ISNS 4359
EARTHQUAKES AND VOLCANOES
Spring 2005- (the last lecture)
Steve Bergman, Instructor
Lecture 25. Importance of Earthquakes and Volcanoes - Risk & Costs
Last 200 years Worldwide: Earthquakes killed ~6,000,000 people; Volcanoes ~300,000
Last Century: ~1200 Earthquakes killed >3,000,000 & caused >$1 trillion damages (Y2K values)
~200 Volcanic eruptions killed ~100,000 people & caused >$10 billion damages
~75% of earthquake casualties were due to building collapse.
Three Types of Tangible Loss Costs (measurable)
Physical loss-cost of repairing physical environment.
Economic loss-costs of physical loss, emergency operations and relief, & lost economic production.
Insured loss-costs paid by insurance companies.
Intangible Loss-Difficult to measure and value Human death, injury, misery, deprivation, effects on morale, confidence,
historical heritage, culture (all of which contribute to the quality of life and community identity).
Risk-likelihood of human or property loss resulting from a hazard
Public is willing to accept voluntary risks ~1000 times greater than involuntary risks.
Risk perception is controlled by exposure, familiarity, preventability, dread/horror; [do not be deceived]
Selected Odds for Dying from Various Causes (~1/200 people die per year in the USA)
Note these are rounded long-term averages and are highly variable, dependent on location, age, etc. (Morrison, 1992)
Smoking Cigarettes
Motor Vehicle Accident
Homicide
Fire
Airplane Crash (or EQ living in Iran)
Flood
Tornado
Earthquakes & Volcanoes
EQ living in CA
1/7
1/100
1/300
1/800
1/20,000
1/30,000
1/60,000
1/80,000
1/2,000,000
Top Ten Most Common Causes of Death in the USA
1. Heart Disease, 2. Cancers, 3. Cerebrovascular Diseases, 4. Pulmonary Diseases, 5. Accidents,
6. Pneumonia & Influenza, 7. Diabetes, 8. HIV (AIDS), 9. Suicide, 10. Homicide & Legal Intervention
Need more data? Check out http://www.nsc.org/lrs/statinfo/odds.htm for a comprehensive tabulation of detailed
“2001 odds of death due to injury” statistics from the National Safety Council.
World Population (UN medium growth) 2000- 6 billion (G), 2015- 7.2 G, 2030- 8.1 G, 2075- 10 G
At the turn of the century, 70% of the world’s super-cities (>2 million) are in seismic zones (MMI>VII),
20% are in severe seismic zones (MMI>VIII), 10% highly destructive intensities (>IX)
~30% of the world population lives on or near an active fault
~10% of the world population lives on or near an active volcano
Postscript: Impacts of Living on Unstable Land - Growing up with an abusive parent, Mother Nature
Humans have coped with unpredictable agents of geologic violence for as long as they have walked the earth.
Intelligent action can minimize loss when the planet shrugs its brittle skin or vents its excess pressure.
Two Alternatives: Adaptation or Extinction
The Energetic Earth : Gravity pulls/pushes/shears plates; Internal heat flows up; Solar energy controls climate.
Plate Tectonics (‘tekton’ Greek for ‘builder’): Subduction, Spreading, Strike-Slip (compression, extension, shear)
The Pacific Plate Margins: Ring of Fire…Ring of Fear? Locus of energetic Earthquakes & Volcanoes
Convecting Mantle with a twist: Hot Spots, Mantle Plumes, and Flood Basalts
Two views of inter-related natural processes that transform the face of the earth:
Slow (continuous, gradual)
versus
Catastrophic (sudden)
{Rain, wind, rivers, glaciers, plates}
{Volcanoes & Earthquakes}
Four Main Lessons Learned from Past Events:
1. Avoid living/building in dangerous spots;
3. Monitor to detect, predict & evacuate;
2. Build strongest possible structures;
4. Design refuges and evacuation drills.
33 years of natural disaster fatalities: (1947-1980) [total 1,226,000]: 210 hurricanes (500,000),
180 earthquakes (450,000), 333 floods (195,000), 18 volcano eruptions (9,500), 119 tornadoes (9,500),
7 tsunami (5,500), 45 landslide/avalanche (11,000), 147 other severe weather (47,000)
[source-Abbott (2002) Natural Disasters].
Annually/worldwide:
~100,000 felt earthquakes (M~>3.5);
~1,000 earthquakes strong enough to cause serious damage to property;
~30,000 earthquake fatalities (average of 20th century);
~50-100 volcanoes erupt on land;
~1,000 volcano fatalities (average of 20th century).
In addition to time-honored religious and magical means of protection, people living along active faults or in
volcanically hazardous areas can benefit from modern scientific techniques to minimize loss of life & property.
Volcanoes
Top Five most deadly volcanoes (total deaths of the last 4 centuries)
1815 Tambora [92,000], 1883 Krakatau [36,500], 1902 Mt. Pelee [29,000], 1792 Unzen [14,000], 1783 Laki [9,500]
4 easy steps to mitigation
Step 1. Define precise nature and degree of potential threat.
Step 2. Determine areas of highest risk (incorporate historical eruption data) & prepare Hazard Maps
(do not suggest/permit development in hazard zones).
Step 3. Monitor activity with advanced instruments (seismometers, tilt-meters, etc.).
Step 4. Evacuate when eruption is likely.
Earthquakes
Most deadly earthquake of the last 25 years: 26 Dec 2004 Great Sumatran Mw=9.2 Earthquake & Tsunamikilled over 300,000 near the coast along the northern Indian Ocean, but mostly in Indonesia.
China has experienced history’s worst natural disasters:
1556 Shaanxi earthquake: 830,000 deaths
1976 Tangshan M7.7: official report-240,000 deaths (outside observers estimate 500,000-800,000)
In regions where large earthquakes are infrequent, complacency allows substandard construction.
Some Factors affecting # deaths & damage: Magnitude, Intensity, Geology, Time of Day, and Architecture
4 easy steps to mitigation
Step 1. Determine areas of highest risk (incorporate historical earthquake data) & prepare Seismic
Hazard Maps incorporating soil & bedrock data (do not suggest/permit development in hazard zones).
Step 2. Retrofit existing structures, build seismically isolated buildings and specially engineered structures.
Step 3. Monitor activity with advanced instruments (seismometers, strain-meters, etc.).
Step 4. Evacuate/prepare when earthquake is likely.
Earthquake resistant buildings: lateral bracing (shear wall, diagonals), continuous tied-wall
foundations, tied facades.
Uncertain Risks (possibility that something bad is going to happen)
Overestimate risk- foolish fears; Underestimate risk- foolish unpreparedness.