Science Unit 1 Fist actual test
P-waves speed up at the mantle-core boundary, so we know the outer core is less rigid than the mantle.
False
Modern seismometers record ground motions using electronic motion detectors. The data are then kept digitally on a computer.
True
Waves of energy radiate out from an earthquake's focus.
True
Oceanic crust is less dense than continental crust.
False
If the earthquake has a deep focus, the surface waves are the largest ones recorded.
False
Scientists cannot use seismic waves to understand what makes up the Earth's interior.
False
Scientists know for fact exactly how the earth and the solar system formed.
False
Scientists know that the mantle is made of rock because they have taken samples by drilling into it since the 1960's.
False
Scientists know that the outer core is liquid and the inner core is solid because S-waves go through the outer core.
False
The asthenosphere rides on the lithosphere.
False
The oceanic crust is thicker than the continental crust.
False
Although we sometimes refer to Earth's plates as being plates of crust, the plates are actually made of lithosphere.
True
An iron meteorite is the closest thing to a sample of the core that scientists can hold in their hands.
True
Ancient impact craters found on the Moon and inner planets indicate that asteroid impacts were common in the early solar system.
True
As the core heats the bottom layer of mantle material, particles move more rapidly, decreasing its density and causing it to rise.
True
Because continental crust is thick and has relatively low density, continental crust rises higher on the mantle than oceanic crust, which sinks into the mantle to form basins.
True
Convection currents within Earth's mantle form as material near the core heats up.
True
Early in the planet's history there were many radioactive elements.
True
Earth formed at the same time as the other planets.
True
S-waves are larger than P-waves.
True
Surface waves arrive last.
True
Surface waves travel along the ground, outward from an earthquake's epicenter and cause the most damage of any seismic wave.
True
The asthenosphere is partially molten upper mantle material and behaves plastically and can flow.
True
The asthenosphere is solid upper mantle material that is so hot that it behaves plastically and can flow.
True
The crust is very thin relative to the radius of the planet.
True
The definition of the lithosphere is based on how Earth materials behave.
True
The energy from earthquakes travels in waves.
True
Earth came together from the cloud of dust and gas nearly 4.6 billion years ago.
True
Earth's outer core is liquid.
True
Just as a medical doctor uses an MRI, CT scan, or x-ray to see inside a patient's body, seismologists use wave energy to learn about Earth's interior.
True
Oceanic crust is composed of mafic magma that erupts on the seafloor to create basalt lava flows or cools deeper down to create the intrusive igneous rock gabbro.
True
The different densities of earth's layers cause seismic waves to be reflected or refracted (bent.)
True
Wave height is used to determine the magnitude of the earthquake
true
A seismograph is a paper record of the seismic waves the seismograph received
False
As the mantle material rises closer to the crust it heats up even more.
False
Continental crust is mafic and oceanic crust is felsic
False
Earth has a brittle asthenosphere riding on the plastic lithosphere.
False
Earth was struck so much in its first 500 million years causing it to cool greatly.
False
P-waves and S-waves move in a compression/expansion type motion, squeezing and unsqueezing Earth materials as they travel.
False
Radioactive decay absorbs heat.
False
S-waves are the fastest.
False
S-waves travel through solids, liquids, and gases while P-waves only move through solids.
False
Seismic waves are measured on a seismogram.
False
Seismic waves go the same speed through different materials.
False
Seismic waves travel outward in one direction from where the ground breaks (focus).
False
Seismograms can only tell you how strong an earthquake is
False
Since Earth has a magnetic field, there must be a gas within the planet.
False
The Earth's strong magnetic field is caused by conduction in the liquid outer core.
False
The deepest drill hole into the earth reached its core.
False
The heat that keeps the outer core from solidifying is produced by the breakdown of radioactive elements in the crust.
False
The height of a wave from the center line to its crest is its wavelength while the distance between waves from crest to crest (or trough to trough) is its amplitude.
False
The mantle is hot mostly because of the heat conducted from the crust.
False
The mantle is mostly iron metal.
False
When Earth first came together it was really cold.
False
When Earth was entirely molten, gravity drew lighter elements to the center and denser elements rose to the surface.
False
Earth's overall density is higher than the density of crustal rocks, so the core must be made of something dense, like metal.
True
Every wave has a high point called a crest and a low point called a trough.
True
Geologists study earthquake waves to "see" Earth's interior.
True
Gravity caused small bodies of rock and metal orbiting the Sun to smash together to create larger bodies.
True
Gravity caused the temperature and pressure of the early earth to increase by squeezing the material in its interior really hard.
True
If a material is able to move, even if it moves very slowly, convection currents can form.
True
If we could cut Earth open, we'd see the inner core at the center, then the outer core, the mantle in the middle and the crust on the outside
True
P-waves (primary waves) are fastest, traveling at about 6 to 7 kilometers (about 4 miles) per second, so they arrive first at the seismometer.
True
P-waves and S-waves are known as body waves because they move through the solid body of the Earth.
True
S-waves disappear at the mantle core boundary, so we know the outer core is liquid.
True
Scientists know that the core is metal based on the overall density of the planet, metallic meteorites, and earth's magnetic field.
True
Some seismic waves do not travel through liquids or gases.
True
The lithosphere is composed of both the crust and the portion of the upper mantle and behaves as a brittle, rigid solid.
True
The lithosphere is composed of both the crust and the portion of the upper mantle that behaves as a brittle, rigid solid.
True
The mantle is made of iron and magnesium rich silicate minerals.
True
The mantle is made of solid rock and is very hot.
True
The outer core is molten metal.
True
The separation of Earth into layers based on density is known as differentiation.
True
The study of seismic waves is known as seismology.
True
The two types of crust are oceanic crust and continental crust.
True
S-waves cannot travel through liquid.
true
The liquid outer core creates an S-wave shadow zone on the opposite side of the Earth from the quake.
true