Lab Power Point For Plp Analysis Of Magma Viscosity

LAB: LAB: *MAGMA *MAGMA VISCOSITY*VISCOSITY*

OVERVIEWOVERVIEW

Lava is molten rock that has been ejected onto the surface Lava is molten rock that has been ejected onto the surface by a volcano. Magma is molten rock that exists below by a volcano. Magma is molten rock that exists below the earth’s surface. Magma comes in many varieties:the earth’s surface. Magma comes in many varieties:

*It can range from thin and runny to thick and oozy.*It can range from thin and runny to thick and oozy.

*It can have a range of temperatures from low (cool) to *It can have a range of temperatures from low (cool) to

high (searing hot).high (searing hot).

*It can range from low gas content to high gas content.*It can range from low gas content to high gas content.

*It can range from a low silica content to a high silica *It can range from a low silica content to a high silica

content.content.

The type of magma plays a big part in the type of eruption The type of magma plays a big part in the type of eruption a volcano may produce. In turn, the eruption of lava a volcano may produce. In turn, the eruption of lava plays a major role in the formation of volcanoes, as plays a major role in the formation of volcanoes, as material accumulates and forms thick layers and piles material accumulates and forms thick layers and piles onon the surface of the cone. the surface of the cone.

If the lava is runny, it will flow downhill easily and spread out to If the lava is runny, it will flow downhill easily and spread out to form a shield volcano. If it is thick, chunky, and oozy, the lava form a shield volcano. If it is thick, chunky, and oozy, the lava will not move downhill very fast and may cool and solidify will not move downhill very fast and may cool and solidify before reaching the bottom. This builds a steeper volcano, before reaching the bottom. This builds a steeper volcano, possibly a cinder cone or even a composite volcano.possibly a cinder cone or even a composite volcano.

SHIELD SHIELD VOLCANOVOLCANO

CINDER CONE CINDER CONE VOLCANOVOLCANO

COMPOSITE VOLCANOCOMPOSITE VOLCANO

VISCOSITYVISCOSITY

Viscosity is the resistance of a liquid material to flow. In other Viscosity is the resistance of a liquid material to flow. In other words, it refers to how easily a fluid can move when subjected words, it refers to how easily a fluid can move when subjected to gravity. The ability to flow hinges on the consistency of to gravity. The ability to flow hinges on the consistency of the lava - how thin or how thick it is.the lava - how thin or how thick it is.

*Low viscosity causes the lava to be thin and runny.*Low viscosity causes the lava to be thin and runny.

*High viscosity causes the lava to be thick and oozy.*High viscosity causes the lava to be thick and oozy.

Temperature plays a part in this as well.Temperature plays a part in this as well.*Low temperatures cause lava to thicken and become more *Low temperatures cause lava to thicken and become more

viscous.viscous.*High temperatures cause lava to stay thin or less viscous.*High temperatures cause lava to stay thin or less viscous.

The amount of gases contained in magma will also affect its nature.The amount of gases contained in magma will also affect its nature. *Low gas content allows the particles to stay condensed, making *Low gas content allows the particles to stay condensed, making the the

magma thick.magma thick.*High gas content spreads out the particles and makes the *High gas content spreads out the particles and makes the magma thin.magma thin.

Gas pressure within the volcano’s vent will be affected by the Gas pressure within the volcano’s vent will be affected by the thickness of the magma:thickness of the magma:*If the magma is thin, gas pressure can bleed off easily, and there *If the magma is thin, gas pressure can bleed off easily, and there will will

be a quiet eruption.be a quiet eruption.*If the magma is thick, gas pressure builds due to the magma *If the magma is thick, gas pressure builds due to the magma becoming becoming

clogged in the vent. This causes a violent eruption.clogged in the vent. This causes a violent eruption.

The viscosity of the lava depends mostly The viscosity of the lava depends mostly on the silica content, which is the on the silica content, which is the amount of silica in magma or lava.amount of silica in magma or lava.

*Low silica content causes low viscosity.*Low silica content causes low viscosity.

*High silica content causes high *High silica content causes high viscosity.viscosity.

Magma can be of three types:Magma can be of three types:

*basaltic – has a low level of silica.*basaltic – has a low level of silica.

*granitic – has a medium level of silica.*granitic – has a medium level of silica.

*andesitic – has a high level of silica.*andesitic – has a high level of silica.

