Evaluating natural hazards data to assess the risk to your California home

Initial Publication Date: April 11, 2014 | Reviewed: July 21, 2015

Summary

For this assignment, imagine you are an emergency manager, property insurance agent, or simply a concerned property owner. In this role, you are to use a series of maps and natural hazard data to evaluate the risk to a building structure of your choice in the state of California. As a responsible assessor, you need to be aware of the exposure risk to the building. For each hazard, you will rate the potential risk in two dimensions: (1) Probability – The probability that a hazardous event "may" occur, and (2) Severity of Impact – A risk, by its very nature, always has a negative impact. However, the size of the impact varies in terms of cost and impact on health, human life, or some other critical factor.

You will assess the severity of the hazard to your building based on the extent (danger level) of previous, historic hazards that have occurred. After quantitatively assessing the probability and severity of the hazard to the building, you are to create a chart representing risk (probability x severity) of natural hazards to your building. After determining the top three hazards posing the most threat to your building, build a preparedness and mitigation plan for these hazards.

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Learning Goals

The WebGIS-based assignment is an excellent example of inquiry-based learning: students are given a specific question (e.g., evaluate the earthquake hazard at your house), and are steered toward the general data with which to answer this question (e.g., nearby plate boundaries and faults, historical earthquakes). Students are tasked with investigating and synthesizing large amounts of data to determine relevance to their individualized problem (e.g., evaluate the earthquake hazard at your house). WebGIS have the potential to enhance learning by creating a student-centered inquiry environment; this is particularly critical in the natural disasters courses, where the question posed to the student is suited to each individual. After exploring the hazards data, students are tasked with both graphically and verbally explaining their calculated risk results and communicating mitigation practices for the riskiest hazards. Thus, the assignment addresses both the communication and the understanding of the underlying geoscience as well as mitigation practices they can develop at their home.

Context for Use

This activity is written for entry-level, typically non-science, undergraduate students. Students should have a basic understanding of the mapped hazards (e.g., is an EF2 tornado more or less dangerous than an EF5?). The students need a computer with an internet connection to access to the WebGIS-mapped data. This activity is the "final project" for the course and is fairly lengthy (students are given 2 weeks to complete in 10-week quarter). Students will need to know how to use the WebGIS – particularly how to display data layers and how to use the measurement tool – though most students pick up these skills fairly easily after demonstration in the classroom.

Description and Teaching Materials

Risk Assessment, Part 1 Assignment File (Microsoft Word 178kB Apr11 14)
Risk Assessment, Part 2 Assignment File (Microsoft Word 168kB Apr11 14)

Teaching Notes and Tips

Guidelines include:
1. collecting the student's building address before the project and confirming it is appropriate for the mapped hazards dataset; for example, a student living in the desert near Barstow may not find this exercise as meaningful as a student living in Los Angeles and might be encouraged to look into using a family member's or friend's house.
2. Explain that proximity of previous hazards to their house is used as a proxy for probability of occurrence; for example, if they live near a long fault segment that has produced >M5 earthquakes in the past, the likelihood that this fault could produce another M5 in the future.
3. For probability, draw a simple example in the classroom first before the students explore the large WebGIS dataset. For example, draw a symbol representing the student's building and then draw symbols representing the earthquake at various distances from the building. Lastly, draw three "buffer" circles, or circles with a radius of 25, 50, and 100 mi, and ask the students if the earthquakes are close to the building (within the 25 mi circle) or far from the building (outside of the 50 mi buffer). If there are earthquakes have have occurred near the building then the probability is high. For severity, consider the magnitude or scale of the hazard. If these earthquakes are small in magnitude then the severity, or degree of damage, might be lower than if these are large magnitude events.

Assessment

Review the data investigation sections to determine if the student's proximity and damage scale answers are reasonable based on the submitted maps. Check that the student's calculated values of probability, severity, and risk make sense with the data. Overall learning assessment is best considered in the written questions at the end of the assignment where the student justifies the probability and severity values based on the observed data and the implications of the risk of the hazard to their building.

References and Resources

The webGIS sites are hyperlinked in the activity, but I include them here:
Part 1: http://bit.ly/MSln4d
Part 2: http://bit.ly/1ltsXkc
All data is freely available for download in either ArcGIS or Google Earth formats from California state or national government agency websites.