EAPS Exam 2

Why Neptune has a magnetic field.

Water and ammonia mix conducts electricity very well. Combined with the rotation of the planet, it allows magnetic fields to form much stronger than earth's magnetic field

What causes hot rocks to melt at subduction zones.

Water is pushed out from the subducting plate lowers the melting temperature of the hot mantle above causing it to melt

Why Pluto is still hot inside.

We are not sure

Where giant flood basalts originate from.

When hot spot mantle plumes first protrude to the surface

What causes hot rocks to melt at hotspots.

When the hotspot plume head reaches the base of the lithosphere, it begins to melt by depressurized melting, causing massive volcanism.

What volcanic ash is

broken, ejected shards of gas bubbles

The state (solid/liquid) of each layer in the Earth

mantle: solid, outer core: liquid, inner core: solid.

How a stratovolcano forms.

stratovolcanoes form through explosive eruptions depositing material near a central vent.

What a magnetosphere is.

A region where a planet's magnetic field is the predominant magnetic field

How much of the Earth's mantle is actually melted rock

A small percentage

Why the Sun has a strong magnetic field

Abundance of freely moving electrons, spins slowly so its magnetic field is often disorganized sometimes having two magnetic north poles

How a cinder cone forms.

Air cooled magma is thrown out of an open column

What viscosity is a measure of.

How easily a fluid flows, low viscosity magma can easily find its way to the surface through cracks in the overlying rock, high viscosity magma will get stuck

Why most craters on the Moon are round.

Impacts act as explosions so mostly round craters, ejecta can get blown out one way or another, but crater will still be round

The relative size of different crater morphologies.

Increasing crater size (bigger or faster impactor) causes a transition from a simple to a complex crater geometry As craters get bigger, they transition into peak-ring basins and then multi-ring basins

Why Jupiter has a magnetic field.

Jupiter has a very strong magnetic field (14 times that of earth's) caused by convection in its electrical conducting metallic hydrogen outer core and a fast planet rotation (9 earth hours) Jupiter's intense magnetic field generates the solar systems largest and brightest auroras, which are 1000 times larger than earth's auroras.

How a caldera forms.

Large circular depression forms when the surface collapses into an emptying magma chamber. Not formed by ejecting the surface material, though they are often accompanied by the formation of smaller eruption craters that serve to remove subsurface material.

The least and most powerful types of volcanic eruptions.

Least: Hawaiian volcano lava fountain, strombolian, vulcanian, palean, plinian :most

Where Earth's magnetic north pole is really located.

(it is always moving) right now it is moving towards russia above Canada, Magnetic north pole = geographic south pole

The 3 ways to get hot rocks to melt.

1. Increase temperature: however it is difficult to heat rocks up in place, so this is not a mechanism that induces volcanism. 2. Decrease pressure (called depressurized melting): this reduces the melting temperature and rocks always experience a decrease in pressure as they rise closer to the surface. 3. Add water to the mineralogy (hydration-induced melting): this breaks up long silica chains, which reduces the rock's melting temperature

The order of impact processes.

1. contact/compression 2. Excavation 3. modification

The typical range of speeds of asteroid and comet impacts.

11 km/s

Why Venus does not experience plate tectonics.

2 possibilities. 1 being venus is so hot (closer to the Sun and its atmosphere retains a lot of that heat) that its lithosphere may slowly flow rather than break into plates. 2 being venus is so dry that it's lithosphere is too strong to break

Why there are thrust faults on Pluto.

A Cooling subsurface ocean causes the crust to expand which causes normal faults

The factors that control how much gas pressure builds below the surface

Amount of magma: the more magma the more dissolved gas Amount of dissolved gas: the more gas the potential for great explosion Viscosity of the magma

What an effusive volcanic eruption is.

An effusive volcanic eruption is an eruption in which magma can flow to the surface through a vent or crack without building up high pressure.

How to increase the strength of an induced magnetic field.

An electric current, the higher the current the stronger the magnetic field. Also, coiling the wire will make it stronger. Then even STRONGER if the coil surrounds a piece of metal like iron

What is required to generate a planetary dynamo.

