EESA05 - Environmental Hazards - Lec 1 (near-verbatim)

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Environmental Science
Mandy Meriano

EESA05 Lecture 1: PY Date: Sept 11, 2012 Why is it that were facing so many hazards? o Earth is working the way it should be (weve had earthquakes, tornadoes, volcanos etc; forever)...but why is it becoming more hazardous? Theres more ppl o Natural event is really not a hazard by itself; its only when we get in the way, it becomes hazard b/c therell b cost; life, property, economic downturn Well look at why certain areas are more susceptible to natural hazards? Look at: o Urbanization, popn density Earthquake hazards slide: o 6.4 9.3 magnitude o Sumatra earthquake = one of the biggest o 2011: tsunami in Japan Thru historical records, we know that weve had many earthquakes some large, some small but its not only the big ones that cause a lot of problem o Over 250,000 ppl killed from earthquakes causing tsunamis Cant predict when exactly earthquake will occur but maybe can put up efficient warning sys o So, how to mitigate Graph that shows years on x axis and dollar amount on y axis o Theres a cost associated w/ environmental hazards o Increased over time b/c theres more infrastructure and were becoming more developed, greater popn increase, more expensive everything o We like to live near water, mountains, volcanos (fertile land) We consciously pick areas more prone to hazards o Businesses not exactly at the region of environmental hazard will still be affected Slide 18: Are hazards random distribution or is there a reason for where they happen? o Theres something going on in those parts of the world where we see most of these hazards o The way the earth works actually makes certain areas more susceptible to geological hazards o Can we actually predict hazards? It would be good to be able to mitigate the negative effects of these natural hazards; save lives or infrastructure Once we understand how the system works, then we can maybe predict Certain hazards we can predict w/ more accuracy than others in terms of timing: tornados, hurricanes, meteorites (if big, can be monitored), tropical storms, floods, forest fires If really dry conditions for couple yrs, will know for sure there will be more forest fires Slide 19: 1 EESA05 Lecture 1: PY Date: Sept 11, 2012 Hazards = naturally occurring, but has effect on human interests which is why they become hazards ; otherwise, they would just be naturally occurring phenomenon Risk = Probability of event occurring multiplied by impact on people and property o Certain risks we take all the time b/c we know not much is going to happen; smaller risk Disaster Castastrophe = same thing as disaster but has much greater effect on human life/loss of infrastructure/economic loss Slide 20: Graph shows a hazard: the magnitude and the # of events associated with that magnitude X axis = log moment = quantifies how strong an earthquake is (how much NRG is put into causing that type of earthquake); as the magnitude of the earthquake gets bigger, the less frequent it is Log graph so relationship is exponential Larger events = lower frequency When it comes to predicting things, this type of graph is really impt; you have many smaller earthquakes than larger ones (etc; floods, etc;) Some of the worst disasters are relatively large events Slide 21: Effects of selected hazards in Canada and US: o See that the natural hazards that cause the greatest loss of life arent necessarily those that cause the most property damage o For ex: earthquakes = high catastrophe but around only 50 deaths/ yr o Landslide = low w/ 30 o Heat = more than 600 deaths/yr but in terms of the catastrophe potential, not really that high o Freezing rain = lot more ppl die from this even though only medium risk o Lot more ppl die from lightning than from floods o Major catastrophe may not be as bad as all the small things that could happen b/c small things happen more often Slide 22: Magnitude and Frequency of Hazardous Events Impact o Fxn of magnitude and frequency (ex: magnitude of earthquake, NRG associated w/ that event; more NRG in system, the bigger it will be) o Influenced by other factors (ex: climate, geology, vegetation, land-use, population) Magnitude-frequency concept- o Inverse relationship btn magnitude and frequency x M=Fe o the larger the magnitude, the smaller the frequency 2 EESA05 Lecture 1: PY Date: Sept 11, 2012 History of an area gives clues to potential hazards: o Maps, historical accounts, climate and weather data o Rock types, faults, folds, soil composition Slide 23: What makes ppl continue to live in areas with well-known hazards? We like to live near water People are fond of where they were, so they go back to the place even if there are hazards; culture, place you were go back and build it again New Orleans: hurricane ppl died, property lost AGAIN but ppl go back, b/c its their home Theres also a problem with forcing ppl out of certain areas o We know that ppl in New Orleans are at constant threat of hurricanes but nobody can force them out unless gvt has the rights to that at a certain time Scarborough bluffs erosion so gvt says to evacuate house otherwise itll just fall over The hazard may actually provide a benefit (ex: rich soils near volcanos/floodplains) Unknown liabilities if gvt forces ppl to move Increased popn pressure means more ppl are living in dangerous areas Slide 24: Often there is a lack of understanding of the geological history of an area The likelihood of rare hazards tends to be underestimated Hazards may be understated for political reasons (Scarborough bluffs - erosion); Pickering with major fault line and theres nuclear power plant (may think that fault line is no longer active and therefore its ok and then you find new info proving otherwise) Were still learning more about hazards, with better tools and technology o Better satellite pics Slide 25: Hazards and Public Policy In 1993, the EU proposed lowering the acceptable limit of cadmium in wheat imports The new levels would have excluded most CDN wheat High CD levels in wheat come from soil Glaciers advanced over CD-rich shales in Manitoba results in wheat in high cadmium levels = more than the limit proposed by EU would have been disastrous for those provinces where wheat = major economy Look at hazards, look at risks and then you evaluate them o What is an acceptable risk level that we can tolerate? Slide 26: o The way we build nuclear facilities: must be stable for at least 10,000 years and for as long as 100,000 yrs o Sometimes we have no choice, make decisions that put us in harm 3
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