Education and Outreach Based on Data from the Anza Seismic Network in Southern California

Transcription

1 Education and Outreach Based on Data from the Anza Seismic Network in Southern California D. Kilb, R. L. Newman, F. L. Vernon, J. A. Eakins, L. Ziegler, J. Bowen, and J. Otero Cecil H. and Ida M. Green Institute of Geophysics and lanetary hysics INTRODUCTION Innovative and exceptional education and outreach services often require collaborative efforts from diverse members of the scientific community, educators, emergency response personnel, and the media. This collaboration is essential when large earthquakes occur in highly populated regions where detailed and accurate information is required immediately to assure the safety of the general public. To streamline these interactions the Anza group has taken the following steps: (1) When we respond to large earthquakes globally, or smaller earthquakes locally, we collaborate with other research institutions, such as SCEC and the IRIS-DMC, to provide information quickly and effectively to the general public and emergency response personnel. (2) In the event of a major earthquake within our area of responsibility we provide data to other researchers as needed and collect data from them to support our efforts. (3) The Anza group makes a special effort to meet the needs of the local educational community through cooperation in the development and maintenance of educational modules. While our raw data are readily available, some end users prefer additional assistance in data manipulation and interpretation. We frequently provide our services to assist others in specialized uses of our data. These efforts include the incorporation of real-time seismic displays in museum settings (see later in this paper). Through these efforts, the Anza group extends the value of the Anza seismic data to include broadening the common seismological knowledge of San Diego residents and visitors. (4) We have held planning sessions with the local utilities companies (e.g., SDG&E) to understand their needs better in the event of a large earthquake in southern California. (5) We have routinely dealt with the media in response to relatively small earthquakes in our region and expect that these interactions have prepared us to respond quickly and efficiently to more dire situations. (6) We maintain ~100 Web pages that distill, explain, and display data from the Anza seismic network. Visitors to these pages include the general public, San Diego based media (television, radio, and newsprint), national and international geophysical researchers, statisticians, and educators at multiple levels. THE ANZA SEISMIC NETWORK: DATA COLLECTION AND DISSEMINATION The Anza seismic network consists of sixteen stations with broadband and strong-motion sensors, one station with only a broadband sensor, and twelve stations with strong-motion sensors. These stations compose a digitally telemetered array straddling the San Jacinto Fault zone (SJFZ) in southern California (Figure 1). Data recorded by these seismic instruments are telemetered to the Cecil H. and Ida M. Green Institute of Geophysics and lanetary hysics (IG) in La Jolla, California with only a few seconds lag time (i.e., realtime) between the seismic recording and the waveform packet arrival at IG. Anza data are shared in real-time with San Diego State University for use in its educational program and media presentations. The IRIS Data Management Center maintains a copy of our data archive that is updated in realtime. To augment TriNet data, Anza data are also delivered in real-time to the Southern California Earthquake Center (SCEC), which allows personnel at California Institute of Technology (Caltech) to use both data sets in their determinations of earthquake locations and magnitudes. A master composite earthquake catalog is submitted by Caltech to the Advanced National Seismic System (ANSS). The complete Anza waveform data set, which consists of more than 58,000 events, is stored at IG online in a RAID (redundant array of inexpensive disks) mass-storage system. These data are stored in miniseed format, complete with CSS3.0 format database tables of instrument response and source parameters. Researchers from academia and industry have complete access to all archived Anza data directly through user accounts at the University of California at San Diego (UCSD), and current data can be accessed through an Object Ring Buffer (ORB), a mechanism by which data are buffered and transported from one machine to another via a network connection using Antelope software (BRTT, 2003). 522 Seismological Research Letters Volume 74, Number 5 September/October 2003

