Geology 112 Geologic Disasters

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Geology 112Geologic Disasters

• Instructor Dr. David M. Best
• Contact Phone [phone] or e-mail
  David.Best_at_nau.edu Please use GLG 112 in the
  subject line
• Office Geology Annex Room 203
• Office Hours 200p 300p MTTh or by
  appointment call or send e-mail

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• Textbook
• Natural Hazards, 2008, Keller and Blodgett, 2nd
  edition, Pearson Prentice Hall
• Web site
• http//oak.ucc.nau.edu/dmb25
• You should bookmark this web address

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Course Objectives

• Be able to
• examine the way in which Earth and humankind have
  been affected by natural disasters
• demonstrate how different processes at work on
  Earth are often interrelated
• use relevant information in the future to
  understand natural disasters as they occur

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Course Expectations/Outcomes

• Develop new vocabulary
• Understand processes at work on Earth that cause
  disasters
• Be able to understand why events happen and how
  their effects can be reduced
• Do well in the course and come out with an
  appreciation of the subject matter

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Course Structure

• Lecture-based
• We meet Monday through Thursday from 8am 12
  noon
• We will have two or three breaks each day
• Class participation and discussion are encouraged
• Several videos which involved in-class question
  sheets
• Read material prior to covering it in lecture
• Come to class

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Course Assessment

• Three exams total 300 points
• Multiple-choice, short essay, matching questions
• In-class exercises 50 points

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Grade determination
Points

• Three exams 300
• In-class exercises 50
• TOTAL 350
• A 90 or higher gt315
• B 80 89.9 280-314
• C 70 79.9 245-279
• D 60 69.9 210-244
• F lt59.9 lt 210

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General comments

• Metric system used in sciences
• Distances meters/kilometers
• Temperatures Celsius
• Mass/Weight gm and kg
• We will also refer to units in the US/British
  system miles, Fahrenheit

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Lets begin!

• Geology
• Greek geo Earth logos discourse
• Physical geology looks at Earths materials and
  processes
• Historical geology examines Earths origin and
  development through time
• We will examine aspects of each of these in
  discussing disasters

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Scientific Inquiry

• Hypothesis
• An untested, proposed explanation for facts,
  measurements or observations
• Example more study hours better
  grades
• Results must be repeatable with predictable
  results
• Theory
• Results from the survival of extensive
  examination of competing hypotheses related to
  the topic
• Example Theory of Relativity Theory of Plate
  Tectonics
• Principle or Law
• Scientific theories that are absolutely correct
• Example Law of universal gravitation

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Chapter 1Introduction to Natural Hazards

• Earthquakes floods typhoons
  /hurricanes/cyclones landslides tsunamis
• all these events require an energy source
• Gravity, thermal
• In 2001 12 of the 16 75 most deadly events
  involved water storms and floods
• In 2003 9 of 15 60 most deadly events involved
  water 4 involved heat related sources
• In 2005 10 of 15 67 involved water
• Cyclonic storms and earthquakes have caused the
  greatest loss of life in the past 50 years.

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• Greatest losses occurred in Asia
• Why?
• Most people
• Poor communications
• Poor construction
• Many people in low-lying areas

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• Post-event effects
• Increased suicide rate
• Disrupted life style consider areas in South
  Asia affected by the Dec 26th tsunami and the US
  Gulf Coast region after Katrina and California
  wildfires
• Economic losses
• Total annual losses are skewed by 1-2 events
  which occur in developed countries, such as the
  US
• Consider the events in New Orleans with H.
  Katrina
• Estimated at a minimum of 45 billion
• Tsunami damage (Dec 2004) had far reaching
  effects but poorer areas were affected
• Insurance sometimes helps
• Flood insurance is very risky

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• Of the top 10 most costly insurance disasters
• All occurred in past 20 years
• All were in the US
• Most costly events are quite different from most
  deadly in terms of localitieseconomics vs.
  population
• Deadliest in Asia, Peru, Iran, Europe, Venezuela
• Final accounting often delayed
• Northridge EQ in Jan 1994 initially 2.8 b rose
  to 17.3 b six years later final amount 18.5 b
• Dec 26th tsunami will take years to assess as
  will the damage caused by Hurricane Katrina
  August 2005

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Events the past month

• Wildfires in California
• Swine flu in Mexico, US, Europe
• Earthquake in central Italy

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Natural hazards

• Hazard any natural process that poses a threat
  to human life or property these are predictable
  and repetitive
• Disaster the effect a hazard produces, usually
  over a limited time period in a fairly
  well-defined geographic area.
• Catastrophe a massive disaster recovery time
  is significant, in months or years, and process
  of recovery is complex.
• Areas that are likely to have natural disasters
  but have not experienced them are considered as
  being potential
• Slopes of volcanoes or steep mountains
• Shorelines in hurricane alley
• Floodplains of rivers
• Mitigation reduction of effects or prevention
  steps must be considered
• People often reoccupy destroyed areas, making it
  difficult to mitigate future problems
• Events will occur again recurrence rates
• What about New Orleans?
• What about California?

