Natrual disasters

What types of natural disasters killed most people in the past 40 years?

Tropical storms (hurricanes) and earthquakes

Where in the world are deaths from natural disasters the highest?

China

Where in the world are insurance losses from natural disasters the highest?

Asia

What is a great natural disaster?

A disaster so overwhelming that outside assistance is needed to handle the rescue for the region

What is the difference between a natural disaster and a natural hazard?

Natural hazards are inevitable, but natural disasters are not

For nations, what is the relationship between natural disaster, deaths, gross domestic product, and level of democracy?

There are less deaths with nations that have a democratic government and higher national income.

What is the relationship between the magnitude of a given disaster and its frequency of occurrence?

The smaller the earthquake the more often you get them

Draw a curve showing the world population of humans in the past 100,000 years. Why has the curve changed shape so dramatically?

Population skyrocketed because humans have continued to improve their ability to modify the environment with better shelter and more reliable food and water supplies.

Explain the concept of exponential growth.

growth whose rate becomes more rapid in proportion to the growing total number or size.

For nations, what are demographic transitions?

Model that describes population (birth and death rates) change over time.

Natural Hazard

A source of danger to life, property, and the environment. The probability that a dangerous event will occur.

Mitigation

Actions taken by humans to minimize the possible effects of a natural hazard.

Describe how Earth became segregated into layers of differing density

INCREASING HEAT

1. Impact energy

2. Decay of radioactive isotopes

3. Gravitational energy.

How did Earth's continents, oceans, and atmosphere form?

Earth grew from random collision's of debris that formed homogeneous mixture of materials. The low density materials rose and accumulated on Earth's exterior to create continents, oceans and atmosphere.

Isostasy

The equilibrium in the earth's crust that floats upward or downward as loads are removed or added.

Describe some examples of isostasy

Add a load onto a boat, it sinks downward; remove the load and the boat rises upward. Add a load of land onto a continent, and the land will sink downward. Remove the load, and the land rises upward as rock flows inward.

What energy sources caused the interior of the early Earth to heat up?

Impact energy, gravitational energy, and ongoing decay of radioactive isotopes.

How does nuclear fusion differ from nuclear fission?

Fission is splitting of a large atom into two or more smaller ones, fusion is the fusing of tow or more lighter atoms into a larger one.

What is the age of Earth? How is it determined?

4.57 billion years old. Measured using radioactive isotopes and their decay products collected from moon rocks and meteorites.

Where are the oldest known Earth rocks found? How old are they?

Northwest Canada, 4.055 billion years old

What are the differences between brittle, ductile, and elastic behavior?

Brittle: stress causes abrupt fracture Ductile: stress causes permanent flow or strain, Elastic Behavior: stress causes deformation that is recoverable.

Explain some other evidence indicating that seafloors spread

Matching fossils and sedimentary rock on opposite sides of Atlantic. Presence of mid- oceanic ridges, area where new oceanic crust is created. Dating of rock on the ocean floor

What is a tectonic plate?

Deformation and movement within the earths outer layers

Explain the several lines of evidence indicating that the continents move about Earth

Plate tectonics, seafloor spreading, seismic observations

Describe a deep ocean trench. How does one form?

A portion of the earth's crust which is a tectonic plate being subducted below another plate. They form when the oceanic crust goes under the Continental crust. The oceanic crust then forms the trenches through a process called subduction.

How is earth's magnetic field formed? Describe the reversals of magnetic polarity from north to south?

Formed by the motion of molten iron alloys in the earth's outer core. Magnetic polarity from N to S represents the process that leads to a 180° reorientation of the magnetization vector with respect to its initial direction, from one stable orientation to the opposite one.

Explain the concept of uniformitarianism.

The concept that the same laws and processes operating on and within Earth throughout geologic time are the same laws and processes operating today.

Draw a map of an idealized tectonic plate and explain the earthquake hazards along each type of plate edge:

FIO

Sketch a map of the Arabian plate and explain the origin of the Iranian Holy Land, and Turkey earthquakes:

FIO

The Dead Sea fault zone is an Eastern Hemisphere analogue of the San Andreas fault in California. It runs right through the Holy Land and is responsible for much of the area's well-known topology. Pull-apart basins have formed by way of fault movements on both sides of the fault zone, filling up with water (Dead Sea and Sea of Galilee).

