Earthquakes and Volcanoes Flashcards
What are Earthquakes?
the vibrations in the ground that result from movement along breaks in Earth’s lithosphere
Where do most earthquakes occur?
In the ocean and along the edges of continents. Mainly along plate boundaries.
What causes earthquakes?
Earthquakes result from the buildup and release of stress along active plate boundaries.
Where do the deepest earthquakes occur?
Along convergent plate boundaries because the denser oceanic plate subducts into the mantle. They usually release a lot of energy and can be quite disastrous.
Where are shallow earthquakes found?
Along divergent plate boundaries like the mid-ocean ridge system, or along transform plate boundaries like the San Andreas Fault.
What is a fault?
A break in the Earth’s lithosphere where one block of rock moves toward, away from, or past another.
What are the three different types of motion found along faults?
Sliding horizontally past each other in opposite directions (strike-slip fault and transform plate boundary)
Pulling two blocks of rock apart (Normal fault and divergent plate boundary)
Pushing two blocks of rock together (Reverse fault and convergent plate boundary)
What type of motion is found along a reverse fault?
pushing two blocks of rock together
What is rock deformation?
When forces, such as pressure, are applied to rock and the rock changes shape.
what is a primary wave
Also called p-waves, cause particles in the ground to move in a push-pull motion similar to a coiled spring. Fastest moving seismic wave. first waves felt following an earthquake. travel through solids and liquids.
what is a secondary wave
also called s-waves. slower than p-waves. cause particles to move up and down at right angles relative to the direction the wave travels. can travel through solids only
what is a surface wave
cause particles in the ground to move up and down in a rolling motion similar to ocean waves. only travel on Earth’s surface closest to the epicenter. cause most damage to the surface of the Earth
what is a seismic wave
energy that travels as vibrations on and in Earth
what is a seismogram
a graphical illustration of seismic waves that records ground motion
what is a seismometer
an instrument that measures and records ground motion and can be used to determine the distance seismic waves travel.
what is a seismologist
scientists that study earthquakes
what is the epicenter
The location on Earth’s surface directly above the earthquake’s surface
what is the focus
where seismic waves originate where rocks first move along the fault, at a location inside Earth
what is the mantle
the thick middle layer in the solid part of Earth
what is a convergent plate boundary
the boundary between two plates that moves toward each other
Where do volcanoes form?
Along convergent plate boundaries, divergent plate boundaries, and hot spots.
What is the Ring of Fire?
An area of earthquake and volcanic activity that surrounds the Pacific Ocean
What happens when mantle melts?
It forms magma. The magma is less dense than the mantle and rises through the cracks in the crust. This forms a volcano.
What determines a volcano’s eruption style?
The magma chemistry. The amount of dissolved gases, specifically the amount of water vapor, a magma contains, and silica.
What determines the viscosity of magma?
the amount of silica in a magma. If it has a high silica content it has a high viscosity and flows like sticky toothpaste. If it has low silica content it has a low viscosity and flows easily like warm maple syrup.
Explain the difference between shield volcanoes and composite volcanoes?
shield volcanoes are common along divergent plate boundaries and oceanic hot spots. they are large with gentle slopes and basaltic lavas. Composite volcanoes are large, steep-sided volcanoes that usually result from explosive eruptions of andesitic and rhyolitic lava and ash along convergent pate boundaries.
Molten rocks erupts from a _______
volcano
______ is molten rock that flows along Earth’s surface
lava
A ________ is not associated with any plate boundary
hot spot
A ________ is large and steep-sided, occurs along convergent plate boundaries, and results from explosive eruptions
composite volcano
______ have gentle slopes of basaltic lava; they are commonly located along divergent plate boundaries and ocean hot spots
shield volcanoes
A _______ is small and steep-sided, and it erupts basaltic lava
cinder cone
_____ is present beneath Earth’s surface
magma
When magma erupts explosively, it can send particles of rock and glass, or _____ into the air
volcanic ash
Magma’s resistance to flow is called its _____
viscosity
Magma contains _____ gases, including carbon dioxide and sulfur dioxide
dissolved
A(n) ________ is a vent in Earth’s crust through which molten rock flows.
volcano
Molten rock below Earth’s surface is called _____
magma
Volcanoes can form along ______ plate boundaries, when one plate subducts under another.
convergent
Magma from the hot _____ rises through cracks in the crust and forms a volcano
mantle
Molten rock that erupts onto Earth’s surface is called _____
lava
At ______ plate boundaries, magma rises in cracks between the two plates forming volcanoes
divergent
Volcanoes that are not associated with plate boundaries are called ______
hot spots
Geologists theorize that hot spots form over ______, which are places where hot magma rises due to convection currents in the mantle.
plume
Most volcanoes occur on or along ______
plate boundaries
The _____ is the area of earthquake and volcanic activity that surrounds the Pacific Ocean
Ring of Fire
Most volcanoes in the United States occur near the ______ coast.
