Forensic Seismology -- New Mexico Pipeline Accident

Seismographs are sensitive to general disturbances in the Earth and often record sonic or subsonic signals in the atmosphere as well. The study of seismograms from crime scenes or tragic accidents is called forensic seismology. (click images to view at full size)

During a deployment of IRIS PASSCAL (www.passcal.nmt.edu) seismographs in 2000 (www.ees.nmt.edu/Geop/Ristra/ristra.html), a natural gas pipeline explosion was recorded at distances as close as 19 km and as far as 136 km. This tragic incident was the deadliest pipeline explosion in the U.S. in 25 years, resulting in 12 deaths. The photo shows the crater created by the pipeline explosion. The seismic data from the explosion are a complex record of the coupled seismic and acoustic signals generated by the rupture, ignition, and ensuing fireball. These seismograms constrain the precise timing of the rupture to within several seconds, show that the initial rupture/ignition proceeded in three steps, and record the progressive shutting down of the pipeline after approximately 1 hour. The prolonged fireball produced an unusual protracted signal through the turbulent excitation of sound waves that were trapped near the ground by an early morning temperature inversion. These sound waves coupled with the Earth to produce strong seismic signals picked up by the seismometers. For another illustration of forensic seismology, see the October 2002 Image of the Week.

After: Koper, Wallace, and Aster, Seismic Recordings of the Carlsbad, new Mexico Pipeline Explosion of 19 August, 2000, Bulletin of the Seismological Society of America, in press, 2003.