GEO 004 Midterm #1

The 4 A's of Migitation

Avoid, Accept, Anticipate, and Alter.

Calculating Slope

Slope \= rise/run

Find Contour Interval

Determine elevation difference between contours, Count \# of spaces between contours, elevation difference/ \# of spaces.

Numeric Scale

1:24,000

Verbal Scale

One inch equal four miles

Graphical Scale

Small ruler that can be used to convert distances covered on a map to real

3 things to find location on earth

Longitude, Latitude, and Elevation.

Longitude

Distance east or west of the prime meridian, measured in degrees.

Lattitude

Lines that run east and west dividing the earth.

Large Scale Map

Relatively zoomed in, shows more detail.

Small Scale Map

Relatively zoomed out, shows less detail.

Topographic map

A map that shows the surface features of an area. Gives information on our location and elevation. The study of the surface of the Earth.

Radioactive Decay

A spontaneous process in which unstable nuclei lose energy by emitting radiation. As they repeat decay they emit energy, energy loss happens gradually.

Sources of Internal Heat Energy

Impacts of asteroids and comets, gravitational energy, differentiation layers and decay of radioactive isotopes.

Types of Plate Boundaries

Divergent, Convergent, and Transform. Immense friction between plates, stress results in earthquakes.

Divergent Boundary

A boundary where plates pull away/ apart from each other, occurs in oceans mostly.

Convergent Boundary

A boundary where two plates push together, plates collide, a subduction zone.

Transform Boundary

A plate boundary is where two plates move in opposite directions and slide past each other. The most rare plate boundaries and our type of fault; San Andreas fault.

Evidence for Plate Tectonics

\-Shape of continents, Pangea

\-Rocks matching mountain belts

\-Location of found fossils

\-Seafloor magnetization

\-Earthquake locations correspond to plate boundaries

\-Volcanoes locations occur along plate boundaries

Volcanoes Hot Spots

Volcanic centers NOT near plate boundaries. Locations where narrow plumes of magma rise through the mantle in a fixed place over a long period of time. ex) Hawaii

Spreading Center

Lower viscosity, low volatility, large volume. A divergent boundary, marked by a rift at the crest of a mid-ocean ridge, where new oceanic crust is formed by seafloor spreading.

Calderas Volcano

Type of volcano:

High Viscosity

High Volatility

Very Large Volume.

Injection of magmas causes doming on surface, and dome collapses. Massive pyroclastic flows and lava flows. A large volcanic crater ex) Yellowstone.

Formation of Calderas Volcano

1) Injection of magma domes on surface
2) Fractures form, gas escapes, major ash falls
3) Dome collapses, caldera/ crater forms, lava flows
4) Injection of more magma, dome forms

Flood Basalts

Form when lava flows out of long cracks in Earth's crust. Low viscosity, high volatility, very large volume. Characterized by massive volume of magma, stretches of land or the ocean floor with basalt lava.

Viscosity

Resistance to flow, higher viscosity, the lower the flow \= more explosive eruption. In volcanic rocks viscosity is a function of silica, SiCO2.

Volatility

Dissolves gas in magma, the more dissolved water \= more explosive eruption. The tendency of a substance to vaporize.

Volume

Refers to the amount of magma being stored inside the volcano. Size of magma chamber, more magma \= more erupted material.

Matters for eruption type

\-Location

\-Way you melt (depressurize, temperature, water)

\-What you melt (crust with low or high SiCO2)

\-Determine chemistry and eruption type

\-Are both functions of tectonics in a region

Prediction/ Mitigation

Recording and learning from past volcanic eruptions to help determine when the next eruption will happen.

How to predict volcanic eruptions

\-Monitoring gas emissions

\-Ground deformation

\-Presence of earthquakes/ seismic activity

Volcano Watch vs Warning

Watch - Volcano is exhibiting increased potential but poses limited hazards. Warning - Hazardous eruption is imminent, underway, or suspected. ex) Ingredients for a taco vs making and assembling a taco

What kind of plates do we live?

We live in the vicinity of the boundary between the North American and Pacific plates. It is transform plate boundary. San Andreas fault.

Types of faults

Normal, Reverse, and Strike-slip.

Normal fault

A type of fault where the hanging wall slides downward; caused by tension in the crust. Extensional setting, hanging wall moves down.

