[Q#3201] Open Google Earth. Check and double-click on the Mt. Helens Oblique View in the Lab 3 folder.

[Q#3201]

Open Google Earth. Check and double-click on the Mt. St. Helens Oblique View in the Lab 3 folder. Use the Look tool (circle with an eye in the middle, in the upper right corner) to rotate the view. either dragging the cursor around the outer ring or by clicking on the right and left arrows.

Fly around the mountain and observe the crater left by the eruption.

Which choice best describes the shape of the crater at the summit?

U-shaped and open toward the north

U-shaped and open toward the southwest

An elliptical or oval-shaped depression

Almost a perfectly circular depression

Question 2

1

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2. Question 2

[Q#3202]

Check and double-click Placemark 1 and Placemark 2. Then check the Mt. St. Helens Volcanic Features overlay. This illustrates the areas affected by different aspects of the eruption. Toggle the map on and off several times to compare it with the satellite view. Alternatively, you can make the overlay semi-transparent using the slider at the bottom of the Places panel.

Which items in the following list describe effects of the eruption? Select as many as apply.

Burnt zone

Lava flows

Debris flows

Mud flows

Pyroclastic flows

Volcanic bombs

Trees knocked down

Question 3

1

point

3. Question 3

[Q#3203]

Placemark 2 is located at the farthest point from the summit that felt direct effects from the eruption. Use the Ruler tool (located on the tool bar at the top of the map) to measure the distance between Placemarks 1 and 2.

24 km

22 km

26 km

28 km

Question 4

1

point

4. Question 4

[Q#3204]

Now turn off the Mt. St. Helens Volcanic Features map, and adjust your position and eye altitude so that you can see all of Mt. St. Helens and the surrounding river valleys. When hot ash and lava erupted through snow and ice, volcanic mudflows, or lahars, formed and these flooded river valleys around the mountain.

How many valleys still bear visible signs of the lahars at distances greater than ~10 km from Placemark 1 inside the crater?

0-2

6-8

9-11

3-5

Question 5

1

point

5. Question 5

[Q#3205]

Go to the Mount St. Helens Fact Sheet (PDF) and scroll down to the "Summary of May 18, 1980, Eruption" table.

What volume of material was removed from the mountain by the eruption? Hint: Make sure you pay attention to the units of your answer.

0.19 km3

2.79 km3

6.22 km3

0.67 km3

Question 6

1

point

6. Question 6

[Q#3206]

How big was the area affected by the initial explosion (called the lateral blast)? Hint: Make sure you pay attention to the units of your answer.

230 km2

596 km2

60 km2

23 km2

Question 7

1

point

7. Question 7

[Q#3207]

The Volcanic Explosivity Index was developed to compare the relative size of volcanic explosions. It rates eruptions on a scale from 0 to 7, with 7 indicating the most explosive.

What was the VEI of the 1980 eruption of Mt. St. Helens? You may need to search online to answer this question.

3

6

4

5

Question 8

1

point

8. Question 8

[Q#3208]

Go back to Google Earth and check and double-click on the link for the Mt. Vesuvius Oblique View. Use the Look tool to rotate the view. Fly around the mountain and observe its shape.

Which of the following choices best describes the summit area?

A large elliptical or oval-shaped crater

U-shaped and open toward the south

Small cone and crater inside an older crater

U-shaped and open toward the northeast

Question 9

1

point

9. Question 9

[Q#3209]

The present-day cone of Mt. Vesuvius stands within the remnants of a much larger depression known as a caldera. Prior to the eruption in the year 79, the summit caldera covered much of the forested area east of the modern cone. The eruption blasted away most of the caldera rim, so that less than half of it is visible today. The remaining caldera wall is similar in shape to the present-day crater of Mt. St. Helens, so geologists assume that Vesuvius too erupted with a lateral blast.

Toward which direction was this lateral blast directed (i.e., which way does the caldera open)?

