Natural Disasters zJohn Gyakum (AOS) zJohn Stix (EPS)

What are we talking about ? zDISASTER: zdis - unfavourable zastro - stars zTo the ancients, disasters were precipitated by the stars

Our role as scientists zIn a sense, the essence of science is to be able to PREDICT natural phenomena, to REDUCE their effects

Katrina, Monday 29 August 2005, 0715 hours Zulu time

Courtesy Washington Post

Katrina reaches Montreal

Some destructive natural events zEarthquakes: local to regional zFloods: local to regional zHurricanes: regional zTsunamis: regional to global zMeteorite impacts: regional to global

Relative energies of selected phenomena zComparing energies and equivalent magnitudes for natural phenomena (from Brumbaugh, 1999)

Some important definitions zHazard: potential threat to humans and their welfare zRisk: probability of loss (deaths, injuries, damage, disruption of economic activity) as a result of a particular natural event zVulnerability: potential loss, or degree of loss, from the event (e.g., 0=no damage, 1=total loss)

Definitions (ctd.) zDisaster: a hazardous event affecting a community in an adverse way such that essential social structures and functions are disrupted

Definitions (ctd.) zPrediction and forecasting: statement that a particular natural hazard will occur with a given probability during a certain time frame in a specified geographic area zMitigation: efforts to reduce or minimize the effects of natural hazards on a community

Risk of death 1 zVolcanic eruption:1 in 30,000 2 zAsteroid impact:1 in 20,000 2 zEarthquake:1 in 200,000 3 zLightning:1 in 130,000 3 zTornado:1 in 50,000 3 zHurricane:1 in 25,000 3 zAirplane crash:1 in 20,000 3 zAuto accident:1 in z 1 to an individual over a 50-year period z 2 worldwide z 3 USA only

A question for all of us zWhy do people live where they do ?

People’s reactions to crises and disasters zAnger at scientists, officials, etc. zFrustration, especially if event is long- lived zSkepticism, which can be fostered by the media zDenial zSuspicion…a “plot” zRefusal to evacuate; people feel safest in their familiar surroundings

Prediction of natural phenomena zWhere are we ? zLong-lived vs. short-lived events zPredictable (hurricanes) vs. unpredictable (earthquakes) events zProblem of human time vs. geologic time zProbabilities of scientists vs. exact date and time of ordinary people

Scientific understanding of natural phenomena zOccam’s Razor: when several conflicting hypotheses or explanations are proposed for the same set of observations, the best explanation is that with the fewest independent assumptions

Causes and effects zA cause-and-effect relationship - and associated predictions - is an inherently deterministic view zIt works only with events whose outcomes occur with nearly 100% probability, e.g., flooding as a result of tidal forces

Unpredictability zMother Nature is non-deterministic zIndividual events are inherently unpredictable zThis requires a statistical approach such as probabilities, since we don’t fully understand many natural processes

Recurrence intervals and probabilities zRecurrence interval: average time interval between the occurrence of two events of given magnitude zAn example is a flood of 6 meters which happens once every 50 years, on average zOr an earthquake of magnitude 5 which happens once every 10 years, on average

Recurrence intervals and probabilities zThe flood: there is a 1 in 50 chance that such a flood will occur in any one year… zthis corresponds to a 2% probability of occurrence z The earthquake: there is a 1 in 10 chance that such a quake will occur in any one year… z and thus a 10% probability of occurrence

An example of non-determinism zA flooded city from a swollen river… z…is the flood the source of devastation, or the dikes built to modify the course of the river?

Another example of non- determinism zCasualties and destruction from a volcanic debris flow… z…did the flow cause the disaster, or the siting of the town on debris flow deposits of older eruptions ?

Meteorite impacts

The Cretaceous-Tertiary (K-T) extinction at 65 Ma zEnd of the dinosaurs and other species zIn fact, about two-thirds of all species wiped out z80% of all individuals killed off zThereafter, mammals took over

Tsunamis The Great Wave off the Coast of Kanagawa, by Hokusai, a famous late eighteenth- and early nineteenth-century Japanese artist.

4 case histories Alaska 1964 (earthquake-generated) Krakatau 1883 (caldera-generated) Unzen 1792 (landslide-generated) Grand Banks 1929 (submarine landslide- generated)

Volcanoes and volcanism zVolcanoes represent venting of the Earth’s interior zMolten magma rises within the Earth and is erupted either quietly (lavas) or violently (pyroclastics) Sakurajima Volcano, Japan Cinders were issued up to >2,500 m high 18 May 1991

Volcanic activity: pyroclastic flows zPyroclastic flows are suspensions of hot pyroclastic material, air, and gas which descend under the influence of gravity zTheir velocity is generally very high ( km/hr) zThis example is a flow from Mt. St. Helens

Avalanches

Avalanches were first imagined as giant snowballs which increased in size from accretion of underlying snow

Fully-developed powder avalanche due to cascading down near-vertical cliffs

Hurricanes

Hurricanes (continued)

Tornadoes

Floods New Orleans; August 2005

El Niño

Ice Storms

Web sites and readings zDefinition of terms used in this course: zhttp://pdm.medecine.wisc.edu/vocab.htm zUseful general web sites: zhttp:// (clearinghouse of disaster-related information) zhttp:// (links to useful disaster-related sites) zhttp://earthobservatory.nasa.gov/NaturalHazards/ (current events) zhttp:// (topics on disasters) (Natural hazard map of Canada) zhttp:// (an interactive tool to make hazard maps for the USA) zhttp:// (interactive hazard maps of the Pacific Ocean basin) zhttp:// (information on various natural hazards) zhttp://visibleearth.nasa.gov (images of various natural phenomena) zhttp:// (images of various natural phenomena)