2 35 0 km 50 n Sa o nt ci Ja 34 El sin lt au W DM lt n Sa R R W WM O SND SND N CRY C TR B BZ FRD D VA2 A r nd A ef u fa R or Salton S n M MT M lf ria o E pe Im an LV f THS L S o nt ci Ja HWB yon 33 lt au USA Mexico ou Tr Figure 1. The Anza seismic network. Current operational Anza stations (inverted blue triangles), earthquakes (red points), surface fault traces (orange lines) with the most important ones named, major highways (solid gray lines). Names of the major faults are listed in addition to the Anza seismic station codes. Station MTR, at Mission Trails Regional ark, was installed in February 2002 as part of a joint education and outreach project with the park and SDSU/ IG/UCSD. More than 58,000 earthquakes have been recorded by the Anza seismic network over the last 21 years. Here we show a representative subset of ~31,000 earthquakes. Individuals can also obtain data by submitting data requests through the Southern California Earthquake Center (SCEC) Data Center (SCEC, 2003), the IRIS DMC, or our local Web-based data query tools ( We also accommodate other methods of data transfer as requested by end users, such as waveform data in SEED or SAC format. Real-time Seismic Event Maps We maintain XML-based near-real-time seismic event maps that were developed specifically for displaying the Anza seismic network data (see anza). On average ~2,500 visitors per month explore these pages. These scaleable, topographic event maps are updated every 10 minutes to include new events and/or to incorporate a seismic analysts refined earthquake location(s). The pages provide a high level of interactivity where the user can toggle between local, regional, statewide, continental, and global reference frames. Each reference page lists the last two weeks of events (limited to 300 maximum) recorded by the Anza seismic network, and each display map includes earthquake locations that are color-coded with respect to the time the earthquake occurred, and the size of the event marker reflects the earthquake s magnitude. Each clickable event marker takes the visitor to a subsequent Web page that contains information about the specific event of interest. If a specific Seismological Research Letters September/October 2003 Volume 74, Number 5 523

3 event has multiple event locations determined by different centers (such as TriNet, USGS, UCSD, or the appropriate authoritative center), the associated event page lists all solutions, with the preferred location at the top of the list. USING WEB-BASED INFORMATION IN THE CLASSROOM The Anza network s comprehensive Web site ( eqinfo.ucsd.edu) offers traditional earthquake awareness material such as current seismicity, seismic hazards, historic earthquake information, and specifications about the Anza databases, seismic stations, and hardware configurations. We also maintain specially developed educational pages geared toward the K 12 Earth science curriculum that include a user-interface data extraction tool and an online glossary containing definitions for the specialized vocabulary surrounding geophysics and seismology ( Using these pages, the level of learning can be modified to fit the skills of the students. Beginning students can use the seismicity distribution to identify major faults, while the more advanced classes can investigate questions such as which seismic network would give the most accurate estimate of earthquake depth for an earthquake in Memphis, Tennessee, what type of seismic sensor (e.g., strong-ground-motion sensor or a broadband sensor) is designed to record both large and small earthquakes, and which earthquake fault is more active in southern California, the San Andreas or the San Jacinto Fault. Seismograms can also contain information that does not pertain to earthquakes. To introduce the wealth of knowledge contained within the seismic wave noise, our Web pages contain examples of different causes of noise sources. Seismic noise signatures that can be readily identified include hurricanes (Figure 2A), traffic patterns, and indications of the general public experimenting with the seismic sensor installed at a local San Diego museum (see Mellors et al., 2003, this issue). We strive to provide complementary text and images, with the specific purpose of serving the educators and emergency responders in the San Diego region, to augment the wealth of information on earthquakes, seismic hazards, and earthquake mechanisms that are currently available on the Internet. Reasonably, some information such as the USGS Did You Feel It? page should be housed in only one location, and whenever appropriate we direct our Web visitors to this Web site. Some duplication of seismic information, however, is often helpful in teaching aspiring scientists to check diverse sources to determine the most appropriate dataset for the task at hand. For example, if the student is interested in an earthquake that occurred at the border between southern California and Mexico, due to the close proximity of an earthquake in this region to the Anza seismic array, the Anza Web pages would be the best place to find high-resolution data from the event, whereas small earthquakes that are more distant to the Anza seismic network will likely be recorded with better resolution by other networks, such as some of those listed on our Relevant Links Web page. Of local interest to educators in the San Diego region are the digital seismic recordings from Anza network station SOL in La