GLG110 Geologic Disasters and the Environment

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GLG110 Geologic Disasters and the Environment
Today Soils and Weathering Chapter 14
Instructor Professor Ramon Arrowsmith Email
ramon.arrowsmith_at_asu.edu Office PSF-640
480-965-3541
TA Tom Foltz Email Thomas.foltz_at_asu.edu Office
PSH-574
Course Website http//glg110.asu.edu
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Announcements

• Exam 2 fire-related questions will be extra credit

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M7.9 Denali Earthquake
Main shock and aftershocks
Tectonic setting Denali fault accommodates right
lateral motion as south Alaska moves westward
north of the Aleutian subduction zone
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The view is eastward along the main strand of the
Denali fault, which is marked here by a prominent
linear valley along the southern edge of the
Alaska Range. The magnitude 7.9 earthquake that
occurred in the afternoon of November 3, 2002 was
preceded by a magnitude 6.7 earthquake in the
early morning of October 23, 2002. The earlier
earthquake and its zone of associated aftershocks
were located slightly to the west of the later,
larger earthquake.
http//neic.usgs.gov/neis/bulletin/02_EVENTS/EQ_02
1103/alaska_map3.html
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http//wwwdggs.dnr.state.ak.us/earthquake.html
An aerial photo of the Trans-Alaska Pipeline
System (TAPS) line near the Denali fault, looking
west. This is where the line is supported by
rails on which it can move freely in the event of
fault offset. Here the line has moved toward the
west end of the rails. Alyeska Pipeline Service
Company reported no breaks to the line and
therefore no loss of oil. Note the transverse
crack on the Richardson Highway in lower left.
Out of view to the left (south) of this photo is
a 2.5 m right-lateral offset of the highway where
it crosses the fault. Photo by Rod Combellick,
DGGS.
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Trans Alaskan Pipeline "I think it should be a
note of real satisfaction for the people
responsible for the maintenance of the pipeline
that it did exactly what it's supposed to do in
an earthquake. It bent but it did not break,"
Gov. Knowles said. Oil producers on the North
Slope were being limited to 3 percent of their
normal production Tuesday, down from 5 percent
earlier, but Paul Laird of BP Exploration
(Alaska) Inc. said no wells would have to be shut
down if the pipeline flow was restored early
Wednesday. Shutdowns are expensive to the oil
companies, especially due to the combination of
hot oil coming out of the ground and the cold
conditions on the North Slope.
http//www.adn.com/front/story/2085994p-2183301c.h
tml
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The road offset in the foreground is south of the
cleared area seen in the background where the
pipeline is designed for lateral fault offset.
Photo looking north. Photo by Patty Craw, DGGS.
http//wwwdggs.dnr.state.ak.us/earthquake.html
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Pavement buckling, 7.5-foot right lateral offset
over 20-foot-wide fault rupture zone - Richardson
Hwy - Milepost 215.7. Approx. 30 inches of
vertical ground displacement across rupture zone
(south side down)
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M7.9 Denali Earthquake

• "I thought, 'Oh good, an earthquake,' and then it
  got worse and worse," he said. The quake tipped
  over a band saw and other heavy tools, his
  1,135-litre outdoor fuel tank and moved a
  68-kilogram anvil six metres across the floor.
  Schmoker said he's a big game hunter and usually
  enjoys short earthquakes. "A charging brown bear
  I can handle," he said. "This scared the hell out
  of me."
• Randy Schmoker, a metal worker in Porcupine
  Creek, was in his shop when he felt the ground
  move. (http//www.canada.com/victoria/story.asp?id
  092CFEE4-0892-4F71-A2A5-184144FB9913)

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Slide on Galcier Alaska Range
Debris flow Alaska Range
http//wwwdggs.dnr.state.ak.us/earthquake.html
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Landslide across Black Rapids Glacier. The
landslide moved from right to left across the
valley. The ridge in the center is a medial
moraine. The fault scarp is not visible in the
photo. Photo by Patty Craw, DGGS.
http//wwwdggs.dnr.state.ak.us/earthquake.html
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smaller star - location of the M 6.7
shock larger star - location of the M 7.9
shock grey circles - reviewed locations of the
M7.9 event aftershocks blue crosses - automatic
locations of the M7.9 event aftershocks green
crosses - reviewed locations of the M6.7 event
aftershocks white squares - towns and cities
yellow triangles - permanent seismic
stations red lines - mapped fault traces black
lines - roads blue lines - major rivers
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Denali Earthquake information-I

• Origin time 112PM Alaska Standard time.
• Earthquake initiated on the Denali fault in the
  epicentral region of the M6.7 Oct. 23 earthquake
  and apparently ruptured eastward (towards the
  pipeline).
• Seismic radiation pattern is consistent with
  right-lateral slip on a generally E-W trending
  rupture.
• Numerous aftershocks have been reported.

