1. Which process could lead directly to the formation of ? A) precipitation of minerals from evaporating seawater B) metamorphism of unmelted rock material C) deposition of quartz sand D) of from a Base your answers to questions 2 through 4 on the map below. The black triangle represents Mt. , a volcano in . The isolines represent the thickness of ash, in centimeters, that settled on Earth's surface after a volcanic eruption of Mt. Hekla on March 29, 1947. Point X is a location on the surface of the ash.

2. At the time of the eruption, the wind direction was primarily from the A) east B) west C) north D) south 3. How many centimeters thick was the ash beneath point X? A) 0 B) 15 C) 20 D) 25 4. In addition to the ash, solid rock formed on Mt. Hekla from the lava extruded during this eruption. This rock is most likely A) light-colored metamorphic B) dark-colored metamorphic C) fine-grained igneous D) coarse-grained igneous

5. Base your answer to the following question on the map below, which shows an area of the northwestern United States affected by a major volcanic eruption at during the Holocene Epoch.

The pattern of distribution of the ash from the volcano was most likely caused by the direction of the A) magnetic field B) force of the volcanic eruption C) flow of surface D) atmospheric air movements 6. Base your answer to the following question on the cross section and map of a portion of Earth's crust shown below. The cross section and map show parts of the Pacific, Juan de Fuca, and North American tectonic plates, and Earth's interior. Letters A through F represent locations in the rock. The arrows indicate the general direction of plate movement relative to one another.

The Mount St. Helens volcano is composed mostly of rock. Therefore, the most common minerals at this location are A) potassium feldspar and quartz B) pyroxene and C) feldspar and hornblende D) biotite and quartz 7. An Earth science class is preparing a booklet on emergency preparedness. State one safety measure that should be taken to minimize danger from each of the following threats. a b Tornado c Volcanic eruption Base your answers to questions 8 through 13 on the reading passage and maps below. The enlarged map shows the location of volcanoes in Colombia, South America. Fire and Ice — and Sluggish

On the night of November 13, 1985, , a 16,200-foot (4,938 meter) snowcapped volcano in northwestern Colombia, erupted. Snow melted, sending a wall of mud and water raging through towns as far as 50 kilometers away, and killing 25,000 people. Long before disaster struck, Nevado del Ruiz was marked as a trouble spot. Like Mexico City, where an killed at least 7,000 people in October 1985, Nevado del Ruiz is located along the . This ring of islands and the coastal lands along the edge of the Pacific Ocean are prone to volcanic eruptions and crustal movements. The ring gets its turbulent characteristics from the motion of the tectonic plates under it. The perimeter of the Pacific, unlike that of the Atlantic, is located above active tectonic plates. Nevado del Ruiz happens to be located near the junction of four plate boundaries. In this area an enormous amount of heat is created, which melts the rock 100 to 200 kilometers below Earth's surface and creates magma. Nevado del Ruiz hadn't had a major eruption for 400 years before this tragedy. The reason: sluggish magma. Unlike the runny, magma that makes up the lava flows of oceanic volcanoes such as those in Hawaii, the magma at this type of subduction plate boundary tends to be sticky and slow moving, forming the rock andesite when it cools. This andesitic magma tends to plug up the opening of the volcano. It sits in a underground with pressure continually building up. Suddenly, tiny cracks develop in Earth's crust, causing the pressure to drop. This causes the steam and other gases dissolved in the magma to violently expand, blowing the magma plug free. Huge amounts of ash and debris are sent flying, creating what is called an explosive eruption. Oddly enough, the actual eruption of Nevado del Ruiz didn't cause most of the destruction. It was caused not by lava but by the towering walls of sliding mud created when large chunks of hot ash and pumice mixed with melted snow.

8. What are the names of the four tectonic plates located near the Nevado del Ruiz volcano? 9. What caused most of the destruction associated with the eruption of Nevado del Ruiz?

10. What caused the magma to expand, blowing the magma plug free?

11. is very common in igneous rocks formed during andesitic eruptions. Explain how this texture is formed.

12. Why are eruptions of Nevado del Ruiz generally more explosive than most Hawaiian volcanic eruptions?

13. Describe one emergency preparation that may reduce the loss of life from a future eruption of the Nevado del Ruiz volcano. Base your answers to questions 14 through 18 on the passage and the map below. The passage describes the New Madrid fault system. The numbers on the map show the predicted relative damage at various locations if a large earthquake occurs along the New Madrid fault system. The higher the number, the greater the relative damage. The New Madrid Fault System

The greatest earthquake risk area east of the Rocky Mountains is along the New Madrid fault system. The New Madrid fault system consists of a series of faults along a weak zone in the continental crust in the midwestern United States. occur in the Midwest less often than in , but when they do happen, the damage is spread over a wider area due to the underlying bedrock. In 1811 and 1812, the New Madrid fault system experienced three major earthquakes. Large land areas sank, new lakes formed, the course of the Mississippi River changed, and 150,000 acres of forests were destroyed.

14. On the map above, draw the 4, 6, and 8 isolines indicating relative damage.

15. Using the predicted damage numbers, place an X on the map to indicate where the New Madrid fault system most likely exists. 16. The distance between the New Madrid fault system and Albany, New York, is 1800 kilometers. What was the time difference between the arrival of the first P-wave and the arrival of the first S-wave at Albany when the 1812 earthquake occurred?

17. State one reason why earthquakes occur more frequently on the western coast of the United States than in the New Madrid region.

18. An emergency management specialist near the New Madrid region is developing a plan that would help save lives and prevent property damage in the event of an earthquake. Describe two actions that should be included in the plan.

