GEODESY AND SEISMOLOGY

Educational Outreach Strategy Involves Students in Earthquake Hazard Research

High school students in Alaska are helping scientists study earthquake hazards by conducting global positioning system measurements, which track slight movements in the Earth’s crust.

by J. Sauber, S. Stockman, and T. Clark, Laboratory for Terrestrial Physics, NASA's Goddard Space Flight Center, Greenbelt, Maryland

NASA has been making precise geodetic measurements to assess earthquake hazard associated with the subduction zone process in Alaska since 1984. In 1995, a new strategy for making geodetic measurements was implemented that included local residents in the measurement program, and in 1997, the program was expanded to include teachers and students at five high schools.

For the inhabitants of Alaska, understanding the hazards and underlying physical processes associated with earthquakes has immediate personal relevance. Large earthquakes occur yearly, great earthquakes have occurred during the lifetime of many residents, and the weekly testing of the tsunami warning system in coastal towns is a reminder of the devastation caused by earlier tsunamis generated near Alaska and serve as a cautionary note about future inundation.

In June 1995, Eric Linscheid, a Kodiak Island high school Earth science teacher, and seven of his students joined NASA researchers to conduct global positioning system (GPS) measurements at seven sites on Kodiak Island (Figure 1). On average, the Kodiak segment of the Pacific-North American plate boundary has experienced large earthquakes approximately every 60 years. This segment ruptured in the magnitude 9.2 earthquake of 1964. The geodetic stations span a 50- kilometer segment normal to the trend of the Aleutian megathrust above the portion of the plate interface where the shallow dipping slab (<10°) has slipped in large earthquakes and then bends into a steeper dip (>30°) that primarily slips aseismically. Repeated geodetic measurements at our sites will enable us to give local planners an estimate of the partitioning of ongoing strain accumulation across the populated region of Kodiak Island that is also the site of a satellite launch facility. We are also using the geodetic results to test alternate numerical models of this transitional slip zone.

Fig. 1. Location of geodetic sites (open diamonds) occupied in 1993, 1995, and/or 1997, and the permanent GPS site near Fairbanks (open square). The five boxes with the high school name on the right side indicate the observation region of each school. The shaded regions (with year) indicate the rupture zones of major earthquakes in southern Alaska during this century. The predicted rate of motion of the Pacific plate relative to a fixed North American plate is given by the vector in the lower right-hand corner.

The educational research program involved the students in research in support of the scientific investigation and increased their understanding of earthquake hazard in their local environment. The participation of local residents in the study enabled us to include a larger number of stations at a lower cost, since in the populated regions of Alaska personnel are required at the geodetic sites to safeguard the instruments. In 1995, geodesist Steven Nerem, who is now at the University of Texas, and surveyor Mark Bryant, who is now at ASHTECH in Reston, Virginia, taught the students the theoretical and practical aspects of GPS surveying and they insured data quality by checking the site set-up.

During the geodetic field campaign, science educator Stephanie Stockman conducted a qualitative research study on the students’ understanding of the scientific process and their perceptions of scientists. She found that the students had developed a sense of ownership and responsibility for their research sites, they demonstrated a deeper understanding of the process of science, and due to their interaction with the NASA scientists, they could look to them as role models. Following the 1995 observation program, Linscheid collaborated on research that led to a presentation at the Geological Society of America and a paper for the Journal of Geoscience Education; Web site: http://ltpwww.gsfc.nasa.gov/education/alaska.html.

The level of commitment and competence of the teachers and students encouraged NASA to expand the program to include more schools near our sites in southern Alaska. The other sites in the study are located where the northwestward-directed subduction of the Pacific plate is accompanied by accretion of the Yakutat terrane to continental Alaska (Figure 1). In this tectonically complex region between the transcurrent Fairweather fault and the Aleutian megathrust, recent crustal shortening and strike-slip faulting occurs offshore in the Gulf of Alaska (1987-1988, magnitude 6.9, 7.6, 7.6), onshore in the Chugach-St. Elias mountains (1979, magnitude 7.2), and in central Alaska on faults like the Denali fault. In contrast to the Kodiak region, and most other subduction zones, geodetic measurements can be made above much of the locked main thrust zone.

