Seismicity and Relative Risk

Content learning goals

By the end of this activity, students should be able to

• Describe and interpret the distribution of earthquakes around the world
• Describe the types of data collected by earthquake monitoring programs
• Describe the difference between intensity and magnitude and how they are measured
• Describe how earthquake focal mechanisms relate to plate motion
• Describe the frequency of earthquake occurrence

Skills learning goals

By the end of this activity, students should be able to

• Navigate the U.S. Geological Survey Earthquake Hazards Program web site to find and collect real-time data about earthquakes
• Read a focal mechanism indicator and ShakeMap

Higher order thinking learning goals

By the end of this activity, student should be able to

• Predict the focal mechanism and effects of an earthquake based on its location
• Analyze the relative risks associated with a living in a variety of earthquake-prone regions.

This activity works well in an introductory earth science class at the college level. It must be taught in a computer classroom or on student laptops. I prefer that students work in pairs, so that they are discussing the data as they work with it. It could easily be modified for use in a more advanced course.

The first part of this module takes place in class, either in a computer lab or on students' laptops. Students work in pairs to explore real-time data available on the web at the U.S. Geological Survey Earthquake Hazards Program web site. The exploration takes the form of guided inquiry, and is interspersed with short lectures to clarify or introduce new concepts. Initially, students look at the distribution of recent seismicity around the world and in the United States, describing the patterns they see in the real-time data, and noting areas where they are surprised to see earthquakes. We have a class discussion where they volunteer ideas for why these earthquakes might occur in "unexpected" places. Then, they look in-depth into one large, recent earthquake to see what data is collected and made available. Again, we have a short discussion as a group about what these data are, and clarify any questions. Finally, they use this information to put the individual earthquake back into the context of the plate tectonic setting and describe how the data about earthquakes add to and reinforce what they already know about the processes occurring at different types of plate boundaries.

The second part requires students to work on their own to collect information about the relative risks associated with living in three different earthquake-prone sites. The students are asked to write a short paper summarizing the seismic hazards in three different cities (given by me) where they might attend graduate school, then to compare the risks associated with living in each location. In the end, they have to choose which city they will live in. This part is takes the form of more open-ended inquiry: students must determine which data about seismicity are most relevant to a discussion of risk, determine the appropriate questions to ask about those data, and make a decision. There is no right answer, but students must defend their choice.

The final part of the module takes place in class again. I compile the responses and show the results to the students. We discuss the results and they defend their choices as a group. The city with the largest number of votes is different every year, and I think it depends in large part on what has been going on in the news lately. This prompts a discussion about which factors students weighed differently and why and the inherently incomplete nature of the geologic record. I use this as an opportunity to give a brief lecture about the complex role that science plays in policy and decision-making and ongoing research into earthquakes and how students can get involved if they are interested.

Student Activity Sheet (Microsoft Word 42kB Jan22 12)
Lecture Presentation (PowerPoint 3.8MB Jan23 12)
Writing assignment and rubric (Microsoft Word 45kB Jan22 12)

This activity uses all freely available, real-time data on the web, so there is no need to download software or data. It can be challenging to integrate fully open-ended inquiry into any introductory course, but the geosciences face an additional challenge in the very large temporal and spatial scales on which geological processes operate. For that reason, working with real-time data and rapid geologic events such as earthquakes offers an ideal opportunity to engage students in inquiry: though the likelihood of obtaining new results is slim, the process that the students are engaged in is authentic, mirroring what geoscientists do. They are working with real data that everyone else is seeing for the first time as well.

Prior to teaching the module, I recommend going through the questions with current data and updating the slides to reflect recent earthquake activity. It is worth looking in detail at the current large earthquakes to see what students are likely to pursue in the first part of the module.

The writing assignment after the classroom-based exploration is assessed based on a 20-pt scale (see attached assignment and rubric). Since the students are exploring real-time data and assessing risk based on their own assessment of the hazards, there is no right or wrong answer, so they are graded based on completeness of answer. In order to fully answer this question, they need to be able to distinguish between types of earthquakes, the nature of the hazards associated with each, the relative risks involved living in each place, and the relative preparedness of each city.