Unit 4 Risk at Divergent Plate Boundaries

This unit supports the following overarching goals:

1. Use qualitative and quantitative information to assess risk due to geologic hazards associated with plate boundaries.
2. Develop strategies to mitigate risk due to geologic hazards.

Unit 4 Learning Objectives (and areas in the unit where objectives are addressed)

1. Students will be able to describe several methods geologists use to monitor geologic activity associated with volcanic eruptions (prework).
2. Students will be able to interpret authentic GPS and earthquake data that indicate magma movement and ground deformation before, during and after volcanic activity (classwork, group work).
3. Students will be able to discuss factors that determine whether volcano monitoring can be effective in mitigating risk to people and property (classwork, wrap-up).

Students are expected to come to the activity with the following background:

• Familiarity with the basic tenets of plate tectonics and the general characteristics of plate boundaries. One suggested activity is Using Google Earth to Explore Plate Tectonics, by Laurel Goodell.

Unit 4 is designed for a 50-minute class period with an associated prework assignment, and it involves group work that can be adapted for most class sizes.

Unit 4 is designed for introductory-level geology courses, including courses in physical geology and geologic hazards, but is also appropriate for any course studying plate tectonics. The previous unit (3) establishes volcanism as a primary geologic hazard at subaerial divergent plate boundaries. Unlike the case for earthquakes (Units 1 and 2), there are a number of relatively reliable warning signs that can be used in combination to indicate a volcano is entering an eruptive phase. This unit introduces students to the role that volcano monitoring can play in giving timely warning about volcanic eruptions and thus mitigate risk to people and property.

After learning the basics of several methods (monitoring seismicity, ground deformation and gas emissions), students look in detail at earthquake activity and GPS times series data from before, during and after the 2010 eruption of the Icelandic volcano Eyjafjallajokull. This takes the form of a worksheet and associated PowerPoint presentation that the instructor uses to present the chronological events and data associated with the eruption. The presentation has a number of built-in steps in which students make predictions, analyze data and make interpretations about the volcanic activity, before continuing to see how their interpretations compare to actual events. Students are introduced to the use of data characteristic of an imminent eruption, and discover the time frame of pre-cursor activity. Students work in small groups (working on a particular GPS station, for example) before combining their results with those of the rest of the class.

Optional activity for a longer class or post-unit homework assignment: After "living through" and debriefing the events at Eyjafjallajokull, students are reminded of similar activity and the distinct effects of the 2003 eruption of Nyiragongo, in the Democratic Republic of the Congo. This volcano is in a similar tectonic setting as Eyjafjallajokull, but it resulted in significantly greater loss of life and property damage. Students compare events and monitoring activities at the two volcanoes, and identify factors that determine the effectiveness of volcanic monitoring in mitigation of risk.

Prework assignment

(15 min) Students are introduced to volcano monitoring as a way to reduce the vulnerability of people and property to volcanic eruptions, and thereby reduce the risk. Students do this by filling out a worksheet using information available from the online IRIS resources listed below. The information focuses on three types of data used to monitor volcanoes: seismicity, gas emission, and ground deformation. For each type of data, students review what equipment is needed, what is measured, and what are indicators of imminent eruption.

Then, to prepare for the classroom activity focused on the 2010 eruption of the Icelandic volcano Eyjafjallajokull, students view two short YouTube videos: one of NBC coverage of the 2010 eruption, and another with conversation between two volcanologists on how to pronounce the name of the volcano.

Prework files:

• Unit 4 prework student handout (Microsoft Word 2007 (.docx) 31kB Aug15 24) or the pdf version (Acrobat (PDF) 88kB Aug15 24)
• Overview of volcano monitoring techniques
• Animations of volcano monitoring techniques.  These can be accessed via the NSF SAGE (Seismological Facility for the Advancement of Geoscience) website under Volcanoes/Monitoring and are also posted at the YouTube links below:
  • Measuring Magmatic Gas
  • Volcanic Earthquakes
  • Measuring Deformation with Tiltmeters and GPS
  • Measuring Deformation with InSAR 
• Footage of Eyjafjallajokull eruption and tutorial on Icelandic pronunciation
  • NBC news coverage of eruption and travel disruption
  • Icelandic volcanolgist Dr. Þorbjörg Ágústsdóttir teaching New Zealand volcanologist Dr. Janine Krippner how to pronounce "Eyjafjallojokull."

