ESC, Exam 2

A magnitude 4 earthquake is ________ times as strong as a magnitude 2 earthquake

100

P-waves reaches a seismogram 4 minutes after an earthquake occurs and the S-waves arrive 3 and a half minutes later. How far is the seismogram from the earthquakes epicenter?

3000 km

An increase of 1 on the Richter scale is equivalent to an increase of ______ times the energy released and an increase of _____ times the "strength" of the earthquake

32, and 10

Where was the strongest earthquake? What was the year and magnitude?

Chile 1960 (in a subduction area), with a magnitude of 9.5

What causes an earthquake?

Earthquakes are usually caused when rock underground suddenly breaks along a fault. This sudden release of energy causes the seismic waves that make the ground shake. When two blocks of rock or two plates are rubbing against each other, they stick a little. They don't just slide smoothly; the rocks catch on each other. The rocks are still pushing against each other, but not moving. After a while, the rocks break because of all the pressure that's built up. When the rocks break, the earthquake occurs. During the earthquake and afterward, the plates or blocks of rock start moving, and they continue to move until they get stuck again. The spot underground where the rock breaks is called the focus of the earthquake. The place right above the focus (on top of the ground) is called the epicenter of the earthquake.

What are the three factors that cause the mantle to melt? Describe each one

Heating, Decompression, Addition of a flaux

What is true about the focus?

It is the point where the waves are originated

What are the three factors that cause the mantle to melt during sea floor spreading?

Melting, mantle is made up of different chemical components. The minerals that are enriched with silicone melts faster than the minerals that are enriched with iron. This creates magma. It melts by decompression things begin to tear apart Differentiation (in composition), the solid iron becomes liquid because the part that is enriched in silicone melts faster Extrusion, because the magma is now mafic rather then ultramafic, it is now less dense which allows it to expand and go through the vents to then come out an eruption

Relative speed (fastest - slowest) waves

P waves, S waves, Love waves, and Rayleigh waves

What are the 3 types of seismic waves that are generated by an earthquake?

P waves, S waves, and Surface waves

The three principal magma types are Andesite - Rhyolite - Basalt. List them in order from highest viscosity to lowest viscosity. Which is the most mafic? Which is the most sialic?

Rhyolite Andesite Basalt Basalt is the most mafic and Rhyolite is the most sialic

Describe how seismic waves images tell us Earth's core is liquid

S waves can't reach the inner core because the outer core is liquid. The S waves just bounce off the outer core and eventually shear out and disappear

Which wave types are body waves? Which wave types are surface waves?

The two types of body waves are P waves and S waves because they occur within the earth. The two types of surface waves are love wave and rayleigh waves

What is a stratovolcano? How many are there?

a stratovolcano is a tall, conical volcano composed of one layer of hardened lava, tephra, and volcanic ash. It has explosive and pyroclast eruptions. With high viscosity and sialic magma There are 700 associated with subduction and in the cascades

P waves

also known as primary waves (first one to reach), it is a sound wave practically. Particles move parallel. It is compressed. Like a slinky. Goes through solids, liquids, and gases.

Loves waves

are surface seismic waves that cause horizontal shifting of the Earth during an earthquake side to side and up and down (horizontal), like the motion of a whip

Where in the geosphere is magma generated?

asthenosphere

How many seismograms are needed to determine the location of an epicenter?

at least three

What is the difference between body waves and surface waves?

body waves are within the earth, surface waves are just right above

What type of eruption builds a shield volcano?

effusive eruptions, which are low viscosity

What are Pelee's tears and Pelee's hair? What kind of volcanic eruption produces them?

effusive type of eruptions, and it is volcanic glass

Describe the elastic rebound theory

elastic energy goes back to its original state. It is stored in plate boundaries. Then can be transformed into motion. The lithosphere has limited elastic energy. Once the energy is released it can go back to its original state. Elastic energy transforms into "sound"

If you know the time lag between the arrival of a P-wave and the arrival of the S-wave, you can use a seismogram graph to determine the distance to the ______________

epicenter (the closer the time lag, the closer the epicenter)

What is the difference between an explosive eruption and an effusive eruption? Which one produces tephra and which one produces lava?

explosive eruption means shooting outward intensely, this produces tephra. effusive eruptions produce lava and the eruption is much more flowy

What keeps the stable part of the seismometer from moving during an earthquake?

inertia inertia is the quality in matter (matter is anything you can touch) that lets it stay still if it is still, or keeps it moving if it is moving.

