Week 9: Technological hazards + meteors

Technological hazards

These have a wide and varied interpretation.

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They can vary from a single toxic chemical accident to an entire industry (e.g., nuclear energy).

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other examples may include exposure to pollutants or hazardous waste

Examples of technological hazards

Hybrid disasters may fit into this category.

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**Ex:**

* An earthquake that causes an oil or chemical spill from a pipeline

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Technological disasters involving the environment are included in this category as well.

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**Ex:**

* the sinking of the titanic and explosion of the challenger space shuttle

Vulnerability to technological hazards

Typically, the death tolls from technological hazards are relatively low.

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Vulnerability is greatest for those involved in industry or transportation systems.

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Workers in resource industries in hinterlands are at higher risk

(eg. miners)

Categories

__Widespread__

* long term (nuclear accidents)
* hazards leading to cumulative effects

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__Rare Events__

* airplane crashes
* mine collapses
* shipwrecks

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__Relatively Common__

* automobile accidents
* poisons

Cumulative effects

These are conditions that worsen slowly over time as exposure to a concentration increases.

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Eventually, the concentration reaches a threshold critical to human health.

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Hazards with cumulative effects include exposure to radiation, toxic chemicals, acid precipitation, and groundwater contamination

Calculating risk

Large-Scale Structures (buildings, bridges, dams):

Risk is defined as the probability of failure during the lifetime of the structure.

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__**Transportation (road, sea, rail):**__

* risk is the probability of death or injury per km travelled

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__**Industry (manufacturing, power production):**__

* risk is the probability of death or injury per person per number of hours exposed

Radon

The primary source of radon gas is from the natural decay of uranium in rock and soil.

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When radon is inhaled it then decays to polonium and lodges in the lungs where it damages tissues.

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It is the 2nd leading cause of lung cancer in North America

When does Radon become a hazard

when it is released into our living space.

* it is difficult to detect because the gas is odorless, colourless, and tasteless

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Radon detectors are commercially available in areas where it is of greater concern.

Potentially high radon levels are present in ___% of homes in North America

5-10%

How Radon moves

The gas can move quickly through non-saturated soil and can seep into homes.

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Basements are at higher risk especially in winter due to reduced air concentration

Genetically modified organisms

These are organisms that have had changes made to their DNA by the transfer of genes.

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Examples of feats in genetic engineering:

* chickens that lay low-cholesterol eggs
* tomatoes that can reduce the risk of cancer
* bananas and potatoes to treat some viral disease that are common in developing countries
* rice that contains vitamin A
* bacteria that can clean up oil and toxic spills

Genetically modified food

The most common crops that are genetically modified are corn, soybeans, and canola.

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Crops are modified to **increase yields.**

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Some crops have been genetically engineered to have greater resistance to:

* extreme changes in temp or precipitation
* herbicides
* pests
* acidic soil

Bioengineers have been able to alter citrus trees (that would normally take __**six years**__ to produce fruit) to yield fruit in only

____________.

one year

How safe are genetically modified foods?

Scientists believe that the benefits outweigh the potential risks but most support more research studies.

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UN food and agriculture organization believes that genetically modified crops have great benefits especially in developing countries.

Radiation

The pathways of radiation include inhalation and, ingestion (food, water).

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The impact can be __**direct**__ (effects are evident within days of exposure) or delayed and chronic (leukemia, cancer).

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The impact could also be __**indirect**__ in the form of genteic effects

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A person may not experience effects but may pass them on to their children in the form of chromosomal changes or birth defects.

Sources of radiation

__**Mining of Uranium**__

* In Canada, uranium is mined in northern Saskatchewan and northern Ontario.

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__**Production of Electricity**__

* uranium is used in nuclear power plants

mines produce wastes known as _____ that can be a radioactive hazard

tailings

Nuclear power plants

Most nuclear plants in North America are in the __**eastern half**__ of the continent. (where most of the population is)

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They must be near sources of coolant (rivers or lakes)

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They must be located near a market for electricity (eastern North America is much more populated).

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Nuclear is considered a clean source of energy because it does not emit the greenhouse gases that cause climate change

locations of nuclear power plants

Nuclear accidents

A *nuclear* *meltdown* is an informal term for an accident that results in damage from overheating.

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It occurs when the heat generated by a nuclear plant exceeds the heat removed by cooling systems.

