, channel switch, ice-jams
El Paso, 2006
Est. $450 million damage: $286 million to repair flood gates, floodplains, channels…
A year’s worth of rain in 2 days in many places
Dr DiGiovanni tries to go home
Mesa Hills Drive becomes a river, car becomes a clast
Further up the Franklin mts – look at the size clasts!
River flows down and over road, undercuts bank & erodes road edge
Shadow Mtn becomes a braided stream – notice the gravel bars & multiple channels
Pavement: changes infiltration, increases flooding
Infiltration rate: sands >0.8 in/hr; silt-loam 0.2-0.4in/hr; clays 0.04-.2 in/hr
st
Colorado 2013: CO warm & dry begin Sept; then rain; 1 saturate soil; heavy rains begin, 8” in Boulder+
1000 year event meaning 1 in 1000 chance
Boulder esp vulnerable: river in town, has had 8 floods in town over last 100+ yrs, in Spring
Sept usually gets 1.61”
River Discharge (Q) peak on S.Platte: 50,000cfs; 25,000% of average, heavy rains in mtns at same time as in
th
lower elevations, On Sept 12: 6000cfs in Boulder Creek, 10,000% of average; “normal” on Sept 9
What happened to all that water? Did it end the drought?
Can floods be controlled?
Most common: artificial levees, but can lead to increased flooding elsewhere
Flood control Dams: also used for irrigation, power, recreation, water supply, $$
Channelization: advantages: control floods, settle boundaries; disadvantages: increase floods downstream. Also
straighten meanders: increase erosion (water faster), more erosion downstream
Don’t build in flood zones: some areas in 1993 floods not resettled
Groundwater Hazards
Subsidence, overuse, pollution
Groundwater Hazard: Subsidence
Water pumped out, water pressure decreases, overburden weight transferred to sediments, compaction
**thick unconsolidated sediment; ex., Houston-Galveston 1.5-3m subside, 78km2 flooded
Here underlying rock is carbonate
Groundwater Hazard: Overuse
High Plains or Ogallala Aquifer, helped end the Dustbowl; tapped by >170,000 wells, feeds the breadbasket
Evap + transpiration > natural recharge
“groundwater mining”
NE NM, can’t use Ogallala anymore, must go deeper; use Entrada, when that is used up?
Groundwater Hazard: Pollution
many sources; often not recognized until damage occurs
sewage is most common: septic tanks, leaking pipes, animal containment
IF just the right flow rate & grain size
In 1940s, sewage treatment plant used this fact, needs well-sorted, porous sand & gravel to work
But creates sewage plume
Grain size?
Gravel to muds, poorly sorted
Saltwater contamination
Saltwater heavier than fresh, if pump fresh too fast, get saltwater, problem on coasts & in EP & in Chicago
Cambrian age marine depos --- salt, pump in water from Lake Mich
Pollution cleanup is possible, but expensive
Cheapest: stop using that well
Most remedial strategies include removing the source.
Pump & treat, volatilize & vaporize, steam clean, inject below drinking water level
Bioremediation utilizes bacteria to clean groundwater
Rocky Flats, largest quake M4.3
Contaminant characterization is needed for cleanup
Monitoring wells are installed to assess flow behavior, chemical testing for amt contaminants
Remedial strategies are designed to reduce health risks
Best prevented by managing land uses
Landfill with clay & plastic liners, double-lined undergrd storage tanks,
best management practices reduce contamination
esp important in wellhead protection areas
Mass Wasting Lecture:
(Return to Index)
MASS WASTING = movement of material downhill w/o a transporting agent due to gravity
Why study landslides?
Slope stability: driving force vs resisting forces
slope's shear strength = ?
