Initial Publication Date: January 11, 2018

In the Trenches - January 2018

Seismology Lessons with Deep and Lasting Impact

Volume 8, Number 1

In This Issue

Online Supplements

This site provides web links that supplement the print articles as well as news and web resources. Members can follow the "Read more" links below to access full versions of the articles online. To receive the full edition of In the Trenches, join NAGT

Using Models to Develop Deep Understandings of Earthquakes

Nicole LaDue, Northern Illinois University; Michael Hubenthal, the IRIS Consortium; and Glenn Dolphin, University of Calgary

Earthquakes are a popular topic with both students and teachers. Their unpredictable nature and potentially catastrophic effects command attention and pique curiosity. As instructors, it is common for us to take advantage of earthquakes as seismological "teachable moments." However, we are also responsible for developing our students' fundamental understanding of "how" and "why" earthquakes occur and how they fit within the larger Earth system. Read more...

Bending Rocks in the Classroom

Michael Hubenthal, the IRIS Consortium

How a rock responds to stress is a concept critical to forming explanatory models in the geosciences. While your students are likely to have had lots of experience with rocks, few will have experienced them behaving elastically. As a result, most will think of rocks as rigid solids (Hubenthal, 2015), something which impedes learning of concepts such as the elastic rebound theory. It is possible to bend rocks and minerals in class to demonstrate their elastic property (e.g., returning to their original shape and size after the forces deforming them have been removed). Read more...

Teaching Fault Asperities with Spaghetti

Nicole LaDue and Josh Schwartz, Northern Illinois University

Rocks deform, or change shape, as a result of stress. In one geologic setting, like a fault, rocks can experience multiple types of deformation. A fault exists where there are large fractures in geologic bedrock along which there has been movement in the past. This is evidence that the rock has experienced brittle deformation. As stress builds up around a fault the rocks will bend on either side of the fault. When the stress gets great enough, the rocks will slip (or move) relative to one another, releasing stress and returning the rocks to their original pre-bent shape. The geologic event that occurs when the rocks move is called an earthquake. Read more...

ONLINE EXTRA: Constructing an Asperity Model

Use a 1/8" round over bit in table router to round over the top sides, ends and the vertical corners of the wood block. On the table saw set the saw depth to 1/8" and the fence to 0.5". With the rounded over top of the block facing down and the side against the fence, cut a groove through the block. Move the fence in increments of 1/4", cutting a groove each time, until you have 15 grooves and you should have about 0.5" left on the block. Read more...

Modeling the Role of Elasticity in Earthquakes

Glenn Dolphin, University of Calgary

Understanding what an earthquake is and how one happens is not a straightforward task for novice geoscience learners (Francek, 2013). Understanding the mechanism (elastic rebound) and its unpredictability, in both time and magnitude, can be very challenging. To (safely) afford students an earthquake experience, a model like the earthquake machine (Hubenthal, Braile, & Taber, 2008) can be instructive. This article describes how to build your own earthquake machine and provides ideas for the types of inquiry that you can conduct as you implement such a model in class. Read more...

ONLINE EXTRA: Learners and Learning as a Foundation for Competent Earthquake Instruction

Nicole LaDue, Northern Illinois University; Michael Hubenthal, the IRIS Consortium; and Glenn Dolphin, University of Calgary

In spite of being societally relevant and engaging to learners, earthquakes can be a challenging topic to comprehend as the underlying physical processes cannot be directly observed. Research shows that students have difficulty learning content that occurs outside the range of everyday human activity (i.e. large timescales, extremely small or large spatial scale) (Jones et al., 2009; Tretter et al., 2006). For instance, elastic rebound theory explains accumulation and release of earthquake energy (see Dolphin in this issue). In this process, large sections (i.e.100s of square kilometers) of Earth's rigid outer layer (i.e. the lithosphere) slowly deform, on timescales ranging from 10s to 100s, or even 1000s of years. Read more...