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Fig. 1.4 Major hazards in the United
Statesblizzards, wildfires not shown
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• Average annual loss of life worldwide 150,000
• Cost 50 billion per year in terms of property,
  mainly in developed countries
• Major losses in recent years
• 1976 China EQ 255,000 deaths
• 1985 Colombia volcano 23,000
• 1991 Bangladesh cyclone 140,000
• 1999 Venezuela floods/rain 50,000
• 2004 Dec 26th tsunami 245,000
• 2005 Aug 29th Katrina 1,800
• 2008 May Myanmar (Burma) 140,000
• 2008 May China EQ 68,712

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• Examples of reoccupied areas
• Mt Vesuvius and Mt Etna Italy
• Portions of California along San Andreas fault
• Various areas in South America in Andes
• East and Gulf coasts of US
• Japan and the Philippine Islands
• Note that in most cases there is NO alternative
  place to relocate
• Impact areas change due to shifts in population,
  more urbanization, changes in the terrane
  hillslopes, drainage, vegetation

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Descriptor terms

• Magnitude
• The size of an event as measured on some scale,
  such as the Richter scale for EQs, the Enhanced
  Fujita scale for tornados, or the Saffir-Simpson
  scale for hurricanes energy related
• Frequency
• How often a specific type of event occurs
• Too many variables exist to provide any
  meaningful way to truly predict an event thought
  of as a rough average
• Large events occur less often small ones more
  often so this is an inverse relationship
  magnitude-frequency idea
• Return period or recurrence interval
• Number of years between same-sized events
• Usually the larger and more energetic the event,
  the longer the return rate
• Floods are spoken of in terms of the 100-year
  flood meaning a chance of 1 in 100 1 that the
  event occurs in a given year

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Population doubles roughly every 53 yrs Doubling
time is found by 70 divided by annual
growth So 2 growth doubles population in 35
yrs
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Understanding and assessing hazards

• We need
• Historic and recent prehistoric data
• Recurrence intervals
• Review of maps and aerial imagery
• Review of stream deposits, when appropriate
• Current geologic conditions
• Events are termed hazardous only because weve
  chosen to develop in areas affected by natural
  processes, e.g., floodplains

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Geologic Cycle

• The following all play major roles in the
  creation of natural hazards and are interrelated
• Tectonic cycle
• Rock cycle
• Hydrologic cycle
• Biogeochemical cycle

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Tectonic cycle

• Involves craton (solid core of continents)
  movement, and destruction of tectonic plates
• Large-scale processes deform Earths crust and
  produce various landforms
• Key to volcanic and earthquake activity

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Slice of Earths interior

• Denser material toward the center
• Crust is very thin relative to entire depth
  measurement
• Lithosphere is fairly rigid continental and
  oceanic crust on top
• Asthenosphere is hot and plastic

Fig 1.7b
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Fig. 1.8 Earths tectonic plates note
continental and oceanic plates divergent,
convergent and transform sliding boundaries
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Fig. 1.9 Interaction of plates Note
seafloor spreading boundary types broken
mid-ocean ridge subduction occurs Where
are the natural hazards here?
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Fig. 1.10 San Andreas fault zone What will the
result of this motion be in 20 million
years? Sacramento and San Joaquin Valleys
are most likely ocean floor
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Fig. 1.11 Hawaii hot spot and the result of
the Pacific Plates moving over it Whats at work
here?
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Fig. 1.12 Rock cycle Notice how all rocks are
connected in some way As a rule sedimentary
rocks are the most susceptible for producing
hazards, such as landslides and debris flows
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• Rocks consist of minerals
• Mineral
• A naturally occurring, inorganic crystalline
  solid having a limited chemical composition and a
  definite internal atomic structure
• Which of these are minerals?
• Gold, quartz, water, ice, iron, diamond

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Rocks in disasters mass wasting

• Layered rocks and minerals dont hold up well
• Clays and phyllosilicates
• Sedimentary rocks such as shale
• Certain metamorphic rocks, esp. slate
• Solid rock can move as a unit
• Rock slides of blocks of granite

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Hydrologic cycle

• Movement of water from oceans to atmosphere and
  back
• Driven by solar energy
• Various residence times

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Wheres the water?
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Impending events

• Various terms relate the possibility of an event
  occurring
• Probability of occurrence works for future,
  short-term floods but not always reliable
• Precursor events smaller events that portend a
  larger event
• Forecast has a stated certainly level
• Prediction stating when and where an event will
  occur (hurricane strike, flood)
• Warning heads up that the event will occur