For instructors only:

• Unit 4 prework instructor's key, MSWord -- private instructor-only file
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Classwork

1. Introduction (5 min)
   As an icebreaker, the class (and the instructor!) can practice pronouncing "Eyjafjallajokull" (see prework). The instructor reviews the homework assignment and emphasizes the feasibility of and importance of monitoring volcanoes in order to mitigate risk from volcanic eruptions. Iceland frequently has to deal with volcanic eruptions and has an extensive monitoring system in place; the 2010 eruption is a fascinating case study.
2. Ground deformation and seismicity associated with the 2010 Eruption of Eyjafjallajokull (35 min)
   In this section, students do a detailed analysis and interpretation of GPS and earthquake data that document events before, during and after the 2010 eruption of Eyjafjallajokull—from the dormancy period (no ground deformation, few earthquakes), precursor activity (inflation, increasing # of earthquakes with this activity accelerating just prior to eruption), eruption (stabilization of ground deformation, lower seismicity), and return to dormancy (deflation with some permanent deformation, low seismicity). 
   
   Note that this classwork activity only includes two types of volcanic monitoring data (volcanic seismicity and ground deformation measured by GPS).  Other techniques that are explored in the prework assignment (gas emission, ground deformation measured by tiltmeters and InSAR) are not included.
   
   The instructor uses the provided PowerPoint both as a guide and as a supplement for students as they complete their worksheets. There is opportunity for the small groups to discuss results among themselves, and then report their results to the class so that the class has all the data. The exercise progresses as follows:
   • Students do a thought experiment to predict and interpret what intrusion of magma and subsequent eruption would do the external shape of a volcano.
   • Students learn about the 2010 eruption of Eyjafjallajokull, viewing images from the eruption and getting information about damage and casualties.
   • Students review how to read GPS time series.
   • Students analyze and interpret the time series for one of four GPS stations from dormancy, through the precursor activity, through the eruption, and finally back into dormancy.
   • Students report data from all four stations and collaborate to give a broader view of what is going on at the volcano.
   • Students analyze a graph showing cumulative number of earthquakes for the same time period covered by the GPS data, and relate the earthquake data to the GPS data.

• a copy of the class handout
• the GPS time series for one of four GPS stations.

1. Discussion Questions (10 min)
   Students are asked to respond the following wrap-up questions, which also serve as formative assessment for the learning objectives of this unit (see Assessment). This could be done as a class discussion, small group work, or individually. These questions are included in a slide at the end of the PowerPoint presentation, and also on the last page of the class handout. Numbers on the questions below correspond to the numbers on the class handout.

Classwork activity files:

• Unit 4 PowerPoint for classroom activity (PowerPoint 2007 (.pptx) 12.1MB Aug15 24) or this pdf version (Acrobat (PDF) 5.9MB Aug15 24)
• Unit 4 activity student handout for Eyjafjallajokull eruption work, MSWord (Microsoft Word 2007 (.docx) 2.3MB Apr8 15) or the PDF version (Acrobat (PDF) 1MB Apr8 15)
• Unit 4 GPS times series for the four stations used in the activity, PowerPoint (PowerPoint 2007 (.pptx) 854kB Feb7 15) or the PDF version (Acrobat (PDF) 1.1MB Feb7 15)

For instructors only:

• Unit 4 activity instructor's key, PowerPoint -- private instructor-only file
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  Unit 4 activity instructor's key, PowerPoint

  
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Handouts, instructor notes, class PowerPoint files, and keys are suitable for a 50- or 75 minute class.

To modify this unit in combination with Unit 3 (Hazards at Divergent Plate Boundaries) for use in a single a two- to three-hour lab period, we recommend assigning the Unit 3 prework as a pre-lab assignment, and then in the lab session doing the Unit 3 classroom activity, followed by the Unit 4 prework as an in-class activity, followed by the Unit 4 classroom activity.

Formative Assessment

The wrap-up questions listed above in the "Description and Teaching Materials" serve as formative assessment, giving the instructor (and students) immediate feedback on how well they have understood the learning objectives of this unit. They also give the instructor opportunities to address misconceptions or gaps in understanding of unit content.