The Turkey earthquakes derive from the country being squeezed westward by the North Anatolian fault in the north and the Anatolian fault in the southeast.

Explain why earthquakes at subduction zones are many times more powerful than spreading-center earthquakes:

- Earthquakes at subduction zones are many times more powerful than spreading-center earthquakes because at subduction zones, 70-100km thick plates are being pushed back into the mantle, involving an immense amount of energy;

- Spreading center EQs simply cause rocks to fail in tension, which are relatively easy to rupture and often happen at high temperatures, making them fail even easier (less energy needed)

Explain the seismic-gap method of forecasting earthquakes:

Researchers have concluded that if segments of one fault have moved recently, then it seems reasonable to expect that the unmoved portions will move next and thus fill the gaps. However, one segment of a fault can move two or more times before an adjoining segment moves once.

Which tectonic plate edges fail most commonly in shear? In tension? In compression?:

The divergent or pull-apart motion at spreading centers causes rocks to fail in tension.

- I.e. pacific plate created by spreading centers along eastern and southern edges

The slide-past motion occurs as rigid plates shear and move around the curved Earth; plates shear and slide past each other in the dominantly horizontal movements of transform faults.

- Queen Charlotte fault located in northeastern pacific near Canada

- San Andreas fault in California

- Southwestern edge of Pacific ocean where the alpine fault cuts across the South Island of NZ

The convergent or push-together motions at subduction zones and in continent-continent collisions cause rocks to fail in compression.

- Pacific plate subducts along northern and western edges, resulting in massive EQs such as:

\-- 2011 Japana

\-- 1964 Alaska

\-- 1931 Napier in NZ

Why are fires in cities so commonly associated with major earthquakes?:

Earthquakes are associated with fires largely because they break gas pipes and bring down electrical lines. In less developed countries, they can also cause fires by upsetting things like kerosene lanterns or cooking fires. In modernized countries, fires come from broken gas mains and/or downed power lines. Broken gas mains leak gas out into the atmosphere where it can be ignited. Downed power lines cause arcing and sparks that can ignite gas and other flammables.

Sketch a plate tectonic map along western North America from Alaska through Mexico. Label the spreading centers, subduction zones, and transform faults. Label the maximum earthquakes expected along the coastal zones:

FIO

If seafloor spreading trends continue, what will happen to Baja California, San Diego, Los Angeles and Santa Cruz?:

These cities will continue to move northwestward along the Baja California microplate in a very short amount of time, given the divergence of plates across the area of hot week lithosphere along a tectonically active margin.

Which part of the United States sits in an opening ocean basin? Evaluate the earthquake threat there:

The San Francisco section of the San Andreas fault is positioned near an opening ocean basin and the other plates "locking" the fault in pose an ever-increasingly higher risk of a massive earthquake occurring there at some point in the future.

How long were the surface ruptures in the 1906 San Francisco and 1857 Fort Tejon earthquakes? What was the maximum offset of the ground surface during each quake?:

The 1857 one had a rupture of 360 km and maximum offset in the Carrizo Plain at 9.5 m. The 1906 one had surface displacement of up to 28 feet and a rupture distance of nearly 500 km.

Evaluate the earthquake hazards in locked versus creeping segments of the San Andreas fault. Are the biggest cities in locked or creeping segments?:

The biggest cities are in the locked part of the fault which poses the greater long-term risk for a potential very damaging earthquake.

Evaluate the seismic gap in the San Andreas fault south of San Francisco:

After the Loma Prieta earthquake in 1989, the gap became largely filled in. Prior to that, there was a gap in earthquakes in this area between 1969 and 1989. The theory is that there will be another massive gap filling process that takes place to overly fill the remaining small gap.

What factors combined to cause the resonance in Mexico City that was so deadly in the 1985 earthquake? How far was the city from the epicenter?:

There were multiple earthquakes with magnitudes ranging from 5-7 and Mexico City rests on an ancient lake bed, so many buildings and structures fell. The city was 320 km away from the epicenter.

Sketch a Marina District (San Francisco) dwelling and explain why so many failed during the 1989 Loma Prieta earthquake:

FIO

So many failed during the 1989 earthquake, because typical buildings were multiple stories tall and the first floor was built from soft materials usually with a garage with much open space.