Focus

is the point within the earth where the earthquake slip begins

What type of volcano was Mt.Saint Helens? When was the last eruption?

it was a super volcano/stratovolcano and the last eruption was in 1980

What is partial melting? How does it lead to a magma that has a higher Si-content than the rock that melted to produce it?

mantle is made up of several minerals, it is made of many chemical components that have many melting properties. Minerals that are rich in silicone melts earlier. So the magma that comes out is mafic rather than ultramafic. What is left behind inside is solid because it is the minerals that is high in iron. Partial melting is part of differentiation (richment in silicone)

Magma issues out of vents in volcanoes and along fissures at _______________________

mid ocean ridges

S waves

only goes through solids, the particles move perpendicular to the direction of the wave like a wave at a baseball game

A city is located over an active fault, but has not experienced an earthquake for a long period of time. The city is most likely located where?

over a seismic gap

Pumice

pretty rock scrub, it is hardened lava rock used in construction work

What is a pyroclastic flow? What kind of volcanic eruption produces it?

pyroclastic flow is partially solidified magma that is thrown in the air to then come back down. This builds a new volcano from the top down. The parts that are less denser go farther down and farther from the volcano. The explosive eruptions is what produces it

A ____ fault forms as a result of horizontal compression.

reverse

Sea Floor Spreading

seafloor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge. (Subduction) Seafloor spreading helps explain continental drift in the theory of plate tectonics.

Earthquake

shaking of the earth caused by sudden motions along fractures in the earth's crust called faults

The strain which causes a material to twist is known as ____

shear, the ground motion and therefore shear strain is at a maximum during the earthquake like an indian burn?

Label each as having a gentle slope or a steep slope. Which one builds up through eruptions of low-viscosity magma? Which is typically found in volcanic arcs?

shield volcanoes have gentle slopes, stratovolcanoes have steep slopes. The shield volcanoes have low viscosity magma (runny magma)

Where do Shield volcanoes and Stratovolcanoes "originate"? How does this affect the eruptions?

shield volcanoes under oceanic crust and stratovolcanoes under continental crust. The volcanoes that are under thick continental crust, have a lot of trapped gas. It's much harder for that gas to be released therefore there's a lot of gas pressure and the explosive eruptions are crazy

Magma viscosity is a function of the relative abundance of ________

silicone

Rayleigh waves

slowest waves,

What is the state of matter of mantle and its composition?

solid and it is ultramafic contains O-SI (silicone), Aluminum, Magnesium, and Iron

Give an example of a shield volcano and a stratovolcano in the USA. In which mountain belt are the stratovolcanoes located?

stratovolcano: cascade and andes, Shield volcanoes hawaii

The strain which causes a material to pull apart is known as

tension

Ash, lapilli, and volcanic bombs are names given to different sizes of _____

tephra

What type of volcano is yellowstone park?

the Yellowstone Caldera is a volcanic caldera and supervolcano located in Yellowstone National Park in the United States, sometimes referred to as the Yellowstone Supervolcano

What is the difference between the focus point and epicenter of an earthquake?

the focus is the point within the earth where seismic waves originate; it is centered on the part of the fault that has the greatest movement. The epicenter is on the earth's surface directly above the focus

What is the difference between where an earthquake "occurs" and where it "originates"?

the focus point is where the earthquake originates, where an earthquake occurs is the epicenter

Magnitude

the magnitude is a number that characterizes the relative size of an earthquake. Magnitude is based on measurement of the maximum motion recorded by a seismograph.

Which part of the seismometer does not shake during an earthquake?

the pendulum and pen

Seismology

the study of ground motions

On a seismometer, vibrations of the ground do not move the ____.

the suspended mass

What is the relation between fault plane, focus and epicenter?

the three things to look at to determine the location of an earthquake is the fault plane, focus and epicenter. The epicenter represents the surface point. It is a point on land above the focus point where the earthquake began. The fault plane says a lot about the focus point. Based off the way the fault plane is created, whether it is horizontal or vertical determines the way the fault was made.

Calderas Volcanoes

the vent is close to the magma chamber, huge bump with huge gas pressures. It is a collapsed structure and sometimes collapses on itself. It empxties out its magma chambers

What is the difference between the Mercalli intensity scale and the Richter magnitude scale?

this energy is measured by how much "shaking" occurs. The shaking can vary in its intensity. The Richter Scale is an absolute scale; wherever an earthquake is recorded, it will measure the same on the Richter Scale. Second, the Modified Mercalli scales measures how people feel and react to the shaking of an earthquake. It is subjective.

What is a seismic gap?

time without any earthquake along certain segment, likelihood of earthquake increases with time. The longer the time, the greater the magnitude expected. The longer the time the more energy is going to be released

If you know the time lag between the arrival of a P-wave and the arrival of the S-wave, you can use a ___________ graph to determine the distance to the ______________

time, and epicenter

Seismometers

tools to measure the waves of earthquakes

Seismic waves are best described as :

vibrations

What are the most common volcanic gases?

water vapor (H2O), carbon dioxide (CO2), and sulfur dioxide (SO2)

What is a wave?

waves is transporting particles from one place to another. But the particles do not "move" they are being pushed. It is the energy that moves, the energy is going through the atoms thus creating that movement

Seismic Waves

waves that transmit the energy released by an earthquake