2005 Submarine Ring of Fire Expedition It’s Going to Blow Up! FOCUS TEACHING TIME Volcanism on the Pacific Ring of Fire One or two 45-minute class periods, plus time for student research GRADE LEVEL 7-8 (Earth Science) SEATING ARRANGEMENT Classroom style if students are working individually, FOCUS QUESTION or groups of two to four students What are major characteristics of volcanoes on the Pacific Ring of Fire? MAXIMUM NUMBER OF STUDENTS 30 LEARNING OBJECTIVES Students will be able to describe the processes that KEY WORDS produce the “Submarine Ring of Fire.” Volcano Caldera Students will be able to explain the factors that Cascade Mountains contribute to explosive volcanic eruptions. Ring of Fire Asthenosphere Students will be able to identify at least three ben- Lithosphere efits that humans derive from volcanism. Magma Fault Students will be able to describe the primary risks Transform boundary posed by volcanic activity in the United States, and Convergent boundary will be able to identify the volcano within the conti- Divergent boundary nental U.S. that is considered most dangerous. Subduction Tectonic plate MATERIALS Copies of “Ring of Fire Volcanism Worksheet,” BACKGROUND INFORMATION one copy for each student or student group The Ring of Fire is an arc of active volcanoes and earthquake sites that partially encircles the Pacific AUDIO/VISUAL MATERIALS Ocean Basin. The location of the Ring of Fire coin- (Optional) Equipment for viewing video clips from cides with the location of oceanic trenches and the Ocean Explorer Web site volcanic island arcs that result from the motion of large pieces of the Earth’s crust (tectonic plates). Tectonic plates consist of portions of the Earth’s outer crust (the lithosphere) about 5 km thick, as 1 2005 Submarine Ring of Fire Expedition – Grades 7-8 (Earth Science) 2005 Submarine Ring of Fire Expedition – Grades 7-8 (Earth Science) Focus: Volcanism on the Pacific Ring of Fire oceanexplorer.noaa.gov oceanexplorer.noaa.gov Focus: Volcanism on the Pacific Ring of Fire well as the upper 60 - 75 km of the underlying boundaries. The Ring of Fire marks the location of mantle. The plates move on a hot flowing mantle a series of convergent plate boundaries in the west- layer called the asthenosphere, which is several ern Pacific Ocean. hundred kilometers thick. Heat within the astheno- sphere creates convection currents (similar to the The Mariana Arc is part of the Ring of Fire that currents that can be seen if food coloring is added lies to the north of Guam in the western Pacific. to a heated container of water). These convection Here, the fast-moving Pacific Plate is subducted currents cause the tectonic plates to move several beneath the slower-moving Philippine Plate, cre- centimeters per year relative to each other. ating the Marianas Trench (which includes the Challenger Deep, the deepest known area of the The junction of two tectonic plates is known as Earth’s oceans). The Marianas Islands are the result a plate boundary. Where two plates slide hori- of volcanoes caused by this subduction, which zontally past each other, the junction is known frequently causes earthquakes as well. In 2003, as a transform plate boundary. Movement of the the Ocean Exploration Ring of Fire expedition sur- plates causes huge stresses that break portions of veyed more than 50 volcanoes along the Mariana the rock and produce earthquakes. Places where Arc, and discovered that ten of these had active these breaks occur are called faults. A well-known hydrothermal systems (visit http://oceanexplorer.noaa.gov/ example of a transform plate boundary is the San explorations/03fire/welcome.html for more information Andreas fault in California. on these discoveries). The 2004 Submarine Ring of Fire Expedition focussed specifically on hydro- Where tectonic plates are moving apart, they form thermal systems of the Mariana Arc volcanoes, a divergent plate boundary. At these boundar- and found that these systems are very different ies, magma (molten rock) rises from deep within from those found along mid-ocean ridges (visit http: the Earth and erupts to form new crust on the //oceanexplorer.noaa.gov/explorations/04fire/welcome.html for lithosphere. Most divergent plate boundaries are more information). The 2005 Submarine Ring of underwater (Iceland is an exception), and form Fire Expedition will explore hydrothermally active submarine mountain ranges called oceanic spread- volcanoes in the Kermadec Arc, an area where tec- ing ridges. tonic plates are converging more rapidly than any other subduction zone in the world. If two tectonic plates collide more or less head-on, they produce a convergent plate boundary. Usually, On April 1, 2004, scientists exploring the NW one of the converging plates moves beneath the Rota #1 volcano reported the first-ever direct other in a process called subduction. Subduction observations of a submarine volcanic eruption. In produces deep