Science - volcanoes, earthquakes Flashcards
epicenter
point of Earth’s surface directely above an earthquake’s focus
focus
in an earthquake, the point beneath Earth’s surface where energy release occurs
magnitude
measure of the energy released by an earthquake
mantle
largest layer inside Earth, lying directly above the outer core and that is made mostly of silicon, oxygen, magnesium, and iron
outer core
liquid core that surrounds Earth’s solid inner core, and that is made mostly of iron
primary waves
waves that travel outward from an Earthquake’s focus and cause particles in rocks to move back and forth in the same direction the wave is moving
reverse fault
break in rock due to compression forces, where rocks above the fault surface move upward and over the rocks below the fault surface
secondary waves
waves that travel outward from an earthquke’s focus and move through Earth by causing particles in rocks to vibrate at right angles to the direction of the wave
seismic waves
energy waves that are produced at and travel outward from the earthquake’s focus
seismograph
device used by seimologists to record primary, secondary, suface waves from earthquakes
seismologist
scientist who studiesearthquakes and seismic waves
strike-slip fault
break in rock due to shearing forces, where rocks on either side of the fault suface move past each other with little upward or downward movement
athenosphere
plastic-like layer below the lithosphere
continental drift
hypothesis proposed by Alfred Wegener that the states that continents have moved slowly to their current locations on Earth
convection current
cycle of heating, rising, cooling, and sinking that is thought to be the force behind plate tectioncs
lithosphere
rigid, outermost layer of Earth that is about 100km thick, and is composed of the crust and part of the upper mantle
pangaea
single large landmass made up of all the continents connected together that broke apart 200 million years ago
plate
surface along which rocks break and move
plate tectonics
theory that Earth’s crust and upper mantle are broken into sections that move around on a plastic-like layer of the mantle
seafloor spreading
theory that magma from below Earth’s crust is forced upward toward the surface at a mid-ocean ridge, flows from the cracks as the seafloor spreads apart and bcomes solid as it cools, forming new seafloor
surface waves
waves of energy that reach Earth’s surface during an earthquake, travel outward from the epicenter, and move rock particles up and down, and side to side