Cascadia Great Earthquake and Tsunami Suite
I The Great Sumatran Earthquake and
Tsunami of December 2004
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II Is the stage being set for a Great
Cascadian Earthquake and Tsunami?
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III The Search for Great Cascadian
Earthquakes and Tsunamis in the Past
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IV Impact of a Great Cascadian Earthquake
and Tsunami on one Coastal Community
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V Rupture on the Seattle Fault: A Case
Study
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Natural Hazard Case Studies
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Unit IV. Great Earthquake and Tsunami Impact on a Coastal Community: Seaside
In this unit, students investigate the potential impacts of a magnitude 9+ earthquake and resulting tsunami on a small Cascadian coastal community, Seaside, Oregon. The unit presents with a regional map view of Cascadia in order to identify the location of Seaside at the north end of the Oregon coast. Students view an engaging animation of the body and surface wave fronts radiating from a shallow M9+ earthquake on the Cascadian subduction zone. The waves radiate in real time. Students figure out how long pronounced shaking lasts, which sets up a later investigation of evacuation scenarios in Seaside. The animation introduces a discussion of what built structures are vulnerable to shaking at different wavelengths.
A color map shows the regional variation of peak ground acceleration associated with such an earthquake, based on a USGS model. Students then deduce possible consequences of a scenario M9+ Cascadian earthquake, based on analogy with the M9.2 Alaskan earthquake of 1964. They measure the distance from Seaside to the plate boundary out at the continental margin, and then with a hypothetical speed of tsunami advance calculate the time interval between the earthquake and the arrival of the tsunami. This too sets up an evacuation scenario investigation later in the unit.
Students then view Seaside in close-up; the map base is derived from air photos, and shows significant cultural detail. They turn on layers showing the inundation extent of two ancient “local” tsunamis, based on stratigraphic data. One of these is associated with the “Orphan Tsunami” dating from the year 1700 that students investigate in detail in Unit 3. Finally, students open a layer showing the extent of “local” tsunami inundation derived from a USGS model, note the extent compared with that of known tsunamis, and define the “safe zone” that evacuees would have to reach.
The investigations then turn to the impact of a future great tsunami. Students view dramatic videos of inundation from the tsunami generated by the 2004 M9.3 earthquake off Indonesia in order to imagine an analogous scenario for Seaside. They view a dramatic simulation based on the results of physical model experiments of tsunami inundation at Seaside. They then view a map showing inundation wave heights expected, and investigate how the heights vary across Seaside.
Next, students are asked to imagine themselves to be the emergency manager of Seaside and to consider the high-priority factors in getting the highest number of people to safety following a great earthquake and before the expected tsunami inundation.
Finally, students investigate two simple evacuation scenarios, each involving some basic algebra. In the first, they measure the distance from one of the Seaside schools in the inundation zone to safety. A data table for the school gives the number of students in it. Using a simple scheme where people move after the most severe shaking has stopped, the time needed to move the columns to safety can be calculated. Knowing how long it will take for the tsunami to travel from its point of origin to Seaside, students can answer the question, do all the high school students make it to safety? A second similar scenario involves calculation of evacuation time from the Convention Center to safety, and asks how many people will make it.
Download project files now...
ArcGIS version
MyWorld GIS version
This material is based upon work supported by the National Science Foundation under Grant Number DUE-0521936. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.
In this unit, students investigate the potential impacts of a magnitude 9+ earthquake and resulting tsunami on a small Cascadian coastal community, Seaside, Oregon. The unit presents with a regional map view of Cascadia in order to identify the location of Seaside at the north end of the Oregon coast. Students view an engaging animation of the body and surface wave fronts radiating from a shallow M9+ earthquake on the Cascadian subduction zone. The waves radiate in real time. Students figure out how long pronounced shaking lasts, which sets up a later investigation of evacuation scenarios in Seaside. The animation introduces a discussion of what built structures are vulnerable to shaking at different wavelengths.
A color map shows the regional variation of peak ground acceleration associated with such an earthquake, based on a USGS model. Students then deduce possible consequences of a scenario M9+ Cascadian earthquake, based on analogy with the M9.2 Alaskan earthquake of 1964. They measure the distance from Seaside to the plate boundary out at the continental margin, and then with a hypothetical speed of tsunami advance calculate the time interval between the earthquake and the arrival of the tsunami. This too sets up an evacuation scenario investigation later in the unit.
Students then view Seaside in close-up; the map base is derived from air photos, and shows significant cultural detail. They turn on layers showing the inundation extent of two ancient “local” tsunamis, based on stratigraphic data. One of these is associated with the “Orphan Tsunami” dating from the year 1700 that students investigate in detail in Unit 3. Finally, students open a layer showing the extent of “local” tsunami inundation derived from a USGS model, note the extent compared with that of known tsunamis, and define the “safe zone” that evacuees would have to reach.
The investigations then turn to the impact of a future great tsunami. Students view dramatic videos of inundation from the tsunami generated by the 2004 M9.3 earthquake off Indonesia in order to imagine an analogous scenario for Seaside. They view a dramatic simulation based on the results of physical model experiments of tsunami inundation at Seaside. They then view a map showing inundation wave heights expected, and investigate how the heights vary across Seaside.
Next, students are asked to imagine themselves to be the emergency manager of Seaside and to consider the high-priority factors in getting the highest number of people to safety following a great earthquake and before the expected tsunami inundation.
Finally, students investigate two simple evacuation scenarios, each involving some basic algebra. In the first, they measure the distance from one of the Seaside schools in the inundation zone to safety. A data table for the school gives the number of students in it. Using a simple scheme where people move after the most severe shaking has stopped, the time needed to move the columns to safety can be calculated. Knowing how long it will take for the tsunami to travel from its point of origin to Seaside, students can answer the question, do all the high school students make it to safety? A second similar scenario involves calculation of evacuation time from the Convention Center to safety, and asks how many people will make it.
Download project files now...
ArcGIS version
MyWorld GIS version
This material is based upon work supported by the National Science Foundation under Grant Number DUE-0521936. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.