Factor
Stable
Unstable
Slope Gradient
horizontal or gentle
steep
Local Relief
low
high
Load
light
great
Planes of
weakness
perpendicular
parallel
Rock Type
unfractured granite, gneiss,
...
more shear strength
•sedimentary esp., w/clay, slippery
•lots of fractures
•weathered
less shear strength
dry
lots of water
increases load, which increases driving force and
decreases shear strength
Climate
warm
vegetation
lots vegetation, increases
shear strength
cold
frost wedging and frost heaving
decrease shear strength
little
Trigger
Short, sharp shock = earthquake or impact
undercutting
Slope modification: decreases slope's resisting force
Increase Load: increases driving force esp. by adding water (also decreases shear strength)
volcanic eruptions, building
Classification of Mass Wasting split into 2 groups based on how moves: Slope Failure & Flows
SLOPE FAILURES: slump, slide, fall (talus)
FLOWS, split into 2 groups based on whether requires water or not:
esp.
example:
Slurry Flows: supported by: water pressure
Granular Flows: supported by: grain impacts
= solifluction: a few cm/yr
= creep, also a few cm/yr
debris flows incl. mudflows (lahars)
earth flows 1 m/day to 360 m/hr incl. Liquefaction
DEBRIS AVALANCHE
DEBRIS AVALANCHE: • travel long distance • sudden stop (jigsaw puzzle blocks) • fast • huge • rock
layers in order, not turbulent
ex., Blackhawk, CA
theories: • lubricate the base
• air-cushion hypothesis
• concentrated grain impacts
Hazard Assessment
• evidence of movement: disrupted ground, bent trees, etc. • slope analysis of risk • happened before?
breccia layers?
Hazard Mitigation
decrease water --- decrease Load
increase Resisting Forces
Catchment
Dam
Warning System
Review all done as exercise
Volcanic Hazards
Buried by Vesuvius eruptions, most of Pompeii not excavated
the ash layer here is about 25m thick, excavation exposes Roman columns
Shield volcano: long-lived --- large; low silica lava, fluid lava --- low slope <10
Hazards: volatiles, to structures, landslides
Volatiles and aerosols (vog)
respiratory problems
volatiles: some poisonous (H2S) or suffocating (CO2)
Lake Nyos, Cameron, 1986 – overturned & released CO2
moved down valleys as underflow; suffocated 1742 people, 6000 cattle
Lava flows – mostly from basalt
may completely destroy immovable objects: trees, towns, roads etc
rare for lava flows to kill people: usually warning & lava rarely fast
sometimes, people watching lava flows are killed
Landslides: Cape Verde
Gases readily escape hot fluid basaltic flows, producing lava fountains. Although often spectacular, these features do not
cause great loss of life or property. (Tarbuck and Lutgens, 2014)
Cinder Cone: short-lived --- small; layers of pyroclastic materials --- symmetrical, steep slope, 25-35 angle of repose
Paricutin, Mexico
Hazards: volatiles, pyroclasts, lava, local only
Composite cones or stratovolcanoes: long-lived – large; symmetrical; steep slopes – pyroclastic flows + lava flows
made from high silica (60-70%) magma = intermediate to felsic, forms andesite & rhyolite (granite), very viscous
Most dangerous
pyroclastic flows (nuee ardante or fiery ash clouds) high speed, toxic, suffocating
landslides: steep slopes + moisture + unstable rock + earthquakes
Pyroclastic flows
extremely fast (100 – 300km/hr) on a carpet of air
hot (500-1000C) kill all they touch
flatten buildings & forests
Falling ash & lapilli (ash <2mm; lapilli = pea- to marble-sized; tephra = unconsolidated, any size