An electrical conducting liquid layer that is convecting Convection in this conducting layer is organized into coils by planetary spin These coils spiral around more conducting material, thus greatly increasing the strength of the magnetic field

What cryovolcanism is.

An eruption of water or ices, such as nitrogen, ammonia, or methane, instead of molten rock.

What a mid-ocean ridge is.

Area where two plates collide and push together to form new ocean lithosphere

What a subduction zone is

Area where two plates meet and one is pushed under the other. This plate is then melted and reused later.

What a transform fault is

Area where two plates slide past each other along the surface

How accretion leads to heat.

As planets collect pieces of material, the pieces slam into the planet creating energy and heat

Why impacts intao Mercury are faster than the other terrestrial planets.

Asteroids and comets hit Mercury faster because of the Sun's position and gravitational assistance.

The geometry of simple craters.

Bowl shaped filled/lined with impact rock (breccia) much smaller with distinct rim

Why comets impact faster than asteroids.

Comets are from farther out in the solar system so they spend more time being accelerated toward the inner solar system by the sun's gravity

The mediums by which conduction, convection, and radiative heat transfer move heat.

Conduction- the transfer of heat through a solid by the spread of vibrations. Ex: putting an end of a metal rod in fire, eventually it will reach the other end Convection- the transfer of heat through fluid motion Radiation- transfers through electromagnetic waves through a transparent medium

What drives plate tectonics.

Convection in the mantle

The size of impact craters compared impactor size.

Craters can be 10-30 times larger than the impactors, since impacts cause a shock wave that vaporizes, melts, fractures, and ejects material in the impact zone.

Consequence of a planet or moon being hot inside.

Differentiation, magnetic fields, plate tectonics, and volcanism.

How Earth's internal temperature compares to that of the surface of the Sun.

Earth's core is the same temperature as the surface of the sun

What the minimum impact velocity of an asteroid or comet depends on

Escape velocity of the body being impacted

The geometry of complex craters.

Flatter with bump up in the middle, sides are more terraced

What contributes to the current internal temperature of the Earth.

Half from radioactive decay, half from primordial sources (accretion and core formation)

Why Lord Kelvin's calculation of the age of the Earth did not work

He did not take into account radioactive decay

What is meant by primordial heating.

Heating that occurred early during a planet's formation

The combination of magma viscosity and gas content is most likely to lead to explosive eruptions.

High viscosity and high gas content leads to explosive.

The components of an eruption column.

Highest: Momentum-Driven, Umbrella region, Convective ascent, Gas thrust :Lowest

Which type of volcanism is observed on the other terrestrial planets

Hot spots (Lecture 9/29)

Why smaller planets cool faster than larger ones.

Less primordial heat (less impacts, smaller core), less radioactive elements to keep them hot, and smaller bodies have larger surface areas to volume ratios, enabling them more efficiently get rid of heat (mostly due to this last statement)

How each layer within the Earth transfers heat.

Lithosphere (solid) : conduction Mantle (solid): convection Outer core (liquid): convection Inner core (solid): conduction

The kinds of volcanoes low viscosity magma lava leads to.

Low slope, not tall

The difference between magma and lava.

Magma is melted rock and it is located underneath the ground. When that melted rock reaches the surface it is called lava. (9/29 Lecture) Chapter 3 in textbook

Why pressure in magma builds as it rises toward the surface

Magmas contain dissolved gas in solution form, as magma moves up to the surface the pressure on it from overlying rocks decreases which causes this dissolved gas expands to form gas bubbles, gas takes up more volume than solution causing pressure to build in magma.

What protects us from the solar wind.

Magnetic field and the atmosphere

Which flood basalts on the Moon are primarily only found in large impact basins.

Mare (Dark patches on Moon)

Why ejecta blankets on Mars look fluidy.

Mars has a thick permafrost layer (subsurface ice)

Why Olympus Mons is so big.

Mars has ⅓ the gravity of Earth. There are no plate tectonics on Mars. Mars also does not have significant erosion processes. Sits on a hot spot and never leaves

The tallest mountain on Earth as measured from its base to its peak.

