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Recording Tragedy: The Seismic Signal of the Arecibo Radio Telescope Collapse

Session: Explosion Seismology Applications and Advances [Poster]

Type: Poster

Date: 4/19/2021

Presentation Time: 11:30 AM Pacific

Description: 

It has long been recognized that seismic stations record more than just earthquake signals and that those signals can be interpreted among these non-earthquake signals are mine blasts, nuclear tests, and storms. On December 1, 2020, the radio telescope at the Arecibo observatory tragically collapsed. The observatory however houses more scientific instrumentation including collocated 3 component broadband and strong motion instrumentation run by the Puerto Rico Seismic Network/Puerto Rico Strong Motion Program. The on-site instrument AOPR recorded the collapse in full. Coincidently, the collapse occurred during the end of a surface wave train from a regional earthquake located in the Dominican Republic. This earthquake “noise” while small amplitude relative to the collapse signal was nonetheless filtered out through the application of a high pass filter with a corner frequency of 3Hz. Seismic signals of the collapse initiated at 11:52:20 with a small amplitude vibrational signal with a marked increase of signal energy at 11:52:27.6 UTC and a further increase at 11:52:34 UTC. This can be interpreted as vibrations from the supporting structures as cables supporting the radio telescope failed in cascade. With the collapse signal two distinct impact signals are present at 11:52:38.4 UTC and 11:52:41.9 UTC. The latter impact signal is dominated by the shear wave which is indicative of a shear wave source. Here this is preliminarily interpreted as the impact of the instrument along the bedrock wall that contained the telescope as it swung into the wall. The first impact signal can be interpreted as either the vertical impact of the hub as it fell or the collapse of towers near the seismic instrument. Seismic signals from the collapse taper out by 11:52:54 UTC. This seismic record has the advantage in that it has accurate timings relative to other devices recording the collapse; combing the seismic signals presented here with video evidence can aid engineers in unravelling the sequence of this tragic event.

Presenting Author: Elizabeth A. Vanacore

Student Presenter: No

Authors