Plate tectonics, Earthquakes, and Volcanoes

Alfred Wegener

A German scientist who proposed the theroy of continental drift

Collision Boundary

A converging boundary that is formed when 2 continents collide & are welded into a single, larger continent, creating mountains

Seismograph

A device that records ground movements caused by seismic waves as they move through Earth

Viscosity

A liquid's resistance to flowing. This is impacted by amount of silica in a magma and the temperature of magma.

Shield Volcano

A low, flat, gently sloping volcano built from many flows of fluid, low-viscosity basaltic lava

Mercalli Scale

A scale that rates earthquakes according to their intensity and how much damage they cause at a particular place

Cinder Cone

A steep, cone-shaped hill or small mountain made of volcanic ash, cinders, and bombs piled up around a volcano's opening

Composite Volcano

A tall, explosive, cone-shaped volcano formed by layers of silica-rich lava and ash.

Seismogram

A tracing of earthquake motion that is created by a seismograph

subduction zone

A type of convergent boundary where one more dense plate sinks beneath another. Forms Volcanoes and Trenches

hotspot

A weak spot in the middle of a tectonic plate where magma surfaces; forms a volcano (ex: Hawaii & Yellowstone)

Primary (P) wave

Earthquake bodywave that arrives first, and can be transmitted through both solids and liquids

S-P interval

In earthquake seismology, the time interval between the first arrivals of transverse (S) and longitudinal (P) waves, which is proportional to the distance from the earthquake source.

Harry Hess

Proposed the theory of sea-floor spreading

Richter Scale

Scale used to measure the power or magnitude of energy released during an earthquake

Secondary (S) waves

Seismic waves that can move up and down or side to side, and can only travel through solids. They are second to arrive at a seismic station.

epicenter

The location where seismic waves first reach the surface.

asthenosphere

The plastic region of the mantle just below the lithosphere, convection currents here are thought to cause plate movement.

Surface Waves

These are what P Waves and S Waves become when they reach the surface, they can produce severe ground movements. These get to the station last. Two Types: R-Waves (Rayleigh Waves), and L-Waves (Love Waves)

plate boundary

Where two tectonic (lithospheric) plates meet, and where most major volcanoes and earthquakes occur.

fault line

a break or crack in Earth's surface. Caused by shifting and moving plates.

Rift Valley

a deep valley that forms on continents where two plates move apart. Caused by a divergent boundary

Ocean Trench

a long steep-sided depression in the ocean floor caused by one plate sinking below another.

tectonic plate

a piece of the lithosphere that moves around on top of the asthenosphere due to mantle convection currents

divergent boundary

a plate boundary where two plates move away from each other

Transform Boundary

a plate boundary where two plates move past each other in opposite directions

convergent boundary

a plate boundary where two plates move toward each other

Mid-Ocean Ridge

an underwater moutain chain where new ocean floor is formed. Caused by Divergent Boundary

volcano

area of the Earth's crust (lithosphere) where magma has come to the surface. Caused by convergent plate boundaries or Hot Spots.

convection currents

circular movement of a substance due to changes in temperature and density

oceanic crust

earths crust located under the ocean. The thinnest type of crust. Mostly basalt

Pangaea

large, ancient (200MY old) landmass that was composed of all the continents joined together. Supercontenent

outer core

liquid metal layer deep inside earth

lava

magma that reaches the earth's surface

magma

molten (melted) rock beneath the earth's surface

Pacific Ring of Fire

region around the Pacific Ocean where most of the volcanoes and earthquakes on Earth occur regularly

tsunami

seismic sea wave that begins over an earthquake focus and can be highly destructive when it crashes on shore

inner core

solid metal layer in earths core

continental crust

surface layer above sea level, the part of the Earth's crust that comprises the continents, which has an average thickness of 45km; primarily composed of granite

mantle

the layer of the earth between the crust and the core, Is located beneath the earths crust. Part of the mantle consists of the molten material that circulates in convection currents beneath the earths crust. This process drives plate tectonics.

focus

the point far below, inside the Earth where an earthquake begins

earthquake

the shaking of earth surface produced by the rapid release of energy in earths crust. Caused plates shifting. Found along all plate boundaries.

Amplitude

the size of the wiggles on an earthquake recording.

lithosphere

the solid part of the earth consisting of the crust and outer mantle

plate tectonics

the theory that pieces of Earth's lithosphere are in constant motion, driven by convection currents in the mantle

crust

the thin and solid outermost layer of the Earth above the mantle

mantle convection currents

the transfer of thermal energy (heat) from the core by the circulation or movement of Mantle material. Believed to be the driving force of plate tectonics.

Continental Drift

theory proposed by Alfred Wegner that states that there was a supercontinent that split into the continents of today.

seismic waves

wave generated by an earthquake.Primary (first,push/pull), Secondary (side to side), Surface (slowest, destructive)

sea-floor spreading

when two oceanic plates pull apart, magma rises and new crust is formed on the ocean floor