Summary & Purpose

We characterize and interpret a new type of infrasound signal originating from the summit of Volcán Cotopaxi (Ecuador) that was primarily observed between September 2015 and March 2016, following the 2015 eruptive period. This infrasound waveform is a slowly decaying sinusoid with exceptional low frequency (fp = 0.2 Hz) and high quality factor (Q=~10) and resembles the shape of tornillo seismic waveforms. The repeating events, occurring about once per day in early 2016, are stable in frequency content and we attribute them to excitation of a vertical-walled crater, with radius of about 125 m and length of 300 m. Spectral properties of the tornillo also permit constraints on crater sound speed (335-402 m/s) and temperature (4-167C). The initial polarity of the tornillos is predominantly a rarefaction and could reflect repeating crater bottom collapse events (implosions) or explosion sources whose infrasound is heavily modulated by the crater’s pipe-like geometry.

Date of Publication or Submission

4-23-2018

DOI

https://doi.org/10.18122/infrasound_data/2/boisestate

Funding Citation

National Science Foundation Grant EAR-0838562

Single Dataset or Series?

Series

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Creative Commons License This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

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