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In a meltdown, fuel rods turn to liquid and the walls of the plant core could melt from extreme heat.

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The hot liquid could melt through the bottom of the plant and seep through the soil

Three mile island nuclear accident

This is the __**worst nuclear disaster in US history**__; it occured on March 28th, 1979.

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One of the two power plants on Three Mile Island in central Pennsylvania experienced a partial meltdown.

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It was caused by a failure of a valve that controlled cool water entering the plant core.

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There were no direct injuries; minor amounts of radiation were released around the site.

Chernobyl Nuclear accident

This is the __**worst nuclear disaster in world history**__; it occurred on April 26, 1986.

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The accident was a result of a flawed design, operator error, and disregard of safety regulations.

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An explosion at the plant caused the immediate deaths of 3 workers.  Within one year, 28 more workers died from extreme radiation exposure.

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An estimated 6000 people in the area developed thyroid cancer because of radiation poisoning.

Nuclear energy

The combined concern over Three Mile Island and Chernobyl slowed nuclear development for a time.

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However, concern over greenhouse gas emissions has created a greater demand for cleaner sources of energy.

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for example, Ontario has recently closed all its coal power plants🙏😍

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The province has invested in refurbishing existing nuclear power plants and is planning to build new ones as well.

Titanic shipwreck

The *Titanic* was a passenger ocean liner that struck an iceberg and sank on its maiden voyage (April 15, 1912).

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The ship left Southampton, England on april 10th and was bound for new york city with 2224 passengers

the titanic

The ship was designed using advanced technology and was believed to be unsinkable.

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The death toll ws 1517; the high number was due to the lack of lifeboats for all passengers

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The wreckage was found by SONAR in 1985 at a depth of 3.8km

Chronology of the the titanic shipwreck

A lookout on the ship spotted an iceberg in the ship’s path at 11:40 PM and alerted the captain.

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The ship struck the iceberg 37 seconds later; 18 lifeboats were launched, and *Titanic* sank at 2:20 AM.

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The Carpatha arrived at 4:10am and picked up survivors from the lifeboats

Oil spills

Oil spills most commonly occur in marine areas but can also occur on land due to pipeline bursts.

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The environmental impact can be devastating, and clean-up can take months to years.

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Oil penetrates bird feathers and mammal fur reducing their ability to insulate

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Animals and birds are left vulnerable to temperature changes and become less buoyant in water

Exxon Valdez oil spill

This spill was caused by an oil tanker striking a rocky reef off the south coast of Alaska on March 24, 1989.

* the region is an important habitat for salmon, seals, sea otters, killer whales and seabirds

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There were 75 million litres of oil spilled; the remote location made recovery efforts difficult.

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It remained the worst oil spill in north american history until the deepwater horizon oil spill.

Deepwater horizon oil spill

The spill was caused by an oil rig that exploded in the Gulf of Mexico on April 20, 2010.

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The explosion killed 11 workers. It was caused by methane rising upward through a drill pipe.

Approximately __ million liters of oil escaped from the well every day for months

11 million

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\*After several failed attempts, the well was finally capped with cement on september 19th 2010

repercussions of the spill

The spill caused extensive damage to wetlands and beaches along the U. S. Gulf of Mexico coastline.

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* The tourism industry faced severe economic loss during  Summer 2010.

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The U.S. federal investigative report ultimately blamed the B.P. oil company for the disaster.  The report found that the company:

* made a series of cist-cutting choices on maintenance
* did not have a proper system in place to ensure safety

Groundwater

Groundwater is water that is found underground within the cracks and spaces in soil, sand, and rock.

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These materials are permeable because they have connected spaces that allow water to flow through

Groundwater contamination

Many cities and towns obtain drinking water from groundwater.  If the water supply becomes contaminated, this presents a risk.

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In 2000, water contaminated with *E. coli* bacteria killed 7 people in Walkerton, Ontario.

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The baceteria came from fertilizer manure that had leached into a well during a heavy rainfall

Infrastructure failure

An example of infrastructure failure in North America occurred in Minneapolis in 2007.

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A highway bridge over the Mississippi River collapsed during evening rush hour killing 13 people.

Minneapolis bridge collapse

The cause was deemed to be excessive weight from vehicles and construction equipment

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The bridge supports were not of proper thickness and an extra 2 inches of concrete that was added to the roadway also contributed to the collapse.

