Geo 2152 December Exam Reading Questions

In the laboratory, why are the scientists interested in learning about the density of the meteor? The Chelyabinsk meteor fragments were found to be 90% rock and 10% metal. What else did the microscope scans reveal about the meteor fragments?

- A weak low-density asteroid will also break up higher in the atmosphere and explode higher up higher up. A denser, stronger asteroid will make it deeper into the atmosphere and explode at lower altitudes. - Because it was 90% rock, it shows to be a much less dense asteroid. While denser asteroids might survive the journey, rocky asteroids like this one are much less resilient - So, in this case, the asteroid may have met its demise early in its entry. The microscope scans reveal that the meteorite fragments have significant internal cracks, weaknesses that would have contributed to the sudden, explosive breakup of the rock.

How do gophers help to encourage both more plant and animal life in the pumice plain? How do elk help to encourage more animal life in the same area?

- Gophers enrich the pumice by burrowing their way through the ash. They mix in fresh soil and help new plants to spread. - When you walked around the landscape, it was those islands created by gopher-turned soils that were very green and full of flower and seeds - The gophers also play another role in helping wildlife spread. they create kilometers of underground tunnel systems - When elk move across the landscape, they collapse the tunnels, creating entrance ways that salamanders and other amphibians can get access to. And once they get beneath the ground, these are very cool and moist sites that enable them to survive in an otherwise inhospitable area. And the importance of that is that it allows them to use these underground burrows as stepping stones during hot, dry weather and eventually to colonize new patches of terrestrial habitat, as well as ponds and lakes

In the past, the relationship between beetles and the forest was considered mutually beneficial. Explain how that has changed in recent years.

- Not all beetles attack trees. Generally, the few that do only attack the highly stressed or dead ones. However, more recently, in particular the mountain pine beetles will attack the healthy ones

Besides the construction of levees, what are two other ways humans have caused ground subsidence in the Mississippi River delta?

- Pumps and channels, as well as a Coastal restoration plan

How has the beetle indirectly impacted water resources for both people and salmon in waterways?

- Since warmer weather has allowed the beetles to expand, when they kill trees, it makes it difficult for salmon to survive. The trees are vital for salmon, as they slow snowmelt, and keep springs cool and limit excess silt

Describe the composition of a stony iron meteorite. How does this differentiate them from other meteorites in terms of weight?

- Stony iron meteorites are a mixture of rock and metal. Because they've got so much metal in them, they are much heavier than a normal rock from Earth

How did the bacteria in Spirit Lake make life impossible there? Why was the discovery of phytoplankton in the lake so important?

- The bacteria rapidly consumed the oxygen, making life impossible for any air-breathing organisms including fish, amphibians and insects - Phytoplankton are plants that turn sunlight into oxygen - They are the basic building block of aquatic life - As light level continues to grow, the plankton population grows - Bringing Spirit Lake back to life

What did the nuclear weapons monitoring system reveal about the explosion of the meteor?

- The computer simulation recreates the final moments of the meteor's trajectory through the atmosphere and shows the devastating blast wave - The simulation shows that, because the meteor was entering at a shallow angle, much of the energy of the blast wave was expended as it moved horizontally. The meteor was destructive, but it could have been far worse, if the blast wave had been focused more downward - If the meteor had struck at a sharper angle, plunging more directly towards the ground, what we see is something very different: allowed to explode at 23-and-a-half kilometers above the surface, but it continues to move downward at very high speed. The blast wave, when it gets to the ground and reflects, and then you see this shockwave moving across this surface. And that would have blown down trees and structures. If the area directly under this were populated, it would cause a lot of casualties. It would have caused a lot of destruction

How has the elimination of some forest fires contributed to the mountain pine beetle problem in British Columbia?

- The elimination of forest fires has allowed the mountain pine beetles to continue attacking trees at an even greater rate, as the trees cannot burn naturally anymore - The vulnerability intensified the epidemic of mountain pine beetles

Describe how female beetles have evolved to survive the natural defenses that the trees produce.