Jolla, California. Examining this in our backyard data is fun for students of all ages. Data from this station, and others in the Anza network, were highlighted in an undergraduate introductory Earth science class at UCSD called The lanets, in which the professor discussed with her students many of our special event pages, including the 29 April 2003 magnitude 4.9 Fort ayne, Alabama earthquake and the three anomalously large earthquakes (all over magnitude 6.7) on Memorial Day weekend Earthquake Education through Web-based Interactivity To challenge visitors, we maintain an Online Earthquake Quiz that includes an in-depth answer page with links to supplemental information. We augment this with a more detailed discussion of questions regarding notable seismic phenomena, such as Why did the Solomon Islands in the South acific experience so many earthquakes in September 2002? and Why does Oregon have so many earthquakes? These explanations are designed specifically with education in mind. We have also developed interactive Web media objects (such as Flash animation and QuickTime movies) that describe in detail how seismic data are recorded by our network and how these data arrive at IG and are then disseminated. Detailed information is also available about research projects such as the planned USArray seismometer deployment, where we have developed a Flash animation illustrating the migration of the seismometers across the United States. Real-time Seismic Data: In the Classroom and on Display Based on extensive interest expressed during our pilot education/outreach programs we have designed a prototype Web page that streams a real-time display of continuous seismic waveforms recorded by the Anza seismic network. Our current displays include data from all stations in the Anza seismic network in a 12-hour time window with automatic earthquake detection triggers and seismic -wave arrival times at individual stations highlighted. The lag time between the recording of the seismic waves and the seismic display is only a few seconds. We are currently working on increasing the flexibility of this program to allow the user to specify which station(s) and channel(s) to display and bounds on the temporal limits of the continuous seismic waveform(s). Ultimately we want to include additional features such as the ability to filter the waveforms or see the frequency spectrum of a user-defined data snippet. Working in tandem with researchers from SDSU, the Anza network group deployed and helps maintain a real-time seismic data display at the Mission Trails Regional ark (MTR) in San Diego (see Mellors et al., 2003, this issue). This exhibit consists of both a seismic sensor and a large screen display of continuous seismic waveforms, both from the MTR station and from other stations in the Anza network. Visitors can immediately see the recording of their 524 Seismological Research Letters Volume 74, Number 5 September/October 2003

4 (A) BZN CRY FRD KNW LVA2 MON FO RDM SND SOL TRO WMC 9/26/01 12:00AM 9/27/01 6:00M 6 hrs (B) 10 seconds (C) 10 min Figure 2. Sample images from our special events Web pages ( (A) Seismic signature of hurricane Juliette (26 September 1 October 2001) as it traverses the Anza seismic network array. Here we display the vertical components of each seismic station that include approximately two days of data, with the oldest data at the left-hand side of the figure (starting around midnight Wednesday, 26 September 2001). (B) Recording of a local M 4.2 earthquake (23 May 2003) near Brawley, California. Note the seismic energy arrives at station YAQ first, indicating that the earthquake is closest to that station. (C) Teleseismic recording of the M 6.9 earthquake (26 May 2003) near the east coast of Honshu, Japan as recorded by the Anza seismic network. Note that the arrivals of the waves ( flags) are synchronized across the network, indicating the event was distant. Seismological Research Letters September/October 2003 Volume 74, Number 5 525

5 stamping on the ground in feet-on (instead of hands-on) learning. We assisted with the deployment of a similar display, primarily used for teaching at the college level, in the geology department at California State University at Long Beach. In addition to working cooperatively on the real-time data display in museum settings, the Anza group developed and maintains a large, two-screen display of real-time seismic information (maps and waveforms) in the public foyer at IG/UCSD (Figure 3A). These digital seismic displays continuously stream data and update event location maps a significant upgrade from the old method of displaying seismic recordings with pen and paper on drum recorders. We have taken initial steps to have an improved display at the Birch Aquarium at Scripps as well as at the Museum of Natural History in Balboa ark in San Diego. Both of these museums have more than 400,000 visitors per year. The Anza network data are an important educational tool at multiple levels. They have been used in educational programs targeted at high school students