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1
Natural DisastersIntroduction
Washington MudslideLa Habra Earthquake
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What is Geology?• Geology helps drive natural disasters• Geology is the study of the Earth and its history• Geology determined by plate tectonics
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Natural Processes• Natural Processes have been occurring since the
beginning of Earth’s History• Examples of Natural Processes (a process existing
in or produced by nature (rather than by the intent of human beings); "the action of natural forces"; "volcanic activity)
– Earthquakes– Volcanoes– Landslide– Tornadoes– Hurricanes– Floods– Fire– Meteorite impact– Heat wave– Drought– Cold wave
Fig. 1-5, p.6
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Benefits of Natural Processes
• Such processes are beneficial to humans because they are responsible for making the Earth habitable for life
VolcanoesResponsible for ocean and atmosphere
Earthquakesresponsible for mountain ranges which influence climate zones
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Natural Hazards
• “Natural processes” become “hazards” because people choose to live where they occur
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Natural Process vs. Natural Hazard
• Natural Process (left) San Andreas Fault in remote area of California – notice how streams are displaced• Natural Disaster (right) Oakland, California earthquake in 1989; Freeway collapse, 62 deaths
San Andreas Fault
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Natural Process vs. Natural Hazard
•Natural Process (left) Mount St. Helens, Washington eruption
•Natural Disaster (right) Mount Pelee in 1902 – 29,000 deaths
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Natural Process vs. Natural Hazard
•Natural Process (left) landslide in remote area•Natural Disaster (right) La Conchita, California in
2005; 10 deaths, 36 homes destroyed
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Natural Process vs. Natural Disaster
•Natural Process (left) Flooded floodplain•Natural Disaster (right) New Orleans, Louisiana, 2005; >1,900 deaths, $81 billion damage
Definitions
• Natural Hazard– Natural process posing threat to
properties/humans
• Natural Disaster– Natural process causing loss of
property/life
• Natural Catastrophe– Natural process causing significant loss
of property/life
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Why do we build in these areas?
•Beachfront home (Who wouldn’t want to live here?)
•Susceptible to beach erosion and landslides
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Why do we build in these areas?
•Forest home (view and serenity)
•Susceptible to forest fires
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Fractal—things looking the same regardless of size
• Magnitude (M) of an event is inversely proportional to the frequency (f) of the type of event
– Small avalanches are numerous
– Larger avalanches are fewer
– Giant avalanches occur rarely
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Predicting Hazards
• Poor odd of predictions
• Rely on forecasting– Based on
Recurrence Interval– Recurrence Interval
is probability that an event will occur within a certain period of time
• E.g. Large earthquake on San Andreas fault every 150 yrs.
• No major earthquake in over 250 years *(1680 7.7M) YIKES!
• Major flood every 50 years
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Risk
• A hazard considered on its recurrence interval and expected cost
• Hazard x recurrence interval x cost = risk• i.e. the greater the hazard and shorter recurrence
interval, the greater the risk
The 15 deadliest Natural Disasters in 1999
Fatalities
Date/start
Event Country
50,000 15 Dec Flood and Mudflows Venezuela
19,118 17 Aug Earthquake (Izmit) Turkey
15,000 29 Oct Hurricane India
3,400 20 Sep Earthquake Taiwan
1,300 3 Oct Floods and Landslides
Mexico
1,185 15 Jan Earthquake (Quindio)
Colombia
834 12 Nov Earthquake Turkey
751 20 May Hurricane Pakistan/India
725 16 June Floods (Yangtze River)
China
662 25 Oct Floods Vietnam
411 6 Aug Floods (West Bengal)
India
307 12 Jul Floods (Andhra Pradesh)
India
275 31 Dec. Cold Wave India
265 30 Jul Floods Philippines
224-----------------94,457 total
15 Jul Heat Wave in east U.S.A
Abbott, 2006
Human Fatalities
• Worst Disasters--Global:– Floods– Hurricanes– Earthquakes– Severe Weather– Tsunami ???
Major U.S. DeathsDisaster % Deaths
Heat/Drought 27.8
Flood 16.3
Winter Weather 14.9
Tornado 11.1
Lightning 10.8
Storm Surge/Coastal Erosion
9.6
Avalanche 4.6
Wildfire 2.8
Earthquake/Tsunami
1.9
Volcano 0.2
The Result of All Disasters
LossesHuman loss and Economic
Loss
• Increased Economic Losses—– More People (3-6 billion increased in 40 yrs)
• Potential impact of natural disaster relates to– size of event – location of event
• Few people or buildings little damage• Heavily populated area catastrophic deaths and
damage
Human Impact of Natural Disasters-Factors
• Why does the cost of natural hazards dramatically increase?– More people in path of catastrophic
events– Greater economic losses in
industrialized (developed) countries (Whereas Increasing numbers of deaths in underdeveloped (developing countries)
– Lack of regulations, and codes
People often move to hazardous zones
• For the views,• Because of cheap land, • Because of fertile land,• Proximity to recreational
opportunities• Jobs etc.
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Mitigation• Defined as efforts to prepare for disaster
and reduce damage• Mitigation Strategies
– Land Use—Limit development in dangerous areas
– Insurance—decrease financial impact– Government—Sponsor research, develop
policy and regulations related to natural hazards
– Public Education—Educate public about natural hazards
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Something to think about . . .
•Bay of St. Piere, Martinique (left) in 1902 after eruption of Mount Pelee in background
•Bay of St. Piere, Martinique (right) in 2005 with Mount Pelee in background
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Something else to think about . . .
•Weed, California (left) – sits at the base of Mount Shasta and is built on a debris avalanche
• Ancient Landslides (right) – 300,000 years ago a debris flow (brown) flowed 30 miles from volcano (arrow depicts direction of movement)
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One More Thing to Think About . . .
Reverse faults Strike-slip faults Blind faultsSCF:San Cayetano RF:Raymond EP:Elysian ParkSSF:Santa Susana SJF:San Jose LC:Las CienegasORF:Oak Ridge NIF:Newport-Inglewood SFS:Santa Fe SpringsSMaF:Sierra Madre PVF:Palos Verdes CH:Coyote HillsVF:Verdugo SAF:San Andreas LAB:Los Angeles BasinMCF:Malibu Coast WF:Whittier CLA:Compton-Los AlamitosSmoF:Santa Monica EF:ElsinoreHF:Hollywood CHF:Chino Hills
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