Reverse fault

A fault in which the hanging wall moves up relative to the footwall. Compressional setting, hanging wall moves up.

Strike-slip fault

Due to Shear. A type of fault where rocks on either side move past each other sideways with little up or down motion. Push together: creates hills/ mountains. Pull apart: creates holes, basins.

Right lateral Strike-slip fault

Strike-slip fault. As you face the fault, the opposite side of the fault moves to the right.

Left lateral Strike-slip fault

Strike-slip fault. As you face the fault, the opposite side of the fault moves to the left.

Dip Slip Fault

Due to Tension/ Compression. A fault in which the movement is parallel to the dip of the fault. Vertical movement.

Seismic waves

Travel from where earthquakes happen, rupture releases energy waves through the earth. Wavelength, Travel direction, and Amplitude.

Seismometer/ Seismograph/ Seismogram

Seismic waves are measured with a Seismometer.
The recorder used to measure waves is referred to as a Seismograph.
The recording made is called a Seismogram.

Amplitude

Height of seismic wave. Related to the strength of shaking.

Wave length

Distance between waves.

Period

Time between waves, measured in seconds.

Frequency

Number of waves passing through a fixed point during 1 seconds time, measured in hertz, period \= 1/frequency.

P waves

A type of seismic wave that compresses and expands the ground. Always arrive first.

S waves

A type of seismic wave that moves the ground up and down or side to side. Same rest as p waves, secondary waves.

Love waves

Surface waves that shear the ground in a horizontal direction. Can only travel through solids. Third to arrive.

Rayleigh waves

Surface waves that travel in a backward

Why do earthquakes vary?

Propogation/ changes in amplitude is realted to:

\-Geometrical spreading

\-Attenuation

\-Rock Type

\-Earthquake magnitude

Geometrical Spreading

Energy has to be spread over larger era as the distance from the source increases.

Attenuation

Loss of energy with distance due to scattering and friction. Friction between mineral grains dissipate energy and reduce amplitude. The longer wave travels the more energy is lost.

Rock Types

Different rocks have different frictional properties. East coast felt larger distance. Sediment or soil? Sediment: Soft, ground easily moves. Bedrock: Hard, ground does not move a lot.

Site effects

Properties of soil and rock around you. Sediment sites amplify seismic waves. Ex) Bowl of Jello

Liquefaction

The process by which an earthquake's violent movement suddenly turns loose soil into liquid mud. 3 Factors
1) Loose granular sediment
2) Water saturated
3) Strong shaking

Magnitude

Measure of the energy released during an earthquake. Bigger the earthquake, the more energy emitted, and the rarer it is. Measured on the richter scale.

Seismic Hazard Steps

Step #1: Consult map to determine risk for shaking

Step #2: Design buildings and structure to withstand shaking

Step #3: Preventing injuries from falling contents Step #4: Plan and prepare.

Subduction Zone

Occurs at Convergent Plate Boundary. The region where oceanic plates sink down into the asthenosphere.

Types of Magma

Basalt, Andesite, and Rhyolite.

Igneous Rock Types SiCO2

Decreasing Silica content increasing dark, heavy minerals.

Volcanism Control by the Three V’s

Viscosity + Volatiles + Volume = Volcanic Landforms.

Released

As radioactive atoms decay, energy is __?

Chemical; Physical

The Earth's innermost layer is known as the core when considering ___ properties, but is broken into 2 layers, outer core and inner core, when discussing ___ properties.

Subduction Zone

When oceanic lithosphere collides with another plate, the older, colder plate goes beneath the younger, warmer plate This is known as the __?

Seafloor spreading

After lava cools, atoms in iron-bearing minerals on the seafloor become magnetized in the direction of the Earth's magnetic field at that time and place.

Rates of plate movement

Movement comparable to those of human fingernail growth?

Hot spots

_____ have active volcanoes above them on the Earth's surface and moving plates carry the volcanoes away from their hot-spot source.

True

T/F: The movements of the lithospheric plates are directly responsible for the vast majority of the earthquakes, volcanic eruptions, and mountains on Earth.

True

T/F: A graphical scale is a small ruler included on a map that can be used to convert distances covered on a map to real-world distances.  A  numeric scale is a ratio defining the conversion factor between distance measured on a map and real-world distance.

3 Elements; Longitude, Latitude and Elevation.

How many elements (1, 2, 3, 4, etc) do you need to define your location on the Earth's surface?