- The first defense the tree has, is when the beetle chews on the bark, the tree releases resin. Normally, the resin should kill the beetle, but they have evolved to be able to ingest it

What did the scientists do in order to monitor the volcano after they realized there was potential activity in its crater? What did they learn from doing this?

- The geologists set up instruments to monitor what's going on, including seismometers that can detect tremors set off by lava as it forces its way through the rocks. They place a series of these as close to the lava dome as possible. - A seismic record, like this, records any vibration of the ground, so we can see real rock- breaking earthquakes; we can see rock falls - The seismic record reveals a cyclical pattern - The pattern is so regular that when the cycle begins, the scientists can accurately predict what the volcano will do next. When the first rock-breaking earthquakes occur, they know it's only a matter of days or weeks before the lava starts to flow again

What is NASA planning to do in order to discover more asteroids in the future?

- The most efficient way to discover these near-Earth asteroids would be to have an infrared telescope in space, because these objects are dark and they radiate strongly in the infrared wavelengths - Known as Sentinel, the proposed instrument would take up a station in an orbit around the sun. Clear of atmosphere and packed with infrared sensors, it would allow us to detect asteroids far earlier and with greater accuracy

What plant were the scientists surprised to find in the pumice plain? How was it able to grow in such an inhospitable area?

- They were surprised to find a prairie lupine, a species that typically grows high in the slopes of Mount St Helens - It was able to grow from a special root structure that provides its own fertilizer - These are little factories, where bacterium works with the plant and provides nitrogen, to the plant. In return, the plant provides the bacterium with simple sugars, that it fixes through photosynthesis

Explain what is meant by tipping an ecosystem. Why are the beetles only partly to blame for such a phenomenon?

- Tipping an ecosystem refers to pushing a forest towards death by rising temperature - Beetles are only partly to blame as huge wildfires are also responsible for killing trees

What is the reason that some scientists believe that the beetle could potentially spread all the way to the Atlantic provinces of Canada?

- Warmer weather has boosted the beetles' population and greatly expanded their range—they're flourishing farther north and at higher elevations, invading pine trees

Describe the specific incident that occurred on April 20, 2010 which led to the explosion.

A large gas bubble infiltrated the casing and shot straight up causing an explosion

What is the proposed reason for the seismic activity on Baffin Island in Nunavut?

A Charlevoix seismic zone --> areas where seismic activity may be caused by the ground slowly rising thousands of years after the glaciers that once covered it melted, a movement known as post-glacial rebound

How does a core sample from the ocean floor reveal a past earthquake event?

Anomalous band of rock and chunks of wood debris that interrupt the core's muted brown tells a violent story

What was causing the small signals on the seismograph that the scientists called 'drumbeats'? Why did seismic activity on the mountain stop in 2007?

At the observatory, where geologists have been puzzling over the strange seismic traces, they now realize what they are: they're the unique autograph of the giant spines as they push their way out of the ground - This is the seismic signature of solid blocks of rock, grinding their way through the volcano, coming out onto the surface. As they do, they make these small, seismic signals, one just like the other, just like the other, very repetitive. We came to call them drumbeats - The drumbeats continue for several years. Spine after spine of solid lava emerges from the crater floor. It's unlike anything geologists have seen on Mount St. Helens - in 2007, as if to confirm this new insight, the familiar drumbeat seismic traces vanish completely. No more spines appear. The lava below the mountain has finally run out of gas

Shortly after the spill, what was deemed to be the most effective way of preventing oil on the surface of the water from reaching shore?

Burning the oil, a practice that was used with the Exxon Valdez spill

What were some of the early problems with the Deepwater Horizon well? Why was there such urgency within the BP oil company to drill faster?

Drill pipe got stuck in a borehole, as did a tool sent down to find the stuck section. By April 20th they were 6 weeks behind schedule and delays cost them more than $500,000

Why is the deep water in the Gulf of Mexico such a difficult location for drilling?

It is a difficult place to drill because the seafloor falls off the gently sloping continental shelf into a jumbled basin-and-range like terrain, with deep canyons, ocean ridges, and active mud volcanoes 500 feet high

With permission from the U.S. EPA, how did the BP oil company attempt to reduce the oil spilling directly from the well?

