WORLDWIDE EARTHQUAKES RECORDED BY ASI, EQ1, AND GURLAP SEISMOGRAPHS

Each year the ASI, EQI, and Gurlap EDU inexpensive seismographs record numerous worldwide earthquakes. Last year, 2012, 70 earthquakes were recorded that arouse student interest in seismology. The seismograms of the earthquakes provide useful teaching materials and are used to write exercises for student use in the classroom. This poster will present many records of the earthquakes recorded during the past year and exercises on how they are used in seismology and introductory geology courses.

The seismographs usually detect earthquakes of magnitude 5 or greater. Computer software that accompanies the seismograph enables students to determine distance, identify phases, and compute the magnitude of the earthquakes. A Fourier Transform of the earthquake is also calculated by the software and is used to determine cutoff frequency and determine the source parameter including stress drop, moment and moment magnitude, and source radius.

The seismographs are also useful for teaching students how seismographs work. Undergraduates can install them in a short time and develop an understanding of how earthquakes are detected. The simplicity of the installation and use of the software makes possible the use of the seismographs on all levels. Information about the earthquakes recorded is available from IRIS Teachable Moments, which helps students understand worldwide seismicity and earthquake hazards.

The Gurlap Seismograph is a three-component system that produces useful seismograms for locating epicenters. The first motion of the seismographs are used to locate the epicenter by using the back azimuth method. The Gurlap is also portable and lightweight so it is possible to deploy it in the field.