Northwest

Southeast

Northeast

Southwest

Question 10

1

point

10. Question 10

[Q#3210]

Uncheck the oblique view. Then check the Mt. Vesuvius Volcanic Features overlay to see deposits left by several eruptions over thousands of years. Toggle the map on and off several times to compare it with the satellite view. Alternatively, you can make the overlay semi-transparent using the slider at the bottom of the Places panel.

Which items in the following list describe effects of the eruption? Select as many as apply.

Landslide deposits

Welded scorias

Mud flows

Pyroclastic flows and falls

Volcanic bombs

Debris flows

Lava flows

Question 11

1

point

11. Question 11

[Q#3211]

Check and double-click Placemark 3 and Placemark 4. Use the Ruler tool to measure between Placemarks 3 and 4 to find the distance (in km) from Mt. Vesuvius to the excavated ruins of Pompeii.

If a pyroclastic surge accompanies the next eruption of Mt. Vesuvius and it travels at 300 km/hr, how many minutes would it take to reach the site of ancient Pompeii?

~7 minutes

~15 minutes

~9 minutes

~2 minutes

Question 12

1

point

12. Question 12

[Q#3212]

Go to the web page for Vesuvius and scroll down to the section for the 79 AD (Pompeii Pumice) eruption.

What was the tephra fall deposit volume of the eruption in 79?"

6.2 km3

3.3 km3

2.5 km3

1.6 km3

Question 13

1

point

13. Question 13

[Q#3213]

What was the maximum height of the ash column?

29 km

33 km

15 km

9 km

Question 14

1

point

14. Question 14

[Q#3214]

Find the approximate Volcanic Explosivity Index of the 79 eruption of Mt. Vesuvius.

How does this compare with the VEI of the1980 eruption of Mt. St. Helens?

VEI of Vesuvius was smaller than VEI of St. Helens

VEI of Vesuvius was about the same as VEI of St. Helens

VEI of Vesuvius was larger than VEI of St. Helens

Question 15

1

point

15. Question 15

[Q#3215]

Go back to Google Earth and zoom to an eye altitude (indicated on the lower right corner of the map) of about 50 km (30 mi). In the Layers panel (bottom of the sidebar), open thePrimary Database > Borders and Labels folder > Labels folder, and check Populated Places. In the Places panel, check and double-click on the Vesuvius-St. Helens Comparison. You will see a circle centered on the summit of Mt. Vesuvius. The radius of the circle equals the distance you measured in question 3 for the farthest point that felt the direct effects of the 1980 Mt. St. Helens eruption.

The area inside the circle covers:

All of Naples but no other cities

All of Naples and many surrounding towns

Only part of the city of Naples

All of Naples and several nearby towns

Question 16

1

point

16. Question 16

[Q#3216]

Mt. St. Helens is located in a wilderness area, so its 1980 eruption killed fewer than 100 people. In contrast, approximately 4 million people live within the "Vesuvius-St. Helens Comparison" circle.

Given the risk they face, what actions would you expect inhabitants and elected officials of the Naples metropolitan area to take?

For this question, ignore the potential cost of any preparations. Select the single answer that describes the response you think would be the most effective thing elected officials could do. Note that more than one answer is possible, and indeed, there would be various ways to prepare for an eruption.

Fund scientific studies with the goal of predicting eruptions precisely (exact day and direction)

Prevent further development on the slopes of the mountain

Monitor the volcano closely for signs of activity

Fund scientific studies with the goal of preventing or stopping an eruption

Prepare for emergency medical care

Encourage people to move to a different city

Acquire construction equipment that can divert a lava flow or pyroclastic surge

Stockpile food and gasoline in case a catastrophic eruption blocks deliveries

Develop evacuation plans for communities closest to the volcano

Purchase guns and ammunition for self-defense if law and order break down

Stockpile water and batteries in case a catastrophic eruption cuts off utilities

Enforce building codes for strong structures with roofs that are fireproof