Tacoma narrows bridge collapse

In 1940, high winds caused the collapse of a suspension bridge in Tacoma, Washington.

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There were no human casualties from the collapse

The bridge design

The design of the bridge did not provide any open trusses for wind to pass through.

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The incident has served as a good case study for engineering and architecture for students

Space shuttle accidents

There have been two major space shuttle disasters: the shuttles *Challenger* and *Columbia*.

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The challenger exploded 73 seconds into its flight on Jan. 28, 1986

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All 7 crew members were killed as the space shuttle disintegrated; its remains were scattered over the Atlantic Ocean.

The challenger shuttle

The cause was found to be a faulty O-ring seal.

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It is believed the cold weather lowered the resiliency of the rubber O-ring.

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* It failed to seal a joint leading to the release of hot gas that led to failure of the rocket booster

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The night before the launch was particularly cold; frost and ice had developed on the rocket.

The columbia Shuttle

The *Columbia* disintegrated on Feb. 1, 2003, upon re-entry into Earth’s atmosphere after 16 days in space.

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During launch, a piece of insulation broke off from the external tank

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It struck the left wing and damaged the system that protects the wing from the intense heat produced by atmospheric gases upon re-entry.

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Pieces of the shuttle were found in Texas and Louisiana

Formation of the solar system

How was the solar system formed?

Scientists believe a cloud of gas and dust in space was disturbed by a *supernova.*

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**When did this occur?**

* 4.6 billion years ago

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^^The Nebular Hypothesis^^

* the explosion of waves in space

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This caused formation of a ^^solar nebula^^

(flattened disc)

Supernova

The explosion of a star that has reached the end of its life cycle

formation of planets

The centre of the solar nebula grew hotter resulting in the formation of the Sun.

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The outer edges cooled causing clumps of particles to stick together and form planets

galaxy + star definitions

**Galaxy**

* a cluster of billions of stars. Our solar system makes up a tiny portion of the milky way galaxy

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**Star**

* A hot glowing ball of gas that generates energy by converting hydrogen to helium

The Sun is located approximately __**_______**__ from the centre of the Milky Way galaxy.

**30 quintillion km**

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It takes ______ years to travel from one side of the galaxy to the other

100,000 years

The sun

In the core of the Sun, the temperature is ==15,000,000°C.==

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The outermost part of the Sun is called the __**photosphere**__ and it is ==6000°C.==

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Energy from the sun controls the earth’s climate system

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The earth only receives one two-billionths of the sun’s total energy!

The solar system

The solar system is composed of 8 planets, 60 moons, and millions of *bolides*.

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__**Order of the planets:**__

* Mercury
* Venus
* Earth
* Mars
* Jupiter
* Saturn
* Uranus
* Neptune

Life cycle of stars

The Sun is the closest star to Earth; it has a life expectancy of 10 billion years.

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At the end of the life cycle of a star, massive amounts of energy are released into the solar system.

Bolides - definition

__**Definition:**__

* any extraterrestrial body that originates in outer space

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Bolide examples

==Asteroid:==

* A rocky metallic material in space 10 m to 1000 km in diameter originating in the Asteroid Belt (between Mars and Jupiter).

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==Meteoroid:==

* Similar to an asteroid, but only up to 10m in diameter
* so just a smaller asteroid

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==Meteor:==

* A meteoroid that has entered Earth’s atmosphere.

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==Meteorite:==

* a meteor that strikes earths surface

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==Comet:==

* these are distinguishable by a glowing tail of gas and dust
* It is believed that comets formed in an area outside the solar system called the Kuiper Belt.

Comets

Comets are composed of a rocky core of gas and ice.

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They create light as gases are released as the comet is heated by solar radiation.

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Halley’s comet is the most famous because it is visible with the naked eye and passes close to earth every 75 years

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it will next be visible in __**2061**__

Airbursts

Bolides travel at velocities of __**12-72 km/s.**__

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As they heat up upon earth entering earth’s atmosphere, they produce bright light

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The object may explode in an *airburst* at an altitude between 12 km and 50 km, or it will collide with Earth’s surface.

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Tunguska Airburst

The explosion destroyed over 2000 km2 of forest in a sparsely populated area of northeast Russia in 1908.

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Scientists have determined it was an airburst because no crater has ever been found

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The asteroid responsible is believed to be 25 to 50 metres in diameter.

Chelyabinsk airburst

On Feb. 15, 2013, a meteor exploded over the city of Chelyabinsk in southwest Russia.

