Online Near-Real-Time Seismic System for the Classroom

Journal of Geoscience Education, Mar 2004 by Gerencher, Joseph J Jr, Sands, Michael J

ABSTRACT

A software system, named Seismic Internet Monitoring Application (SIMA), has been developed to allow near-real-time display and evaluation of seismic traces via the Internet. SIMA consists of three components: an embedded microsystem which connects directly to the seismometer amplifier; a network-enabled server that locally displays and records the data while broadcasting over the Internet; and a client software application that allows for remote display, evaluation, and storage/retrieval of seismic data. Because the embedded microsystem can broadcast as many as four seismometers, and because the local server can connect to an arbitrary number of embedded microsystems, the user can simultaneously display signals from an arbitrary number of seismometers. Presently, seismic signals are available from two institutions to demonstrate the functionality of the system. all SIMA software components are available for downloading from www.physics.moravian.edu/seismic. Any classroom or person with an Internet connection can receive the seismic signals in near-real-time by downloading and running the SIMA client software on a computer that runs any version of Windows from 95 through XP. Classrooms connected to three or more servers can use the signals to locate earthquake epicenters. The system is free and available, and will be further developed to support additional educational applications.

INTRODUCTION

Students in the introductory Earth Science courses at Moravian College have been fascinated with the real-time seismic traces of our homemade seismic system, which has been in continuous operation for more than twelve years. Traces from our four long-period seismometers are continuously displayed in real-time on a television in front of the Earth Science classroom. This system has allowed us to view and record many earthquakes, some originating on the opposite side of the earth. However, output from this system has been limited to our classroom or, at most, our local building. When earthquakes are detected, the data are saved by an Apple lie microcomputer and are subsequently printed as seismograms.

The printed seismograms are typically duplicated for distribution to students and, by mail, to colleagues at other institutions who possess similar seismometers. The mail delay and the variation in appearance from institution to institution has limited their effective use in the classroom. Yet, for these many years, we have been pleased with our system and its performance, and have been glad to share our successes, via these analog representations, with students, friends, and interested colleagues. To further exploit the educational potentialities of our seismic equipment we needed to develop a better way to acquire, process, and distribute the seismic data. The immediacy of the Internet and its ubiquitous presence in science classrooms presented a compelling opportunity.

DISCUSSION

A three-axis, long-period seismograph system, using homemade horizontal seismometers of the Lehman design (Lehman, 1977), and a borrowed long-period vertical seismometer, have been running at Moravian College since 1990. The seismometer traces of all four seismometers appear in real-time on a television screen located at the front of the Earth Science classroom (Gerencher and Jackson, 1991). The three orthogonal long-period seismometers are maintained in the basement of the science building immediately beneath the classroom, and an identical horizontal seismometer, redundant in orientation with one of the basement units, is located within a Plexiglas case at the rear of the classroom. Students in the room can observe both the operation of this seismometer and how their movements disturb its trace on the television screen. all horizontal seismometers are adjusted to have a period of 18 seconds, whereas the vertical seismometer has a shorter period. The four seismic signals are evaluated, displayed, and, if seismic events are detected, stored on the floppy disk of an Apple He computer by means of a Srogram that was written expressly for this purpose ackson and Gerencher, 1991). Student interest in the dynamic nature of the system and on records of natural earthquakes has been consistently high, but further development of the system has been limited by the vintage computing equipment. Certain hardware components upon which this software system relies are no longer manufactured; indeed, they have ceased appearing even on the used computer equipment market.

Although student interest in the real-time traces has been high even when there is no seismic activity, students particularly enjoy those times when they are in the classroom as a seismic event is received. For these occasions, a surveyor's pendulum is hung within a vertical, eight-foot tall Plexiglas case that is mounted to the wall in the front of the classroom so students can try to view the unamplified motions of the room relative to the pendulum as the waves are propagating through our site. Most seismic events, however, arrive when the room is unoccupied, so students are supplied with a copy of the printed seismogram during the next class period. Contact the web site, www.physics.moravian.edu/seismic, for photographs of the room setup, construction details of the seismometers and the pendulum, example system output, a schematic diagram of the amplifier circuit, and an illustrated description of the history and development of this system.