What is usually the worst time of day for a big earthquake to strike a city in the Western United States?:

During rush hour is the worst time, given the severity of backup on the major highways in southern California. If many cars are on the major highways during a big earthquake, then the structures would fail and a great number of casualties would be incurred.

What are the four stages of formation (Wilson cycle) of an ocean basin?:

- Rifting of continents by mantle diapirism;

- Continental drift, seafloor spreading & formation of ocean basins;

- Progressive closure of ocean basins by subduction of ocean lithosphere;

- Continental collision and final closure of ocean basin

Can one large earthquake trigger others? What is the recent experience in Indonesia?:

One large earthquake can trigger subsequent other large and small earthquakes. In 2017 and 2018, there were a series of earthquakes correlated together all around 6 to 7 Mw in magnitude.

In the 2011 Japan earthquake, how large an area of plate moved? What was the maximum slip? What was the earthquake magnitude? When did the last earthquake of this size occur in the same area?

The magnitude was around 9Mw. The rupture length was nearly 500 km. The maximum slip was 40 m. The last earthquake of this size to occur in the same area happened in 2015.

What is the largest earthquake measured (see Chile)?:

In 1960, a 9.5 Mw earthquake was measured in southern Chile.

Why do so many mega-killer earthquakes occur in the China, India, Pakistan region?

These countries sit on the convergence zone between the South Asian and Eurasian plates, which are very mobile plates

megathrust fault

The 2010 Haiti and 1989 Loma Prieta earthquakes had similar magnitudes. Why were 3,400 times more people killed in the Haiti earthquake?

The buildings in Haiti have been in very poor standing since a massive earthquake in 1750 destroyed the initial settlement made by the French. After they gained their independence in 1804, they had to pay a great deal of reparations to nations that owned part of the country prior. So, there has been poor funding for building construction projects.

How can we recognize that an earthquake is a foreshock before the mainshock occurs?

Foreshocks are earthquakes that precede larger earthquakes in the same location. An earthquake cannot be identified as a foreshock until after a larger earthquake in the same area occurs, and it would have to be in a relatively short time span.

Sketch a sequence of cross-sections that show how a continent is split, then separated to form an ocean basin:

FIO

The ocean basin forms by way of the plates moving apart from one another, according to the Wilson cycle.

Natural disasters

An event or process that destroys life and/or property

Great natural disasters

A disaster so overwhelming that outside assistance is needed to handle the rescue and recovery for the region

Magnitude

An assessment of the size of an event. Magnitude scales exist for earthquakes, volcanic eruptions, hurricanes, and tornadoes.

Frequency

Number of events in a given time internal.

Return period

Amount of time between an event of a given size

exponential growth

Growth in a compound fashion that, given time, leads to incredible numbers

Demographic transitions

The change from a human population with high birth rates and high death rates to one with low birth rates and low death rates

fertility

The proportion of births to population

Mortality

The proportion of deaths to population

Carrying capacity

The maximum population size that can be supported under a given set of environmental conditions.

mantle

The largest zone of the Earth, comprising 83% by volume and 67% by mass.

Crust

The outermost layer of the lithosphere, composed of relatively low-density materials. The continental curst has lower density than oceanic crust.

Core

The central zone or nucleus of Earth about 2,900 km below the surface. The core is made mostly of iron and nickel and exists as a solid inner zone surrounded by a liquid outer shell. Earth's magnetic field originates within the core.

Viscous

Ease of flow. The more viscous a substance, the less readily it flows.

Lithosphere

The outer ridid shell of the Earth that lies above the asthenosphere and below the atmosphere and hydrosphere.

Asthenosphere

The layer of the Earth below the lithosphere in which isostatic adjustments take place. The rocks here deform readily and flow slowly.

Mesosphere

The mantle from the base fo the asthenosphere to the top of the core.

Isostacy

The condition of flotational equilibrium wherein the Earth's crust floats upward or downward as loads are removed or added.

ice sheet

A thick mass of ice that spreads out under its own weight and covers a huge area. Also known as a continental glacier.

Radioactivity

The breakdown of unstable atomic nuclei by emmision of particles or radiation. The decay process produces smaller atoms and gives off heat.

Tridal friction

Gravitational attraction between Earth, Moon, and Sun stretches the solid mass of the Earth and coverts some energy from Earth's rotation into heat.

Plate tectonics

The description of the movements of plates and the effects of plate formation, collision, subduction, and slide-past.