bury landscapes, killing plants & crops; tephra is heavy, it cuases roof collapses
tephra is gritty; it abrades car & airplane engines; floodwaters easily move tephra as deadly lahars
Lahars = debris flows = water + ash; water-supported slurry flow
Nevada del Ruiz, Colombia, buried Armero w/over 25,000 people (see No Apparent Danger)
Tsunami
Krakatoa – between Java & Sumatra; large eruptions in Summer, 1883
On August 27, 1883, at 10AM the island gone; magma chamber breached by ocean; island blown up; tsunami killed
36,000 people
Mass extinction
Flood basalts: associated with 2 large mass extinctions (2 of the Big 5)
end Paleozoic: largest ever, 95% death rate; & end Mesozoic: asso w/large impact, wiped out dinos & more
Mitigating volcanic hazards
Prediction of volcanic eruptions: volatile composition, earthquakes (volcanic tremors), changes in shape (tiltmeters or
GPS), geologic history
only ~10% of 1300 active volcanoes monitored
Fumaroles – volatiles, clues to future eruptions
Galeraus erupts
Planning: danger assessment maps; areas of pyroclastic flows, lahars, landslides
Evacuation: Mt St Helens: saved hundreds (were out for >2 mnths); Mt Pinatubo, thousands;
sometimes eruptions don’t occur, large expenses
Diverting Lava: explosives, heavy equipment, seawater for weeks
Volcanoes & Civilization
Humans and volcanoes have coexisted for millennia; both bad & good facets
volcanic soils highly fertile; civilizations have prospered & been erased: Minoans – Santorini
Volcanoes & Plate Tectonics
data: most volcanoes (& quakes) at plate tectonics; different magma at different boundaries
@divergent boundaries
partial melting of upper mantle (lower crust) [type of magma differentiation]; due to release of pressure + rising mantle
formation of ocean crust; *shield volcanoes, fissure eruptions
Convergent margins w/subduction
pressure increases + amt water increases + small T increase – partial melting of crust & upper mantle – intermediate to
felsic composition magmas – andesite & granite --- composite volcanoes
continent crust made; ocean crust destroyed
Hot spot volcanics: ex., Hawaii (intraplate volcanism)
rising mantle plume: T increase – mafic volcanic – shield volcanoes & fissure eruptions
under continents: felsic volcanic (plume melts part crust) – super-volcanoes & hot springs, ex, Yellowstone
Earthquakes
Plate boundaries: locations on Earth where tectonic plates meet; ID = concentrations of earthquakes, associated with
many other dynamic phenomena
Most earthquake damage = ground shaking, primary damage
Secondary damage: fire. Easy to start, hard to put out; fire triggered when a gas line ruptured during the 1994 Northridge
quake in southern California
Secondary damage: mass wasting. Shaking is a common trigger.
Secondary damage: liquefaction. This tilted building rested on unconsolidated sediment that behaved like quicksand
during the 1985 Mexican earthquake.
Secondary damage: tsunami. Next week
Hazard. Mapped to assess risk and develop building codes, implement land-use planning, and disaster response
amount of damage depends on: Determine from paleoseismology – magnitude, distance from focus, length of shaking;
fundamental period of building (resonance = collapse); building strength (flexible frame, bolted to foundation); Map: local
geology (rock type, basin geometry)
also study faults – how much energy do they store?
Map – find the fault, fault active? how often does it go? How strong?
