Volcanoes & Magma
A molten mixture of rock forming substances, gases, and water.
What is magma?
What do scientists use to "see" the interior of the earth?
Earthquake waves (seismic waves) - specifically S- and P-waves.
What are seismic waves, and how do they carry energy from an earthquake?
Seismic waves are vibrations that travel through the Earth, carrying energy released during an earthquake.
Where is sea floor the oldest? the youngest?
Oldest by the continents, youngest in the middle.
What are the two types of plates?
Oceanic plates and continental plates
Why does magma rise to the surface?
It is less dense than the surrounding rock.
Describe the asthenosphere.
The asthenosphere is soft and plastic like, and is the layer that allows the continents to move.
The location on the surface of the earth directly above where the earthquake happened.
What is an earthquake epicenter?
Where is the sea floor the hottest? the coldest? Why?
Hottest in the middles, coldest by the continents, because there are volcanoes along the middle.
What landforms occur at convergent plate boundaries?
Mountains, volcanoes, oceanic trenches
This volcanic belt, circling the Pacific Ocean, contains most of Earth's volcanoes.
What is the Ring of Fire?
Where does Earth's internal heat come from?
Radioactive substances breaking down.
The area underground where the earthquake actually happens.
What is an earthquake focus?
Where did scientists look to find proof of sea floor spreading?
Mid ocean ridges.
What is subduction and where does it occur?
Subduction is when an oceanic plate gets pushed under another plate (continental or oceanic), and sinks into the mantle. It occurs along plate boundaries.
These volcanoes form at a fixed point in the mantle, away from plate boundaries, creating islands like Hawaii
What are hot spot volcanoes?
What causes convection currents inside the earth?
Heat from the outer core.
What are the three types of seismic waves, and in what order do the waves reach a seismograph?
P-waves, S-waves, and Surface waves, in that order.
What process at mid-ocean ridges causes new oceanic crust to form and push older crust outward?
What is magma rising from the mantle, cooling, and solidifying to create new seafloor?
What is a rift valley and where do they form?
A rift valley is a valley created by a continental plate being pulled apart by forces in the earth's crust. They form at divergent plate boundaries on land.
A volcano shaped like a large cone, and formed from alternating layers of lava and other rock types.
What is a stratovolcano?
Define convection.
Convection is the transfer of heat through the movement of fluids - liquids or gases.
What is the moment magnitude scale, and how does it differ from the Richter scale?
The moment magnitude scale estimates the total energy released by an earthquake and works for earthquakes of all sizes, while the Richter scale measures the size of seismic waves and is better suited for small, nearby quakes.
Who was the scientist that discovered that the oceans were shallowest in the middle and deepest near the continental margins?
A. Alfred Wegner
B. Robert Oppenheimer
C. Henry Hess
D. Isaac Newton
C. Henry Hess
What is ridge push and slab pull, and where do each of them occur?
Ridge push is the force created from new material being generated at mid ocean ridges, slab pull is the force created by the sinking part of subducting oceanic plates.
Ridge push occurs at mid ocean ridges, slab pull occurs at subduction zones.