nationwide and at local San Diego 6th grade students. In both venues the seismic data are viewed and delivered in real-time. The Anza seismic network group has also worked extensively with the Visualization Center at Scripps ( to supply data and images for teacher workshops on earthquake education (see Kilb et al., 2003, this issue). One of the most extensive educational uses of the Anza data is to the educational rinceton Earth hysics roject (E), in which professor Gary avlis of Indiana University distributes the data to 31 high schools throughout the U.S., prompting students to learn how to determine an earthquake s location, depth, and magnitude from the associated seismic waveforms. The Anza data are also used in higher education. Dr. Frank Vernon at IG/UCSD routinely uses Anza data in both his time-series analysis class and his weekly record-reading class. In these classes, the students analyze seismograms and, for example, compare and contrast the similarities and differences of teleseismic and local events (Figures 2B C). Anza network data have also been used for introductory geoscience laboratory exercises on earthquake location at San Diego State University (Mellors and Girty, 2000). Additionally, five h.d. dissertations at IG, as well as at least two from other universities, have been based on Anza data (e.g., Vernon, 1989; Scott, 1992). At present, we have two postdoctoral researchers who are using Anza data in their research (e.g., Kilb et al., 2002). Anza seismic data have also been used in numerous published seismic studies, many of which have been the focus of graduate student seminars. These works include studies of coherence of seismic waves (Vernon et al., 1991) and teleseismic -wavefront deflections (elkum et al., 2003) among many others (e.g., Berger et al., 1984; Fletcher et al., 1987; Aster et al., 1990; Hartse et al., 1994; Li and Vernon, 2001). More than thirty undergraduate students have participated in data processing and data analysis (Figure 3B) over the past 10 years, and many of these students have gone on to work in earthquake research or engineering fields. REARING FOR LARGE EARTHQUAKES IN SOUTHERN CALIFORNIA: ASSISTING EMERGENCY RESONDERS To supply real-time seismic information to the general public and emergency personnel through our Web-based interface the Anza network team continually updates its Web-based information. For example, within hours after the 1999 Hector Mine earthquake struck southern California (2:45 AM local time), our initial public Web page detailed the earthquake s location, magnitude, and Anza-network-recorded seismic waveforms of the analyst-reviewed mainshock. Extracted waveforms in SEED format were immediately available, and requests for SAC format data were also met. Web-accessible maps were updated daily to display the latest aftershocks, and waveforms were provided for significant aftershocks. Effort has been made to more efficiently automate the display of the seismic information on these special event Web pages. Tests of this automation process are ongoing and have proved useful for the last ~25 special event pages we created within the last year. FUTURE DIRECTIONS With the rapid development of both broadband and wireless technologies, and the reduction in cost of the associated hardware, we are planning to expand the Anza real-time network to provide more coverage in San Diego County. The addition of new stations in our network will enhance our understanding of the processes associated with earthquakes. Concurrent with this expansion is the continued development of our Web presence. This will include the translation of all of our Web pages into Spanish, which will allow a greater number of visitors access to our Web site, especially our neighbors in Mexico. The automated real-time Web pages that illustrate seismic activity in the region are written in XML, which is a universal data format, and presented through XSLT style sheets. This allows the data to be viewed not only by Web browsers but also by ersonal Digital Assistants (DA s) and WAenabled cellular telephones. Development is in progress to port our data sets into these other media. A tool that has tremendous potential in teaching seismology to the general public, especially in terms of how earthquakes travel through the Earth and are detected at different stations at different times, is the WiggleView Open GL application developed by researchers at the Electronic Visualization Laboratory at the University of Illinois at Chicago with funding by IRIS. The application imports and displays threecomponent seismic waveforms (x, y, z) for specific earthquakes at station locations across a 3D global base map. This map can be rotated, enlarged, and shrunk and the waveforms at each station can be enlarged or shrunk, which allows close examination of individual stations and regional or global views of network arrays. This application also has a 3D interface that can be viewed on 3D visualization systems such as 526 Seismological Research Letters Volume 74, Number 5 September/October 2003