Prediction: study geologic record, determine average frequency & strength of past quakes
Turkey just starting to build for quakes (one bldg, a tunnel, etc)
Map rock type: landfill behaves like soft mud, water-saturated is worst
Determine basin geometry
Paleoseismology: extend record back
Trench – offset soil or peat layers, sand flow layers (liquefaction)
Trees – severe damage, growth slows for years after
Use archeologic evidence: Susita, sea of Galilee, columns toppled by 749AD earthquake, columns parallel
Crusader fortress of Metzad Ateret, damaged in 2 quakes
develop risk maps
Landers in 1992, Northridge in 1994, has increased stress on San Andreas
Use for long-term predictions
Study active faults. Colors = electrical resistivity; warm – more pore fluids, creep; white dots = minor quakes, blacksamples, incl talc
aseismic slip found by comparing 2 scans
Immediate prediction
Study precursor events: foreshocks, radon gas release (Kobe), microwaves (Loma Prieta), drop in well levels
problem: pattern erratic/unreliable, fault may be buried/unknown, each segment needs to be instrumented
cluster analysis: promising
Construction design: building floors “pancake”, bridges and roadways topple, building supports crush, masonry walls
break apart
TAP: took 2002 quake with 4.3m of displacement, no damage
reduce amount of shaking: base isolation, counterweights
Earthquake preparedness (kits) & drills. Educate individuals on safe behavior & responses to earthquakes
Individual – look around for risks, bolt large objects down, if smell gas, turn it off
Kits: for home, car, work; also incl: tarps, walking shoes, evacuation clothes, radio; store in safe locations
During the quake: won’t pay for natural hazards, experts don’t recommend running outside
Warning system: P wave arrival – radio waves are faster, used in Japan to stop high speed trains, in CA – to move
emergency vehicles
Tsunami
Earthquakes, landslides, caldera fm, or impacts can spawn devastating tsunamis; December 26, 2004 – Indian ocean
tsunami; March 11, 2011 – eastern coast of Japan
Landslides
Tenerife has had 6 in last several m.y. Could send tsunami to our E coast
many slumps surround the Hawaiian islands. The steep cliffs (above) are the head scarps of huge slumps. Largest
active ~10cm/yr, becomes fast every 100,000yrs+
massive debris flows = can cause tsunamis
Caldera fm: recall Krakatau & Santorini
Impact deposits
The 2011 Tohoku-Ohi tsunami destroyed the northeast coast of Japan. Magnitude 9.0 earthquake was 130km offshore
Tsunami waves began to arrive in 10min, in some cases erasing entire villages
Wave heights reached >20 feet along coast of Japan & tsunami warnings were issued as far away as the west coasts of
the US & South America
The Fukushima nuclear power plant was inundated when 14m of water breached the seawall protect the plant. Hydrogen
explosions destroyed the reactor buildings
NATIONAL AVERAGE: 362 millirems/year + for altitude: +35mr from our rocks: +90mr from radon in our area: +200
(ave.)
from our food/water: +40mr
so rough estimate for El Paso: 727 mr/year
Is higher, if: you fly
if: you smoke +870 mr/year for 1 pack/day
if: live in adobe house
if live near nuclear power plant: +0.01 mr/year
if live near coal fired power plant: +0.03 mr/year
Surviving a tsunami
(interviews with survivors): many will survive the quake, heed natural warnings, heed official warnings, expect many
waves, head for high ground & stay there, abandon belongings, don’t count on the roads, go to an upper floor or roof of a
building, climb a tree, climb onto something that floats, expect the waves to leave debris, expect quakes to lower coastal
land, expect company
Trees = tsunami protection or Tsunami walls
Tsunami warning network: a tsunami warning center in Hawaii tracks Pacific quakes and issues alerts if a tsunami is
possible; tsunami detectors on the deep sea floor sense pressure increases from changes in sea thickness
Hazards from Space
Impacts: velocity = 12-72 km/s, compare to rifle bullet ~1.5km/s
Impact on Moon: crater ray, discontinuous ejecta, central peak, secondary crater chain, continuous ejecta
On Earth have <200 impact craters – most subducted, weathered, buried, ….Meteor Crater, Manicouagan, Chicxulub,
Vredefort
Manicouagan: Quebec, Canada, 100km dia, 215mya, end Triassic may have contributed to a mass extinction
Vredefort: oldest one known on Earth, 2298 my; now only about 40km, was probably 300km (based on shock meta
effects) largest, related to preservation of Au in Witwatersrand