trenches, and earthquakes are com- this lesson, students will investigate some character- mon. As the sinking plate moves deeper into the istics of volcanoes associated with the Submarine mantle, increasing pressure and heat release fluids Ring of Fire, including volcanoes present within the from the rock causing the overlying mantle to par- continental United States. tially melt. The new magma rises and may erupt violently to form volcanoes that often form arcs LEARNING PROCEDURE of islands along the convergent boundary. These 1. To prepare for this lesson, read island arcs are always landward of the neighbor- • the background article on “Arc Volcanism” ing trenches. This process can be visualized as a (http://oceanexplorer.noaa.gov/explorations/05fire/ huge conveyor belt on which new crust is formed background/volcanism/volcanism.htm); and at the oceanic spreading ridges and older crust is • Submarine Ring of Fire 2004 daily logs for recycled to the lower mantle at the convergent plate April 1 and April 4 (http://oceanexplorer.noaa.gov/ 2 3 2005 Submarine Ring of Fire Expedition – Grades 7-8 (Earth Science) 2005 Submarine Ring of Fire Expedition – Grades 7-8 (Earth Science) Focus: Volcanism on the Pacific Ring of Fire oceanexplorer.noaa.gov oceanexplorer.noaa.gov Focus: Volcanism on the Pacific Ring of Fire explorations/04fire/logs/april01/april01.html; and http: Silica molecules make magmas very viscous, //oceanexplorer.noaa.gov/explorations/04fire/logs/april04/ and the high viscosity traps gasses, producing april04.html). pressures that result in explosive eruptions. You may also want to visit the US Geological 3. What is a caldera? Survey’s Cascades Volcano Observatory Web a huge depression at the top of a volcano site (http://vulcan.wr.usgs.gov/) to become familiar with formed by explosive eruptions that remove the resources available. large volumes of magma from beneath a vol- cano, causing the ground to collapse into the 2. Briefly review the concepts of plate tectonics and emptied space continental drift and how they are related to underwater volcanic activity. You may want to 4. What volcanos in the Kermadec Arc are use resources from NOAA’s hydrothermal vent scheduled for exploration by the Submarine Web site (http://www.pmel.noaa.gov/vents/home.html) and Ring of Fire 2005 expedition? possibly the video clips linked to the Submarine Macauley, Brothers, Monowai, W, Healy, Ring of Fire 2004 daily log for April 1 and the Rumble-III, Rumble-V, Tangaroa, Clark Submarine Ring of Fire 2005 background page on the Kermadec Arc (http://oceanexplorer.noaa.gov/ 5. Why were these volcanoes selected for explo- explorations/05fire/background/kermadecarc/kermadecarc.html) ration? to supplement this discussion. Introduce the Ring because they show evidence of having active of Fire, and describe the processes that produce hydrothermal systems the island arcs. 6. Which of these volcanoes have conspicuous 3. Tell students that their assignment is to familiar- calderas? ize themselves with some basic concepts of Macauley, Brothers, Monowai, W, and Healy volcanology and to investigate a portion of the Ring of Fire that is present within the continental 7. What is mafic lava? United States. Provide each student or student lava having high concentrations of magne- group with a copy of “Ring of Fire Volcanism sium and iron Worksheet,” and direct students to research the answers to questions on the worksheet. You may 8. What mountain chain in the western United also want to provide formulas for the volume of a States is part of the Pacific Ring of Fire? cone and volume of a sphere, or may let students the Cascades find these on their own. 9. How much of the Earth’s surface, including the 4. Lead a discussion of students’ answers to work- ocean floor, is volcanic? sheet questions. The correct answers are: more than 80 percent of the Earth’s surface is of volcanic origin 1. What two features are associated with the most violent volcanic eruptions? 10. What are some benefits that result from vol- felsic magmas and the formation of big cal- canoes? deras volcanic ash increases soil fertility by adding nutrients; groundwater heated by hot magma 2. Why are magmas with high silica content can be used for geothermal energy; volcanic dangerous? processes concentrate valuable minerals into 2 3 2005 Submarine Ring of Fire Expedition – Grades 7-8 (Earth Science) 2005 Submarine Ring of Fire Expedition – Grades 7-8 (Earth Science) Focus: Volcanism on the Pacific Ring of Fire oceanexplorer.noaa.gov oceanexplorer.noaa.gov Focus: Volcanism on the Pacific Ring of Fire deposits that include most of the metallic min- 18. How much of the Mount St. Helens cone was erals mined in the world blown away during the May 18, 1980 erup- tion? 11. What was the most destructive volcanic erup- The volcano lost an estimated 3.4 billion cubic tion in the history of the United States? yards (0.63 cubic mile) of its cone.