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It was the largest bolide to enter earth’s atmosphere since the tunguska airburst

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Over 1500 people were injured, mainly from broken glass.

Impact cratoers

These provide evidence of past meteorite impacts.

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A layer of debris called an %%*ejecta blanket*%% consists of rock fragments that were blown out of the crater on impact.

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Craters today are not as deep as the original impact crater due to erosion and fragmented rock falling back into it shortly after

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* This rock is referred to as %%*breccia*.%%

Meteor crater

This crater is in Arizona and was formed about 50,000 years ago.

Impact craters

Impact craters can be defined as either simple or complex.

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Simple craters are less than a few km in diameter and do not have an uplifted centre.

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A complex crater consists of a rim that collapses under extreme faulting and a centre floor that rises following impact.

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Complex craters are generally greater than 6km in diameter

Manicouagan crater

This complex impact crater is 100 km in diameter and is one of the 5 largest in the world.

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It is in central Quebec and was formed approximately 214 million years ago

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Faulting caused the rim to collapse, and the rock has eroded to form a ring-shaped lake.

Chesapeake crater

This is a crater that was not discovered until subsurface imaging and drilling revealed its presence.

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The crater formed 35.5 million years ago.

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Since then, it has been overlain by sediment and seawater as sea levels have risen.

**Why are craters much more common on the Moon than on Earth?**

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* most impacts with Earth are over oceans where craters are not produced
* impacts with Earth’s land have been eroded or buried and thus have more subtle features than Moon craters
* smaller bolides often burn up and disintegrate in earth’s atmosphere before striking its surface

Shoemaker-levy comet

This comet entered Jupiter’s atmosphere in 1994.

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Massive amounts of energy were released, and gas plumes were produced as 21 fragments of the comet collided with Jupiter.

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After this impact, it was universally accepted that a similar impact could one day strike earth

Mass extinctions

Extinctions coincide with boundaries of geologic periods on the geologic time scale.

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These are usually consistent with abrupt changes in climate from plate tectonics, volcanism, bolides, or human impacts.

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There have been 5 major extinctions during the past 550 million years and a 6th is occurring today (climate change)

K-T boundary mass extinction (cretaceous - tertiary)

It occurred 65 million years ago from the abrupt cooling caused by an asteroid impact.

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It is named for the boundary separating the Cretaceous and Tertiary Periods.  In some languages, Cretaceous is spelled with a “K”.

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This event caused extinction of the dinosaurs which had been at the top of the food chain for 100 million years.

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It caused the extinction of 70% of all plant and animal species that existed at the time.

K-T boundary mass extinction cont.

How did we discover there was an impact?

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Scientists found large amounts of iridium in rock that was dated at 65 millions old.

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^^Iridium^^ is a rare element on earth, but is found in bolides.

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The hypothesis of an impact was at first criticized because no crater had been found.

K-T Boundary Crater

The K-T crater was discovered in 1991; it is 180 km in diameter and was found underlying sediment and seawater.

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It is located on the yucatan peninsula in mexico and was given the name ==Chicxulub crater==

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Analysis of the crater suggests the impact produced 10,000 times the energy of the entire nuclear arsenal of the world today.

Linkages with other Hazards

Bolide impacts can trigger tsunamis, earthquakes, landslides, and cause climate change.

Earth history

Risk from Bolide Impacts

If an asteroid remains in the asteroid belt (between Mars and Jupiter), it poses no hazard to Earth.

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The orbital path of an asteroid could be disturbed by a collision with another object

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It is estimated that there are about 1100 asteroids larger than 1km in diameter with near-earth orbits.

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Scientists estimate that an urban area would be destroyed once every 30,000 years by an asteroid similar in size to the Tunguska airburst (which has a 1000-year recurrence interval).

bolide impact frequency

Managing the bolide impact hazard

The Spaceguard survey program has catalogued all near-Earth orbits larger than 1 km in diameter.

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Extending the inventory to bolides as small as 100 metres in diameter is a current objective.

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If a large bolide is determined to be approaching

Managing the bolide impact hazard cont.

Blowing up an approaching bolide will cause fragments to rain down and is not advisable.

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Pushing a bolide off course by ramming it with a spacecraft is the recommended approach.

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This was tested for the first time in september 2022 when a spacecraft impacted the asteroid dimorphous 11 million km from earth