Mauna Kea in hawaii. Not Everest!

Which planets are covered by flood basalts.

Mercury, Venus, Mars

The tell-tale signs of plate tectonics.

Mid oceanic ridges and subduction zones

Which other terrestrial planets currently exhibit plate tectonics.

None except earth

Why impact speeds into the Earth and Moon are similar.

Objects hitting the moon get an assist from earth's gravity

How far an ejecta blanket generally extends.

One crater diameter

The difference between radioactive decay and radiative heat transfer.

Radiative heat transfer is when heat is transferred through electromagnetic waves (light) through a transparent medium. Only takes place at the surface of a planet and is the only means for a planet to shed heat into space.c Radioactive decay: The nucleus of an unstable atom transforms into a stable one by throwing off neutrons or protons, causing collisions

Where strike slip faults are found besides Earth.

Rarely observed on any other planet since no other planet utilizes plate tectonics to shed its interynal heat (Jupiter's moon Europa, Ganymede)

What the Ring of Fire refers to.

Ring of volcanoes caused by subduction zone volcanism around the pacific rim The Ring of Fire refers to the area where ___ is surrounded by subduction zones.

How one can most easily sample the subsurface ocean of Enceladus.

Sample a water vapor plume

What lithosphere is.

Strong outer shell of the Earth consisting of the strong crust and upper mantle

What causes auroras.

The deflection of the solar wind by the magnetic field directs charged particles to our poles, which excites the nitrogen and oxygen in our atmosphere

The primary source of Jupiter's moon Io's internal heat.

The elliptical orbit causes gravity between the two to constantly vary elongating and shortening (100m) causing heat

How planet mass and radius influence a planet's escape velocity.

The greater the mass of the planet the higher the velocity needed to escape gravity. The greater the radius of the planet the lower the velocity needed to escape gravity.

Why hotspots on Earth lead to hotspot tracks?

The hotspots don't move but the plates above them do. As the plate moves the hotspot continues to leak magma to the surface creating a track. Idk something like that??

Why there are thrust faults on Mercury and The Moon.

The interiors are cooling, so the surface contracts and causes thrust faults

The lava fountains have been observed on Io.

The lava is so hot that it appeared white on camera.(incomplete)

The kind of volcanoes found on Mercury.

The lava on Mercury has such a low viscosity that volcanoes do not form. "Ghost craters" are filled fissures of lava.

How gravity influences an eruption column

The less the force of gravity, the higher the eruption column can go.

What a transient crater is

The max size of crater that is at the end of the excavation stage. It cannot sustain cuz of lack of support and collapses afterwards in the modification stage

How radioactive decay produces heat.

The nucleus of an unstable atom transforms into a stable one by throwing off neutrons or protons, causing collisions

How core formation leads to heat.

The primary contributors to heat in the core are the decay of radioactive elements, leftover heat from planetary formation, and heat released as the liquid outer core solidifies near its boundary with the inner core.

What happened to Venus' surface about 500 million years ago.

The surface of the planet was catastrophically resurfaced by volcanism

Why there are fewer active volcanoes in the U.S. southwest compared to the northwest.

There are fewer active volcanoes in the U.S. southwest compared to the northwest because there are no active subduction zones in the southwestern U.S. (Lecture 9/29)

Where cryovolcanoes are found on Earth.

There are no readily identifiable cryovolcanoes on Earth.

What happens to atoms when they heat up

They vibrate faster

How conduction transfers heat.

Through a solid by the spread of vibrations

How convection transfers heat.

Through fluid motion (solid state convection: if the solid behaves like a fluid)

What the asthenosphere is.

Underlies the lithosphere and is hot enough to flow like a fluid (even though it remains a solid).

Why Venus volcanoes are so flat.

Venus has a much denser atmosphere compared to Earth

Why Venus does not have a magnetic field.

Venus spins very slowly (1 Venus day takes 243 Earth days), so convection in its core does not organize itself into spirals (im not done)