ONLINE EXTRA: The History of Elastic Rebound Theory: How a Big Disaster Helped Us Better Understand How the Earth Works

Glenn Dolphin, University of Calgary

By the early 1900s, a full 25% of the US population located west of the Rocky Mountains lived in and around San Francisco. There were 17 cable car lines, 37 banks, and three opera houses. The city rivaled New York for imports and exports and became known as The Jewel of the West, and Paris of the Pacific. During the early morning hours of the 18th of April in 1906, the earth began to shake violently in what was later classified as a magnitude 7.8 earthquake.
Read more...

ONLINE EXTRA: Using GPS Velocity Vectors to Illustrate Elastic Rebound

Michael R. Brudzinski, Miami University

Many of the different models for elastic rebound described in this issue are driven by the difficulty in creating a visualization of the actual process that operates on faults. Rocks near a fault are bent on the order of a few meters relative to rocks far from the fault, but this bending can occur over tens of kilometers of distance. The gradual bending near active faults can build up over tens to hundreds of years, but when an earthquake occurs, the rocks move in matter of seconds. Students typically see only the results of an earthquake, such as the offset of a fence built across a fault, but not the gradual motion that precedes an earthquake. Read more...

ONLINE EXTRA: Quantitative Reasoning in the Geoscience Classroom: Modeling Functions and Logarithmic Scales

Victor J. Ricchezza and H.L. Vacher, University of South Florida

Have you ever tried presenting graphs to your students only to experience frustration when they look first to the data points, ignoring important information on the graphical axes? Does this frustration lead to a less quantitative presentation of your course—do you leave the graphs (or the math behind them) out entirely? Geoscience courses are often viewed as being qualitative, despite the fact that modern geoscientists practice in a thoroughly quantitative field. Enhancing our students' skills and experience in quantitative reasoning in undergraduate geology courses can be difficult, but it is essential if students are to work successfully in the profession after graduation. Read more...

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Web Features

NAGT, its members, and its sponsored projects have produced a number of resources related to the topics addressed in this issue.

The Science Education Resource Center Site Guide to Teaching About Earthquakes»

This site guide provides access to earthquake-related teaching materials such as teaching activities, visualizations, tools, and datasets. Explore our collections of materials for teaching about earthquakes using data, simulations, and models, teaching geophysics, and teaching about hazards in introductory courses.

Teaching Activity: The 2014 La Habra earthquake—Teaching Risk and Resilience in Southern California with Citizen Science»

This teaching activity, part of the On The Cutting Edge peer reviewed teaching activities collection, invites students to students examine seismic waveforms recorded during the M5.1 La Habra earthquake and place their observations in the tectonic framework of southern California. The students will make basic observations regarding the location of the earthquake based on seismic waveforms collected by the Southern California Seismic Network (SCSN), and compare the waveforms with those collected by a low-cost sensor installed in a nearby school through the Quake-Catcher Network (QCN). The QCN is a citizen-science program, where schools, offices, and homes adopt a sensor, and learn about earthquake science. Students will evaluate the performance of these sensors compared with more costly SCSN sensors, and whether the use of these sensors can provide an effective tool in the promotion of earthquake science education on risk and resilience. To conclude the activity, students will communicate their findings in a 'think, pair, share' activity, and discuss the potential seismic risk and economic impact in the region with a classmate.

Teaching Activity: Examining Your Earthquake Hazard»

In this teaching activity, developed by Eric Baer and Carla Whittington of Highline College, students look at their seismic hazard and then determine the likelihood that their residence will be uninhabitable after 500-year return interval quake. The student goals of the activity include learning what seismic hazard is, learning to relate shaking to intensity, and learning about the relationship between intensity and damage to structures.

Teaching Activity: Izmit Earthquake»

In this teaching activity, part of the On the Cutting Edge Exemplary Teaching Collection, students analyze earthquake seismicity from the North Anatolian fault using a variety of methods. Students have the opportunity to make and interpret an earthquake focal mechanism from scratch, and the additional portions of the lab provide regional context and historical data to develop a better understanding of seismicity in Turkey.

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