Summative Assessment

The following questions are designed to assess the learning objectives for this unit. Question 1 is intended for use as a test question, and Question 2 is intended as a homework question. However, both could alternatively be incorporated into a more extensive homework assignment, or could even be used as formative assessment as part of an in-class activity in a longer (e.g. 75-minute) class period.

1. In order to warn citizens and take effective action to save lives and property, emergency management officials need at least a few days of advance warning before a natural disaster such as a volcanic eruption occurs. Based on your experience monitoring Eyjafjallajokull, describe the monitoring data you would need, and the criteria you would you use with those data to decide when to issue a warning of a volcanic eruption. How would you differentiate the earliest indications that a volcano is waking up from the indications of an eruption?
2. Nyiragongo is a volcano in the Democratic Republic of Congo that sits in the East African Rift Valley, a divergent plate boundary. Its eruption of 2002 killed about 150 people, destroyed 15% of the city of Goma, and left 120,000 people homeless. View the 8 minute video from Television for Education: Asia Pacific found at http://www.youtube.com/watch?v=rZLSvO6vJZ0#t=40
   
   List at least four factors that prevented effective monitoring at Nyiragongo. Describe how each factor contributed to the negative consequences of this eruption.

For instructors only:

Unit 4 Assessment KEY, MSWord -- private instructor-only file

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PDF version -- private instructor-only file

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Rubrics

This rubric is used to assess student responses to the questions above based on three criteria. Responses are scored on a scale of 0-3, with 3 indicating mastery.

For question 1:

Requirement 1: Response to question 1 describes several methods geologists use to monitor geologic activity associated with volcanic eruptions. (Unit Learning Objective 1)

• 3 Points: Response accurately describes GPS, seismic monitoring, and other methods not discussed in the in-class work.
   
• 2 Points: Response accurately describes GPS and seismic monitoring.
   
• 1 Point: Response accurately describes GPS or seismic monitoring.
   
• 0 points: Response does not describe valid methods for volcano monitoring. 
   

Requirement 2: Response to question 1 describes specific signs of pre-eruptive activity and eruption in both GPS and seismic records. (Unit Learning Objective 2)

• 3 Points: Response describes both signs of pre-eruptive activity and eruption, in both GPS and seismic records. Descriptions are specific enough that the reader could identify such signs in a record.
   
• 2 Points: Response is missing one of the following: signs of pre-eruptive activity or eruption, in GPS or seismic records. Descriptions are specific enough that the reader could identify such signs in a record.
   
• 1 Point: Response is missing more than one of the following, or more than one of the following are vaguely described: signs of pre-eruptive activity or eruption, in GPS or seismic records.
   
• 0 points: Response does not describe valid methods for volcano monitoring.
   

For question 2:

Requirement 1: Response to question 2 describes factors that determine whether volcano monitoring can be effective in mitigating risk to people and property. (Unit Learning Objective 1)

• 3 Points: Response specifically describes at least four problematic aspects of monitoring at Nyiragongo, and explains how each contributed to the negative consequences of the eruption.
   
• 2 Points: Response specifically describes at least four problematic aspects of monitoring at Nyiragongo, but does not completely explain how each contributed to the negative consequences of the eruption.
   
• 1 Point: Response describes fewer than four problematic aspects of monitoring at Nyiragongo, and may or may not completely explain how each contributed to the negative consequences of the eruption.
   
• 0 points: Response dose not describe methods used for volcano monitoring at Nyiragongo.
   

• The 2010 Eyjafjallajokull eruption, Iceland, a report compiled in 2012 by The Icelandic Meterological Office (IMO) and the Department of Civil Protection and Emergency Management (DCP), June 2010.
  This is a large file! (5.8MB / 210 pages). This report contains a wealth of information on the 2010 eruption. The seismicity graph used in the exercise is extracted from page 58 of this report.
• Sigmundsson, Freysteinn et al., Intrusion triggering of the 2010 Eyjafjallajökull explosive eruption, Nature 468 (2010): 426-430.
  Source of the GPS time series data used in the classwork exercise.
• 1-page reference key to reading GPS time series, from UNAVCO
  This document describes of how to read 2-component times series (N/S, E/W); 3- component time series (N/S, E/W, up/down).
• Animation of earthquake activity associated with the 2010 eruption of Eyjafjallajokull
  Used in classwork (link is included in the PowerPoint presentation)