Pump hundreds of thousands of gallons of dispersant directly into the oil and gas spewing from the well, a mile beneath the surface, helping create deep water plumes

Why was the Christchurch earthquake of 2011 a surprise to scientists?

Scientists didn't even know there was a fault in the region until a much less damaging 7.1 earthquake occurred in September 2010

Describe the story behind the real Smokey the Bear. What is Smokey's objective?

Smokey was an actual cub who was orphaned by a fire in New Mexico Smokey's objective was to promote fire prevention

What were several factors that led to the giant wildfire of 1910?

That spring, little rain fell. By summer the Northern Rockies were tinder dry. Locomotives scattered sparks along tracks, starting fires that spread into the forest. Summer thunderstorms brought lightning. The fires began to multiply. Then on August 20th a cold front moves through and essentially combines small fires to merge into a huge firestorm

What evidence exists today to prove that Dodge's escape fire at Mann Gulch worked? What modern technology was used to explain the peculiar behaviour of the escape fire?

The fact that that escape fire worked for him also saved these trees that are up here in the ridgeline. These are trees that were here in 1949 that owe their existence to the fact that Dodge's fire burned out the fuel around them, and when the main fire came up the hillside it swept around his fire and these trees and they survived the fire. It took modern computer modeling to unravel this mystery. As heat from the main fire rose, the updraft sucked cooler air into its base, creating a wind in the opposite direction. With the opposing winds neutralizing each other, Dodge's fire simply followed the contour of the hill, leading Sallee and Rumsey up to salvation.

Based on the window forecasted by the scientists at the Sidney laboratory, in what time range will the next strong earthquake occur in the region? (Provide the range by giving the specific years).

The last 1700 quake was 315 years ago, a number that's five years away from being within Randy Enkin's window of megathrust reoccurrence (written in 2015). Can occur between 200-800 years apart

Considering the massive explosion and shockwave, why wasn't the damage in Chelyabinsk worse?

The simulation shows that, because the meteor was entering at a shallow angle, much of the energy of the blast wave was expended as it moved horizontally. The meteor was destructive, but it could have been far worse, if the blast wave had been focused more downward.

What is currently occurring on Vancouver Island that provides a clue to a potential future earthquake there?

The surface of the island is currently bulging up two millimetres per year on its western edge informs models of where the North American plate and Juan de Fuca plate are locked and storing the greatest amount of energy

Describe what occurs in the lead-up to a megathrust earthquake.

The tectonic plates move toward one another continually, but can get stuck when in contact, creating over long periods of time an immense build-up of strain that eventually exceeds the friction between them; when that point is reached, an earthquake occurs

How do ponderosa pine forests give clues to past wildfires? Describe the appearance of ponderosa pine forests.

The trees themselves record the history of how forests burn. Embedded in their growth rings are fire scars, charred lines left behind every time the tree is scorched They were landscape-wide. They would spread across very large portions of landscape. Some years the whole Southwest was burning, we know from these fire scar records After the all the burns they thinned out the smaller ponderosas, leaving nutrients and space for others to grow big and tall. Fire created open, park-like forests quite unlike the ones we're used to today

How have the indigenous people on the west coast of the island been preparing for a potential tsunami?

They built their Big House up on the hill across the river and are in the process of building a subdivision there. The community's daycare centre often runs drills with the kids, who get 15 minutes to race to high ground

At what depth is an oil well considered to be deep water? How much of the world's oil will likely originate from deepwater wells in 2020?

Wells 1,000 to 4,999 feet below the surface & 10% in 2020

What are the beneficial applications of the motion sensors that Oceans Network Canada is currently prototyping on Vancouver Island?

Will allow for rapid detection and reporting of spreading seismic waves before they reach Vancouver and Victoria --> airports could stop planes from taking off or landing; gas companies could turn off the supply at the flick of a switch; and bridge entrance lights could turn red. The concept is to prevent secondary impacts of the earthquake

What is a blow-up?

where the fire leaps suddenly from the ground up into the canopy of trees. It's now a crown fire, the most extreme form of fire behavior