Contour Lines

Flat, two-dimensional maps are great for showing your location in terms of north-south and east-west directions.  What map features are used to show your vertical (up-down) position?

False

T/F: ALL Volcanoes tend to occur mostly along plate boundaries. (Hot spots do not)

Intraplate Volcanoes

“Intraplate” means within the interior of a tectonic plate. Volcanoes that takes place away from the margins of tectonic plates.

Yellowstone

When a mantle plume rises up through a continental plate, it may form a continental caldera/ Super Volcano such as _____.

**Volatile-rich**

Subducting plates bring water saturated sediments into the mantle , which results in partial melting and generation of ____ melt.

Increasing

As magma rises through continental crust, partial melting of the continental crust ______ing the SiO2 content and viscosity of the magma, eventually forming andesitic-rhyolitic magmas.

Divergent and Convergent

Volcanos occur at ___ plate boundaries?

False

T/F: The three Vs of volcanology are viscosity, volatiles, velocity

False

**T/F:** Shield volcanoes are steep-sided, symmetrical volcanic peaks built of alternating layers of pyroclastic debris capped by high-viscosity andesitic to rhyolitic lava flows.

True

T/F: A caldera collapse occurs after the magma chamber is mostly empty

True

T/F: The most peaceful eruptions are Icelandic type eruptions

True

T/F: Slow flowing, more viscous basaltic lava commonly has a rough, blocky texture called A’a.

True

T/F: In addition to lava flows, volcanic processes can cause tsunamis, debris avalanches, and lahars.

False

T/F: The primary cause(s) of death from explosive volcanic eruptions is lava flows.

Pyroclastic flows

Destructive mass of very hot ash, lava fragments, and gases ejected explosively from a volcano at great speed. Primary cause of death from volcanic eruptions.

Precursors of volcano eruption

Several geologic phenomena are considered precursors of an impending volcanic eruption. These include seismic waves, ground deformation, and the release of gases.

Vulcanian Eruptions

Type of Erruption:

Occur at convergent boundary.

Moderate-high viscosity lava

Moderate-high volatiles

Moderate volume (ash falls, etc.) Dangerous!

Plinian Eruptions

Type of Erruption:

Occur at convergent boundary or continental-hot spot

High viscosity lava

High volatiles

High volume

Large stratovolano or supervolcano major ash falls, pyroclastic flows, Gooey lava, lahars. Very dangerous!

Hawaiian Eruptions

Type of Erruption:

Occur at hot spots erupting through oceanic crust

Low viscosity lava

Low volatiles (dissolved water).

Relatively high volume

Runny, erupt continuously at low rate known for extensive lava flows “not very dangerous”.

Strombolian Eruptions

Type of Erruption:

Occur at convergent boundary

Moderate viscosity lava

Moderate volatiles (dissolved water)

Low-moderate volume

Somewhat runny, erupt nearly continuously at low rate known for volcanic bombs not especially dangerous.

Stratovolcano

Type of Volcano:

Med/high Viscosity, med/high

Volatility, large Volume. Also known as composite

volcanoes. High viscosity lava flows --> This is what

gives them their steep sides.

Shield Volcano

Type of Volcano:

Built up in from low viscosity, low volatility, large volume flows--> This is what gives them their gentle slopes, large size.

True

T/F: Due to the tilt of the Earth on its axis, differential heating occurs resulting in the equatorial regions of Earth receiving more solar energy than the polar regions.

How to make magma?

Lowering pressure, Raising temperature, Adding water. Melt/ magma travels through rock with little SiO2, magma contains low SiO2.

Resistance to flow,

Dissolved gases,

Explosive

Viscosity refers to a materials _____. While volatiles refers to the _____. Higher viscosity and more volatiles lead to more ____ erruptions.

Solar Radiation

Which of the following is NOT a primary source for plate tectonics?

Solar Radiation

Radioactive Decay

Impact Energy

Gravitational energy from earth differentiation

Inner Core

(Solid)

Identify Layers of the Earth:

What is E?

Outer Core

(Liquid)

Identify Layers of the Earth:

What is D?

Mesosphere

(stiff plastic)

Identify Layers of the Earth:

What is C?

Athenosphere

(Ductile, soft plastic)

Identify Layers of the Earth:

What is B?