6 (A) (B) Figure 3. (A) Seismic display in the Munk Laboratory foyer at IG/SIO/UCSD includes clickable maps, the Anza network array map, and background information on what is being shown (left display) and real-time continuous waveforms recorded by the Anza seismic network (right display). The right upper window shows the last 24 hours of data and the right lower window shows the last 30 minutes of data. (B) Analyzing continuous waveforms recorded by the Anza seismic network, UCSD undergraduate student John Stivers determines earthquake locations using the Antelope software package ( Seismological Research Letters September/October 2003 Volume 74, Number 5 527

7 the Geowall. The Anza group is currently working with the authors of the application to stream our continuous real-time seismic data through the WiggleView application, which will allow immediate import and display of seismic events autodetected by the Anza seismic network. CONCLUSIONS The Anza real-time broadband network provides up-to-theminute seismic data and information to a wide and diverse audience, both directly through our extensive Internet presence and indirectly through the data we provide to other government data centers and individual researchers. The network combines hardware technology developed offsite with software developed by commercial vendors and our internal IG/UCSD researchers and programmers. This kind of service is fundamentally important to both the scientific community and the general public living in regions of high seismic activity, such as southern California. ACKNOWLEDGMENTS This paper was greatly improved based on reviews by Doug Given and Lisa Wald. Essential to the smooth operation of the Anza seismic network is work of our Senior Development Engineer Glen Offield. We thank Delia Constant for assisting us with our glossary page. This research was supported by the U.S. Geological Survey (USGS), Department of Interior, under USGS award number 01HQAG0021. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. government. REFERENCES Aster, R.,. Shearer, and J. Berger (1990). Quantitative measurements of shear-wave polarizations at the Anza seismic network: Southern California implications for shear-wave splitting and earthquake prediction, Journal of Geophysical Research 95, 12,449 12,474. Berger, J., L. M. Baker, J. N. Brune, J. B. Fletcher, T. C. Hanks, and F. L. Vernon III (1984). The Anza array: A high-dynamic range, broadband digitally radio telemetered seismic array, Bulletin of the Seismological Society of America 74, 1,469 1,481. Boulder Real-Time Technologies (2003). Fletcher, J., L. Haar, T. C. Hanks, L. Baker, F. L. Vernon III, J. Berger, and J. N. Brune (1987). The digital array at Anza, California: rocessing and initial interpretation of source parameters, Journal of Geophysical Research 92, Geowall (2003). Hartse, H., R. Aster, M. Fehler, J. Scott, and F. Vernon (1994). Smallscale stress heterogeneity in the Anza seismic gap, southern California, Journal of Geophysical Research 99, 6,801 6,818. Kilb, D., J. Hardebeck, A. Hindley,. Shearer, J. Eakins, and F. Vernon (2002). Waveform and Focal Mechanism Heterogeneity in Aftershocks of the 10/31/2001 M5.1 Anza, California, Earthquake: Why and Where, SCEC meeting. Kilb, D., C. S. Keen, R. L. Newman, G. M. Kent, D. T. Sandwell, F. L. Vernon, C. L. Johnson, and J. A. Orcutt, (2003). The Visualization Center at Scripps Institute of Oceanography: Education and outreach, Seismological Research Letters 74, Li, Y. G. and F. L. Vernon (2001). Characterization of the San Jacinto Fault zone near Anza, California, by fault zone trapped waves, Journal of Geophysical Research 106, 30,671 30,688. Mellors, R. J., E. Riggs, J. Eakins, F. Vernon, and. Kilburg (2003). A Real-time Interactive Educational Seismology Exhibit, Seismological Research Letters 74, Mellors, R. J. and G. H. Girty (2000). A Web-based seismology module for introductory Earth science classes (abstract), Seismological Research Letters 71, 241. elkum, V., F. Vernon, and J. Eakins (2003). Large teleseismic wavefront deflections observed with broadband arrays, Bulletin of the Seismological Society of America 93, Sanders, C. O. and H. Kanamori (1984). A seismotectonic analysis of the Anza seismic gap, San Jacinto Fault zone, southern California, Journal of Geophysical Research 89, 5,873 5,890. Southern California Earthquake Center (2003). Scott, J. S. (1992). Microearthquake Studies in the Anza Seismic Gap, h.d. thesis, University of California at San Diego. Vernon, F. L. III (1989). Analysis of Data Recorded on the Anza Seismic Network, h.d. Thesis, University of California at San Diego. Vernon, F. L. III, J. Fletcher, L. Haar, A. Chave, and E. Sembera (1991). Coherence of seismic body waves from local events as recorded by a small aperture array, Journal of Geophysical Research 96, 11,981 11,996. Cecil H. and Ida M. Green Institute of Geophysics and lanetary hysics IG/UCSD MS 0225 La Jolla, CA hone: Fax: dkilb@epicenter.ucsd.edu 528 Seismological Research Letters Volume 74, Number 5 September/October 2003