Meteor Crater, AZ, 49,000 yrs old; small, but recent (& cute)
comet nucleus (?) impact producing Chicxulub ~65mya + flood basalts (Deccan Traps) = mass extinction
impactor about 10km across; gravity map shows extent, buried beneath later LS
Most large (>1km) asteroids known {near Earth asteroids}; asteroids are usually too small to see; 75% are dark
Analysis of Meteorites: 3 broad categories: Iron, Stony, Stony-Iron. Irons: dense, have irregular surface;
Stony: often fusion crust from melting in Earth’s Atm; Stony-Iron: polished view, mix of Fe & rock
Iron: polished & etched, shows xls; Carbonacous chondrite w/chondrules & volatiles, make it very dark
Orbits of some near-Earth objects (NEO) are shown in blue; Earth is hit by a 1km object every few 100,000 years, by an
object >6km every 100 my
Earth’s little buddy – 200km wide; asteroid same general path as Earth, not a threat – is ahead of us & closest approach
is 20 million miles
Track of asteroid Apophis, near miss in 2029
Chelyabinsk 2013. Tunguska 1908
Origins of Meteorites: planetesimals cool & differentiate (why we have 3 kinds); collisions eject material from different
depths with different compositions & temperatures --- asteroids
Comets – tail of ionized gases (CH4, NH3, CO2, water), tail composed of dust
Meteoroids contributing to meteor shower are debris particles, orbiting in the path of a comet; spread out all along the
orbit of the comet; comet may still exist or have been destroyed
The big 5 mass extinctions (Chicxulub, Manicouagan)
Hazards from Supernovae
the Shocks of supernova remnants accelerate protons & electrons to extremely high, relativistic energies
protection: solar wind + magnetosphere + atmosphere
Gamma Ray Bursts (GRBs): short (~a few s), bright bursts of gamma-rays; probably related to the deaths of very
massive (>25 Msun) stars; could destroy ½ ozone layer
Solar Flares
intense radiation – mag field suddenly rearranges, lines open up over magnetic poles = sunspots
problem for high frequency radio communications
Large solar flare in 2003: preceded by Coronal mass ejection – send electrically charged gas to Earth
Can: cause satellites to lose altitude by increasing their drag; induce currents in power grid; degrade accuracy of satellite
navigation (GPS etc)
Solar Flare, Jan 2005 = most intense burst of radiation in 50 yrs, “proton shower”
The Extreme UV imaging telescope on SOHO shows the flare erupting, then the camera getting peppered by solar
particles soon after
SOHOs instrument blocks out the corona to watch the coronal mass ejection streaming out into space
the solar flare tripped radiation monitors all over the planet & scambled detectors on spacecraft within minutes. It was an
extreme example of a flare with radiation storms that arrive too quickly to war future interplanetary astronauts.
After flare, a storm of energetic protons (makes gamma rays) impacted Earth just 15 minutes later as opposed to the
usual timeline of a few hours.
DSCOVR satellite, launched 2015
Deep Space Climate observer connected to NOAAs Space Weather prediction center
MASS WASTING = movement of material downhill w/o a transporting agent due to gravity
Why study landslides?
Slope stability: driving force vs resisting forces
slope's shear strength = ?
Factor
Stable
Unstable
Slope Gradient
horizontal or gentle
steep
Local Relief
low
high
Load
light
great
Planes of
weakness
perpendicular
parallel
Rock Type
unfractured granite, gneiss, ...
more shear strength
•sedimentary esp., w/clay, slippery
•lots of fractures
•weathered
less shear strength
lots of water
increases load, which increases driving force and decreases shear
strength
dry
Climate
cold
frost wedging and frost heaving
decrease shear strength
warm
vegetation
lots vegetation, increases shear
strength
little
Trigger
Short, sharp shock = earthquake or impact
Slope modification: decreases slope's resisting force
esp. undercutting
Increase Load: increases driving force esp. by adding water (also decreases shear strength)
building
example: volcanic eruptions,
Classification of Mass Wasting split into 2 groups based on how moves: Slope Failure & Flows
SLOPE FAILURES: slump, slide, fall
Hazard Assessment
• evidence of movement: disrupted ground, bent trees, etc. • slope analysis of risk • happened before? breccia layers?
Hazard Mitigation
decrease water: drains, wells, etc
--- decrease Load: grade back, cut & fill, benching
increase Resisting Forces: gabions, walls, fences, tie-backs, rock bolts