West
_____ are small, steep-sided volcanoes that erupt gas-rich, basaltic lavas
cinder cones
_____ are large, steep-sided volcanoes that result from explosive eruptions of andesitic and rhyolitic lava along convergent plate boundaries
composite volcanoes
______ are large, gentle-sloped volcanoes that result from quiet eruptions of basaltic lavas along divergent plate boundaries and oceanic hot spots
shield volcanoes
_____ travel slowly and rarely are deadly; they can last for many months or longer
Lava flows
_____ can explode out of a volcano up to 40 km into the air
Volcanic ash
_____ form when thermal energy from an erupting volcano melts snow. The meltwater can mix with _____ and _____ from the volcano and it flows downhill
mudflows
mud
ash
A(n) _______ is a fast-moving avalanche of hot gas, ash, and volcanic rock
pyroclastic flow
Volcanic eruption can be _______ by studying changes in the ground and patterns of earthquakes
predicted
_____, made up of tiny particles of pulverized volcanic rock and glass, erupts explosively
volcanic ash
The eruption style of a volcano depends on the amount of ______ dissolved in the magma, especially the amount of water vapor
gases
_____ is a fluid’s resistance to flow. Viscosity of lava is higher when the magma has a high ______ content
viscosity
silica
As magma rises toward Earth’s surface, the pressure on it ______. Bubbles of ____ form and rise in the magma. The bubbles affect the _____ of lava and the type of rock that forms as lava cools
decreases
gas
idk
The release of a large amount of volcanic ash can affect the Earth’s climate by blocking ______
sunlight
When droplets of sulfuric acid from volcanoes form in the atmosphere, they _____ sunlight into space
reflect
Volcanic ash and acid droplets in the atmosphere _____ Earth’s climate
affect
_____ are the vibrations in the ground that result from movement along breaks in Earth’s lithosphere
earthquakes
The forces that move _____ also push and pull rocks along breaks in the lithosphere
tectonic plates
Most earthquakes occur along active ____. These areas are generally in the middle of oceans or along the edges of ______.
plate boundaries
continents
Deep earthquakes occur along _____ plate boundaries, where a denser oceanic plate subducts into the mantle
convergent
Shallow earthquakes are common along _______ boundaries, where plates seperate
divergent
Earthquakes of varying depths occur where continents _____.
collide
Pressure applied to a rock can change the shape of the rock in a process called ______. This can eventually ______ the rock
rock deformation
A(n) ______ is a break in Earth’s lithosphere where one block of rock moves toward, away from, or past another block
fault
The three main kind of faults are ______, ______, and _______
strike-slip
normal
reverse faults
When rocks move in any direction along a fault, they release energy in Earth’s crust in _______
seismic waves
Seismic waves originate along the _____ where rocks first begin to move. This location inside Earth is the _______ of the earthquake
fault
focus
The _____ of an earthquake is the location on Earth’s surface directly above the focus
epicenter
The energy released during an earthquake is strongest near the ______
epicenter
An earthquake’s energy travel in three kinds of _____
seismic waves
_____(_____) cause particles in the ground to move in a push-pull motion similar to a coiled spring.
primary wave (P-waves)
_____ (_____) move rock particles side to side and up and down at right angles to the direction that the wave travels
Secondary waves (S-waves)
______ move the ground up and down and side to side in a rolling motion like an ocean wave.
Surface waves
Scientists who study earthquakes are called _______
seismologists
Seismic waves travel at different _______ and in different ______, depending on the materials they travel through.
speed
directions
S-waves cannot travel through liquids, including Earth’s ______
outer core
Seismic waves _______ as they travel through hot material. From this information, scientists model convection currents in Earth’s ______
change speed
mantle
A(n) ______ measures and records how much the ground moves and can be used to determine the distance seismic waves travel.
seismometer
A(n) _____ is a graphical illustration of seismic waves.
seismogram
The ______ uses the amount of motion at a given distance from an earthquake to determine the magnitude of the earthquake
Richter Scale
The _____ measures the amount of energy released by an earthquake
Moment Magnitude Scale
The ________ measures earthquake intensity based on descriptions of the earthquake’s effects on people and structures.
Modified Mercalli Scale
In the United States, most earthquakes occur near transform faults and _____
convergent plate boundaries
Seismologists assess ______ based on past earthquake activity, the geology around a fault, population density, and building design
risk
What do scientists use to find the epicenter?
triangulation