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Denali Earthquake information-II

• An eastward rupture is consistent with the
  reported road closures caused by landslides.
• This M7.9 shock is the largest earthquake on the
  Denali fault since at least 1912, when a M 7.2
  earthquake occurred in the general vicinity of
  the fault, more than 50 miles to the east of
  today's epicenter.
• Web sites
• http//earthquake.usgs.gov/eqinthenews/uslbbl/inde
  x.html
• http//www.giseis.alaska.edu/Seis/M7.9_quake_2002/
  M7.9_quake.html

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Geologic Evidence of Past Earthquakes on the
Denali Fault

• The modern fault scarp is very clear, but
  somewhat degraded, indicating that there has been
  at least several hundred years since last major
  earthquake(s) between McKinley Park on the west
  and the Richardson Highway on the east.
• In epicentral area, USGS geologist George Plafker
  observed that the last big earthquake had 6-8 m
  of right-lateral offset. Slip rate on the Denali
  fault since the last glaciation (10,000 years
  before present) averages about 1 cm/year. It
  follows that a 6-m displacement would require 600
  years of strain accumulation.

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Felt in Louisiana?

• N E W   O R L E A N S, Nov. 4 When people saw
  water sloshing about in ponds, bayous and pools,
  an earthquake more than 3,000 miles away seemed
  an unlikely culprit. "My neighbor actually
  thought there was an alligator in the pond," said
  Dan Musmanno, 51, of the New Orleans suburb Belle
  Chasse. "My neighbor's son went out there and
  said, 'It ain't no alligator.' The water was
  going back and forth for about a half hour. It
  was kind of spooky."
• "When you have an earthquake of this size, it
  generates what we call surface waves," said Dale
  Grant, a geophysicist with U.S. Geological
  Survey's National Earthquake Information Center
  in Golden, Colo. He said waves of energy travel
  through the Earth's crust and cause disturbances
  in water. (http//abcnews.go.com/wire/US/ap2002110
  4_290.html)

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The October 23, 2002 M6.7 event may have
transferred 0.1-0.2 MPa (1-2 bars) of Coulomb
stress to the M7.9 hypocenter. In other words,
the big one may have been triggered by the
earlier one. http//pasadena.wr.usgs.gov/office/ga
nderson/alaska2002/index.html
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http//wwwdggs.dnr.state.ak.us/earthquake.html
Offset crevasses on the Canwell Glacier. Photo by
Patty Craw, DGGS.
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Mud Volcano
http//sfgate.com/cgi-bin/article.cgi?f/n/a/2002/
11/04/national0449EST0446.DTLtypenews
http//www.aeic.alaska.edu/input/sigrun/sprunga2/n
orthway/northway.html
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Soils! Outline

• Introduction
• Soil profiles
• Soil properties
• Soil fertility
• Soil classification
• Engineering properties of soils
• Soil erosion
• Land use and environmental problems of soils
• Soil surveys and land use planning

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Introduction What is soil?

• Soil scientist solid earth material that has
  been altered by physical, chemical, and
  biological processes such that it can support
  rooted plant life.
• Engineer solid earth material that can be
  removed without blasting.
• Geologist uses both definitions

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http//soils.usda.gov/education/resources/surdown.
pdf
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Why study soils

• Land use planning (urbanization, timber
  management, agriculture)
• Waste disposal problems and site suitability
• Natural hazards earthquakes, flooding, and
  landslides
• Climate history (soils hold climate signal)

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Soil development

• Weathering breaks surficial materials down by
  either mechanical or chemical processes.
• Soil development is a function of climate,
  topography, parent material (the rock from which
  the soil is formed), time, and biological
  processes.

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Soil profiles
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Soil Profiles
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Soil properties

• Color
• O A dark because of organics
• B most dramatic depending on the presence of iron
  oxides, clays, and Calcium Carbonate
• Yellowish soils may be poorly drainedcould be
  unstable and hold pollutants

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Soil properties

• Texture Grain size and differences in grain
  size (sorting)

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Soil properties

• Structure soil particles cling together in
  aggregates called peds that are classified
  according to shape

Increasing age (clay content)
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Soil fertility

• Capacity of soil to supply nutrients needed for
  plant growth when other factors are favorable.
• Soil is a complex ecosystem.
• Soil development can be an important evolutionary
  control on landscape productivity.

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Landscape position, climate, time, organisms
influence soil development Date landscape,
control vegetation and landuse
http//soils.usda.gov/education/resources/surdown.
pdf
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Soil classification

• Soil taxonomy
• Soil scientists
• Physical and chemical properties
• Useful for agriculture and landuse
• Pretty complicated

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Soil classification

• Engineering (Unified soil classification system)
• Mostly based on grain size because that is a
  major control on soil strength and water
  retention/transmission properties

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Engineering properties of soils

• Strength ability of soil to resist
  deformationcohesion and friction
• Compressibility tendency to decrease in volume
• Erodibility ease with which soil can be removed
  by wind or water
• Hydraulic conductivity measure of ease of water
  motion through soil
• Ease of excavation
• Shrink-swell potential

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Water content influences soil strength
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Tree roots hold soil together increase cohesion
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Expansive soils Clay expands with water input
causing differential soil movement and structural
damage
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Map of soil shrink/swell potential in the Greater
Phoenix area
http//www.az.nrcs.usda.gov/soils/bigshrink.html
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Soil erosion depends on (USLE) Runoff Erodibility
Length of hillslope Soil cover Erosion control
practice
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Effects of land use

• Agriculture
• Urbanization
• Off road vehicles
• Soil pollution

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Soil pollution

• Occurs when materials detrimental to living
  things are applied to soils.
• Toxins may be concentrated
• May be hard to treat.

Bioremediation
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Soils mapping example
http//soils.usda.gov/education/resources/surdown.
pdf
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Agricultural application
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