http://www.edcenter.sdsu.edu/ssc-scec/index.html

Sara Whipple* and Robert J. Mellors**
San Diego State University
*Education Center on Computational Science and Engineering
**Department of Geological Sciences

Launch the Earthquake List

Abstract

Web-based technologies are used to share information from the Southern California Earthquake Center (SCEC) with the California Seismic Safety Commission (CSSC) in an automatic and near real-time manner. The purpose of this project is to automatically extract subsets of data from SCEC databases and integrate this information with other available online databases to provide a quick and efficient summary of data to the CSSC. The near real-time Earthquake List has been developed as a pilot program. The CSSC is primarily interested in larger earthquakes that may potentially damage persons or property. The Earthquake List is a working model tested for magnitudes greater than 3.0 that will be able to provide useful information in the infrequent occurrence of a larger event.

SCEC online data include comprehensive and rapidly updated earthquake catalogs. A subset of this information is extracted, converted to XML, and combined with information from the US Geological Survey (USGS) and Census Bureau Tiger database using Extensible Stylesheet Language Transformations (XSLT), Java servlets and Java applets and the result is rendered as a two-dimensional map. The Census Bureau Tiger database provides mapping capabilities that are combined with feature data acquired from the USGS to automatically generate an online map showing the earthquake epicenter and nearby cities, as well as bridges, tunnels, hospitals and airports within a 10-mile radius of the event. This information is automatically generated and available online within minutes of an earthquake.

Introduction

One of the primary goals of the SCEC is to transfer knowledge and understanding about earthquakes by communicating with scientists, engineers, emergency managers, government officials, and the general public. To help accomplish this objective SCEC has chosen to develop innovative web technologies that provide dynamic content for the CSSC website. This proposal to the California Seismic Safety Commission offers website enhancements that include a near real-time and automatically updated interactive Earthquake List and dynamic mapping solutions.

The Earthquake List is a web interface that uses XML and XSLT to generate a list of recent earthquakes in California. The advantage of using XML for this project is that it gives the user the ability to query the list of earthquakes by magnitude. This allows for the elimination of micro quakes and permits the general public and the CSSC to focus on the larger and potentially more damaging events without the loss of data. The Earthquake List also gives the user the option of generating a map of where a particular earthquake occurred.

Project Goals

Main Goal:
To automatically extract subsets of data from SCEC databases and integrate this information with other available online databases to enhance CSSC website content.

Specific Goals:

• Employ Java technology to automatically access Recent Earthquake data from the SCEC website and convert acquired data into XML.
  Use XSLT in combination with Java servlets to parse the XML data and create a web interface that allows the user to query the earthquake data by magnitude and provides an option for the user to generate a map of where an earthquake originated.
  Gather demographic information from other online databases and convert it to XML via a Java routine.
• Utilize the Census Bureau's online TIGER Mapping Services to dynamically generate maps that encompass the earthquake's epicenter and surrounding topography. Use Java applet technology in conjunction with XSLT to query the demographic data and overlay features such as bridges and hospitals on the map. Employ Java Swing technology to create a graphical user interface (GUI) that allows the user to be able to interact with the overlaid demographic map data.
• Explore other avenues of enhancing the content of the CSSC website, including exporting data from the Electronic Encyclopedia of Earthquakes in XML format and experimenting with visualization tools for educational purposes.

Methods

Develop XML DTD and XSLT Stylesheets
As this project aimed to employ innovative web technologies, Extensible Markup Language (XML) was selected as the foundation for handling the datasets. In order to convert existing data into XML, it was necessary to develop a logical and well-formed XML Document Type Definition (DTD) to contain the data. Structured and self-descriptive XML is important because it eases the process of sharing information between different parties. Another necessity of working with XML was to learn how to use Extensible Stylesheet Language Transformations (XSLT). XSLT is a language for transforming XML documents into another language, such as HTML, that a browser can understand.

Automate the Data Acquisition Process
The first challenge of this project was that it needed to be automated so there would be no need for programmer interaction to maintain the new datasets. In order to use the rapidly updated online SCEC catalogs automatically, it was necessary to explore the java.net interface that allows Java to communicate with a website by means of the Uniform Resource Locator (URL). The solution to this difficulty was to write a Java servlet that automatically called another java program each time the servlet was accessed via a web browser. The java program accesses the SCEC site, parses the HTML and converts the earthquake information into XML. The calling servlet is then able to apply an XSLT stylesheet to the XML data and render the result as a web page, the Earthquake List.

Explore Online Mapping Tools
The next step was to implement the mapping solution. This required researching online mapping tools to find a dynamic map site that suited the needs of this project. The selected website was the US Census bureau Tiger Map Server. This mapping engine was ideal because it provided public domain maps and the server could receive longitude and latitude parameters. Another servlet was created that requests a map, saves the map image to SDSU EdCenter server and then uploads the map in a Java Applet that is embedded within an HTML page.

Gather Demographic Information
In order to complete the mapping process, it was necessary to gather demographic data from the US Geological Survey. Required information included the longitude and latitude locations of hospitals, bridges, airports and tunnels within California. After this information was attained, a XML DTD was developed and a java program was used to convert the data into XML for use in the mapping tool. The mapping servlet then uses this XML data to determine what features are going to be drawn on the map by using another XSLT stylesheet to query the data. The feature data that meets specified criteria is passed to the applet and the applet overlays the hospitals, bridges, airports, and tunnels on the map. The applet also provides a feature that allows the user to click on any visible feature and the feature will be identified in a box below.

Civil Visualization
Integration and visualization of geophysical and demographical data for pro-active pre-emptive legislative crisis management and rapid emergency response

Ways of providing a more meaningful spatial context within which crisis management decision makers may interact with these complex datasets was also explored. Scripps Institute of Oceanography provided the opportunity to use Fledermaus, a scientific visualization program that is specifically designed to quickly and easily integrate and render massive amounts of 3D geophysical data and allow the user to interact with the data in realtime. Figures ??-?? show examples of images rendered with Fledermaus. Hopefully 3D imagery and movies will allow decision makers the ability to easily correlate locations of major seismic activity with large population centers and see demographic details that offer more rapid identification of appropriate emergency response measures.

Results and Conclusion

This prototype has the ability to help coordinate interactions with partners in science, engineering, risk management, government and business, as listed in the CEO long-range plan. It demonstrates one possible way of transparently transferring data in near-real time. It provides a useful product for professionals, supports improved hazard and risk management, and promotes public awareness.

Acknowledgements

SDSU EdCenter on Computation Science and Engineering
Jeff Sale
Kirsten Barber
http://www.edcenter.sdsu.edu

US Geological Survey
http://geonames.usgs.gov/pls/gnis/web_query.gnis_web_query_form

US Census Bureau TIGER/Line data
http://tiger.census.gov/cgi-bin/mapsurfer

Scripps Institute of Oceanography Visualization Center
Dr. Debra Kilb
http://www.siovizcenter.ucsd.edu

Figures

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