We used the horizontal rates of deformation estimated from GPS observations in 1993 and 1995 to estimate the extent and degree of coupling across the plate interface, as well as the seismic potential in this region. The study region in southern Alaska (Figure 1) includes the eastern segment that ruptured in the great earthquake of 1964. Detailed modeling of coseismic slip in the 1964 earthquake was used as input to alternate models of postseismic deformation. Additional observations in the future would enable us to discern strain localization associated with individual faults in the overriding plate and to constrain vertical rates of deformation that are critical for estimating the behavior of the crust and upper mantle.

In 1997, half of the sites in the Alaska research program were observed by students from five local high schools: Eric Linscheid and five students from Kodiak; Leroy Key and Darla Church and six students from Cordova; John Strang and four students from Valdez; Gene Crow and five students from Glennallen; and David Wellman and one student from Kenny Lake (Figures 1, 2, and 3). Grants were given to the five teachers to enable them to tailor the learning experience to their own educational objectives. The teachers then formulated their own programs in keeping with the measurement requirements.

Fig. 2. Kodiak high school teacher Eric Linscheid works with two of his students as they learn to set up the GPS antenna.

The program provided a first professional work experience for many of the students. Following the program, the soon-to-be seniors from Valdez were given letters of recommendation that could be used in college applications. It also offered scientists an opportunity to serve as role models for the students. The students gained experience with state-of-the-art technology. The students worked with NASA technologist Thomas Clark and ASHTECH surveyor Robert LeMoine to gain experience with GPS technology.

One of the objectives of the educational outreach program was to integrate the GPS study into the school's academic curriculum and extracurricular programs. For example, prior to the first day of observations on Kodiak Island, teacher Eric Linscheid and educator Stephanie Stockman conducted a geological field trip for Kodiak student researchers in order to integrate the GPS study into the school's Earth Science curriculum. The middle school students from Cordova were from the school's “'Future Problem Solving Program (Web site: http://www.fpsp.org/).” The grant money was used to supplement the general expenses of their program.

The GPS data acquired by the students were processed and these results were combined with geodetic measurements including trilateration, very long baseline interferometry (VLBI), and earlier GPS data. For instance, at the main Kodiak Island site, VLBI measurements were made between 1984 and 1990. GPS measurement were made in 1993, and with the help of the Kodiak Island high school students in 1995 and 1997 (Web site: http://denali.gsfc.nasa.gov/research/crustal_def/sauber_text.html). Based on the VLBI and GPS data, we estimated a site velocity of 11.6 ± 1.5 milimeters per year at N43°W ± 3°. This rate is lower than that predicted by a simple elastic dislocation model (17 meters per year) for a locked seismic zone of 150 kilometers wide and a 50 kilometer lower transition zone. Numerical models that incorporate a shorter locked segment and a viscoelastic Earth model can account for the observed velocity.

Fig. 3. Alaskan high school student checking his GPS set-up.

Perhaps of greatest societal importance, the program educated many residents about earthquake risk who would directly benefit from the results of the investigation. For example, most homeowners on Kodiak do not have earthquake insurance. Our study could allow the Kodiak citizens to make more informed decisions regarding earthquake hazard planning. Newspaper articles on the research program were featured in the Kodiak Daily Mirror, the Valdez Vanguard, and the Kenny Lake High School newspaper. While the above focuses on the benefit to the students and their communities, the teachers also saw the project as an opportunity for professional growth. This year, Linscheid was selected to analyze Gamma Ray Spectrometer data from NASA's Lunar Prospector mission as part of the “Space Explorers” program.

Future educational plans include facilitating the transfer of the earthquake hazard research program by seeking funding to place permanent GPS sites near some Alaskan high schools. The school partners would have full responsibility for these sites. Additionally, NASA is using the educational model of the Alaska program for some of its other projects, such as the Mars Orbiter Laser Altimeter Education Program. The outreach program was structured to educate and train teachers and students (Figures 2 and 3), engage them in NASA's scientific and technological enterprise by having them make GPS measurements, and then transfer the knowledge, and hopefully even the research program, to the people who care most about Alaskan earthquake hazard--the local inhabitants.

Source: Eos, August 18, 1998, p. 393.