Purpose of this lab:Purpose of this lab:

The purpose of this lab is to The purpose of this lab is to initiate and observe three initiate and observe three scale model volcanic eruptions scale model volcanic eruptions in order to analyze the in order to analyze the viscosity of magma. The three viscosity of magma. The three samples of synthetic “magma” samples of synthetic “magma” have different levels of “silica” have different levels of “silica” present. Students will present. Students will determine magma viscosity , determine magma viscosity , and compare and contrast the and compare and contrast the three eruptions.three eruptions.

Materials needed:Materials needed:There are supplies needed for use by the teacher.There are supplies needed for use by the teacher.

*Refer to the attached video clip. (click below)*Refer to the attached video clip. (click below)

Other materials needed:Other materials needed:There are supplies that the students will There are supplies that the students will

need for their groups.need for their groups.

*Refer to the attached video clip. (click *Refer to the attached video clip. (click below)below)

PROCEDURES:PROCEDURES:PHASE 1 -– Build the volcano model:PHASE 1 -– Build the volcano model:


The distance between the start line and the finish The distance between the start line and the finish line on the volcano cone model is actually line on the volcano cone model is actually 7.8 cm7.8 cm..

PHASE 2 - Set up data table:PHASE 2 - Set up data table:

SAMPLE #SAMPLE # DISTANCE (CM) DISTANCE (CM) TIME (S) VELOCITY (CM/S) VISCOSITY (L, TIME (S) VELOCITY (CM/S) VISCOSITY (L, M, H)M, H)

11 7.8 7.8 ____

22 7.8 7.8 ____

33 7.8 7.8 ____

PHASE 3 - Fill the test tubes:PHASE 3 - Fill the test tubes:


PHASE 4 - Fill the dixie cups:PHASE 4 - Fill the dixie cups:


PHASE 5 - Trigger and measure the PHASE 5 - Trigger and measure the eruptions:eruptions:

TRIAL #1 (magma sample #1)TRIAL #1 (magma sample #1)


Log data for Trial #1 (magma sample Log data for Trial #1 (magma sample #1):#1):

SAMPLE #SAMPLE # DISTANCE (CM) DISTANCE (CM) TIME (S) VELOCITY (CM/S) VISCOSITY (L, M, TIME (S) VELOCITY (CM/S) VISCOSITY (L, M, H)H)

11 7.8 7.8 181.71 181.71 ____

22 7.8 7.8 ____

33 7.8 7.8 ____




SAMPLE #SAMPLE # DISTANCE (CM) DISTANCE (CM) TIME (S) VELOCITY (CM/S) VISCOSITY (L, M, H) TIME (S) VELOCITY (CM/S) VISCOSITY (L, M, H)

11 7.8 7.8 181.71 181.71 ____

22 7.8 7.8 52.12 52.12 ____

33 7.8 7.8 ____




SAMPLE #SAMPLE # DISTANCE (CM) DISTANCE (CM) TIME (S) VELOCITY (CM/S) VISCOSITY (L, M, H) TIME (S) VELOCITY (CM/S) VISCOSITY (L, M, H)

11 7.8 7.8 181.71 181.71 ____

22 7.8 7.8 52.12 52.12 ____

33 7.8 7.8 4.10 4.10 ____

Figure the velocity of each magma flow:

Trial #1: v = d / tv = 7.8 cm / 181.71 sv = .0429255 cm/s

Trial #2: v = d / tv = 7.8 cm / 52.12 sv = .1496546 cm/s

Trial #3: v = d / tv = 7.8 cm / 4.10 sv = 1.902439 cm/s

**To figure the velocity of the magma flow, use the formula:To figure the velocity of the magma flow, use the formula: v = d / t v = d / t(velocity = distance / time)(velocity = distance / time)

Log the velocity for each magma sample:Log the velocity for each magma sample:


11 7.8 7.8 181.71 .0429255181.71 .0429255 ____

22 7.8 7.8 52.12 .1496546 52.12 .1496546 ____

33 7.8 7.8 4.10 1.902439 4.10 1.902439 ____

Determine whether each magma sample Determine whether each magma sample had a low, medium, or high viscosity and had a low, medium, or high viscosity and log each one:log each one:


11 7.8 7.8 181.71 .0429255181.71 .0429255 HIGHHIGH

____

22 7.8 7.8 52.12 .1496546 52.12 .1496546 MEDIUMMEDIUM

33 7.8 7.8 4.10 1.902439 4.10 1.902439 LOWLOW____

CONCLUSION Part 1:CONCLUSION Part 1:

*Magma sample #1 in Trial #1 was *Magma sample #1 in Trial #1 was determined to be of high viscosity determined to be of high viscosity because it had the slowest flow rate because it had the slowest flow rate (velocity). Therefore, it could have (velocity). Therefore, it could have contained the highest amount of contained the highest amount of silica (possibly basaltic in nature). silica (possibly basaltic in nature). Also, it could possibly have a low gas Also, it could possibly have a low gas content, and may have been a cooler content, and may have been a cooler temperature than the other two temperature than the other two samples.samples.


*Magma sample #2 in Trial #2 was *Magma sample #2 in Trial #2 was determined to be of medium viscosity determined to be of medium viscosity because it had a flow rate (velocity) because it had a flow rate (velocity) that fell between the other two that fell between the other two samples. Therefore, it could have samples. Therefore, it could have contained a medium amount of silica contained a medium amount of silica (possibly granitic in nature). Also, it (possibly granitic in nature). Also, it could possibly have a medium gas could possibly have a medium gas content, and may have been a medium content, and may have been a medium temperature, falling somewhere temperature, falling somewhere between the other two samples.between the other two samples.


*Magma sample #3 in Trial #3 was *Magma sample #3 in Trial #3 was determined to be of low viscosity determined to be of low viscosity because it had the fastest flow rate because it had the fastest flow rate (velocity). Therefore, it could have (velocity). Therefore, it could have contained the lowest amount of contained the lowest amount of silica (possibly andesitic in nature). silica (possibly andesitic in nature). Also, it could possibly have a high Also, it could possibly have a high gas content, and may have been a gas content, and may have been a hotter temperature than the other hotter temperature than the other two samples.two samples.


The students’ times will vary from The students’ times will vary from group to group. They must be sure to group to group. They must be sure to start and stop timing as precisely as start and stop timing as precisely as possible. The variance in times will possible. The variance in times will also vary the magma velocities. Be also vary the magma velocities. Be prepared to have different answers for prepared to have different answers for different groups. Although, the different groups. Although, the sequence of viscosities is actually sequence of viscosities is actually “high - medium - low”. If the students “high - medium - low”. If the students have them listed in a different order, have them listed in a different order, then an error occurred somewhere.then an error occurred somewhere.

Analysis Questions:Analysis Questions:

1. What is viscosity?1. What is viscosity?

2. What factors can affect magma / lava 2. What factors can affect magma / lava viscosity?viscosity?

3. How is viscosity related to the shape 3. How is viscosity related to the shape and height of a volcano?and height of a volcano?

4. How might gas pressure within the 4. How might gas pressure within the volcano, coupled with magma volcano, coupled with magma viscosity, affect the type of eruption viscosity, affect the type of eruption that a volcano may produce?that a volcano may produce?

Answers:Answers:

1. Viscosity is the resistance of a material to flow. It 1. Viscosity is the resistance of a material to flow. It hinges on the consistency (thickness) of the hinges on the consistency (thickness) of the material.material.

2. Factors that can affect the viscosity of magma / lava 2. Factors that can affect the viscosity of magma / lava may include thickness (density), temperature, gas may include thickness (density), temperature, gas content, and silica content.content, and silica content.

3. If lava has a high viscosity, it is thick. Therefore, it will 3. If lava has a high viscosity, it is thick. Therefore, it will tend to flow short distances and will stay at or near tend to flow short distances and will stay at or near the top of the volcano. This builds tall, cylindrical the top of the volcano. This builds tall, cylindrical cones (cinder cone and composite volcanoes). cones (cinder cone and composite volcanoes). However, if the lava has a low viscosity, it is thin and However, if the lava has a low viscosity, it is thin and runny. It will flow long distances and will build a runny. It will flow long distances and will build a cone that is wide at the base (shield volcano).cone that is wide at the base (shield volcano).

4. High viscosity magma tends to clog the volcano’s vent, 4. High viscosity magma tends to clog the volcano’s vent, building gas pressure, and causing a violent building gas pressure, and causing a violent eruption. Low viscosity magma does not clog and eruption. Low viscosity magma does not clog and allows gas to escape, allowing for a quiet eruption.allows gas to escape, allowing for a quiet eruption.

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Lab Power Point For Plp Analysis Of Magma Viscosity