19. Base your answer to the following question on the cross section below, which shows the paths of seismic waves traveling from an earthquake epicenter through the different layers of Earth's interior.

No P-waves or S-waves are received in the shadow zone because A) P-waves are absorbed and S-waves are refracted by Earth's outer core B) P-waves are refracted and S-waves are absorbed by Earth's outer core C) both the P-waves and S-waves are refracted by Earth's outer core D) both the P-waves and S-waves are absorbed by Earth's outer core 20. Earthquake S-waves do not travel through the 22. A seismograph station recorded the arrival of the Earth's first P-wave at 7:32 p.m. from an earthquake that occurred 4000 kilometers away. What time was it at A) crust B) moho the station when the earthquake occurred? C) mantle D) core A) 7:20 p.m. B) 7:25 p.m. 21. A P-wave takes 8 minutes and 20 seconds to travel from the epicenter of an earthquake to a seismic C) 7:32 p.m. D) 7:39 p.m. station. Approximately how long will an S-wave take to travel from the epicenter of the same earthquake to this seismic station? A) 6 mm 40 sec B) 9 mm 40 sec C) 15 mm 00 sec D) 19 mm 00 sec 23. The seismogram below shows the arrival times of P- 27. A huge undersea earthquake off the Alaskan and S-waves from a single earthquake. How far from coastline could produce a the earthquake epicenter was the station that A) B) cyclone recorded this seismogram? C) hurricane D) thunderstorm

A) 1.5 × 103 km B) 2.5 × 103 km C) 3.0 × 103 km D) 4.0 ×103 km 24. Which graph best represents the relationship between volcanic activity and earthquake activity in an area? A) B)

C) D)

25. The difference in arrival times for P- and S-waves from an earthquake is 5.0 minutes. How far away is the epicenter of the earthquake? A) 1.3 × 103 km B) 2.6 × 103 km C) 3.5 × 103 km D) 8.1 × 103 km 26. When the seafloor moves as a result of an underwater earthquake and a large tsunami develops, what will most likely occur? A) Deep-ocean sediments will be transported over great distances. B) No destruction will occur near the origin of the earthquake. C) The direction of the tsunami will be deter- mined by the magnitude of the earthquake. D) Severe destruction will occur in coastal areas. Base your answers to questions 28 through 31 on the map below and the cross sections on the next page. The map shows a portion of the Indian Ocean and surrounding landmasses. The location of the epicenter of a large undersea earthquake that occurred on December 26, 2004, is shown by an X. The isolines surrounding the epicenter show the approximate location of the first tsunami wave produced by this earthquake in half-hour intervals after the initial earthquake. Cross sections I and II illustrate how this undersea earthquake produced the tsunami. Cross section III shows the tsunami approaching a shoreline. The cross sections are not drawn to scale. 28. State the latitude and longitude of the epicenter of this earthquake. Include the units and compass directions in your answer.

29. According to the map, how long after this earthquake did the first tsunami wave arrive at Bengkulu, Sumatra?

30. Identify the overriding tectonic plate at the convergent plate boundary where this earthquake occurred.

31. Based on cross section III, describe the ocean water-level change at the shoreline that people observed just before the first tsunami wave approached the shore. Answer Key Topic 12 quiz #2

1. D 10. Examples: – a drop 13. Examples: – 17. Examples: — The 2. C in pressure on the Geologists should western coast of the magma – Steam and monitor conditions United States is near 3. B gases that were and provide early plate boundaries. — 4. C dissolved in the warning. – People More major faults magma violently should leave their are located on the 5. D expanded. – Cracks houses when early western coast of the 6. C in Earth's crust warning of an United States. — 7. a: Seek indoor lowered pressure on eruption is given. – Fewer active faults shelter – Avoid high the magma. – Avoid building are located in the ground – Stay in Magma pressure homes in valleys. – central portion of the your car cracked the People should be United States b: Go to the cellar or overlying rocks, discouraged from compared to the the safest interior releasing the gases. building near the western coast of the room – Stay away 11. Examples: – volcano. – United States. — from windows, Escaping gas Evacuation routes The central portion Open house bubbles are trapped should be of the United States windows in the rapidly publicized. – is in the middle of a c: Evacuate the area cooling magma. – Predicted mudslide tectonic plate. – Move away from Gas/air pockets form routes should be 18. Examples: — plan sites directly in the rock as it identified. evacuation routes — downhill from the cools. 14. identify earthquake volcano 12. Examples: – hazard zones or 8. 1. South American Hawaiian magma is areas that are subject Plate 2. Cocos Plate mafic and the to damage during an 3. Caribbean Plate 4. magma of the earthquake — plan Naza Plate Nevado del Ruiz emergency communication 9. Examples: mass volcano is andesitic. – Hawaiian magma procedures — movement of mud develop emergency down the mountain is runny and the 15. magma of Nevado information – a mud avalanche – brochures — store It melted snow, del Ruiz is thick and slow moving. – food, supplies, and causing mudslides. – fresh water — build Hot ash and pumice Hawaii is located at a hot spot in the earthquake-resistant melted snow, structures — identify creating landslides. center of the Pacific Plate. Nevado del shelter locations Ruiz is near a 19. B 16. 3 min 0 sec 10 subduction plate seconds 20. D boundary. 21. C 22. B 23. D 24. A 25. C 26. D Answer Key Topic 12 quiz #2

27. A 28. Latitude: 3.00 to 4.0° N. Longitude: 95.5 to 96.5° E. 29. any value from 1 hr 32 mm to 1 hr 42 mm. 30. Eurasian Plate. 31. The ocean water receded.