Spectrograms: Visualizing How the Frequency of Seismic Waves Varies With Time

Alan Kafka
Weston Observatory
Department of Earth and Environmental Sciences, Boston College

These (very cool, and beautiful, I think) graphics are “spectrograms” of some of our recordings of the magnitude 4.7 earthquake that recently occurred in Oklahoma.

The seismograph in Texas is operated by Kristi Rasmusson Fink, and the seismographs in MA are operated by Weston Observatory. The data processing was done by Jay Pulli.

A spectrogram is a particular way of visualizing the vibrations present in a seismogram. It shows how the frequency of the motion varies over time, and how different frequencies of vibration appear at different times in the record. Yellow colors represent stronger signals, and blue colors represent weaker signals.