The rise and fall of periodic ‘drumbeat’ seismicity at Tungurahua volcano, Ecuador

Bell, Andrew F.; Hernández, Stephen; Gaunt, Elizabeth; Mothes, Patricia; Ruiz, Mario; Sierra, Daniel A.; Aguaiza, Santiago

doi:10.1016/j.epsl.2017.07.030

Cited by 33 publications

(49 citation statements)

References 46 publications

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“…The most striking feature of the 2OSS is the presence of repeating events with highly similar waveforms. This is a feature commonly observed on other active volcanoes such as Redoubt (Chouet, ), Stromboli (Martini et al, ), Mount St. Helens (Matoza et al, ; Matoza & Chouet, ), Campi Flegrei (Cusano et al, ), and Tungurahua (Bell et al, ). They have generally been related to volcanic degassing processes.…”

Section: Discussionmentioning

confidence: 69%

The 2016 Tenerife (Canary Islands) Long‐Period Seismic Swarm

et al. 2019

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On 2 October 2016, a significant seismic swarm of long‐period events was recorded on Tenerife (Canary Islands, Spain). The swarm lasted more than 5 hr and consisted of at least 766 detected events. We found a positive correlation between the amplitude of each event and the preceding interevent time together with a stability of the spectral properties and waveform similarity during most of the swarm duration. Toward the end of the swarm, individual events merged into a continuous tremor. These observations can be explained by postulating an unsteady transonic choked flow within a crack‐like conduit as a source mechanism for this swarm. The flow resulted from a sudden discharge of magmatic fluids from a pressurized reservoir into the hydrothermal system of Tenerife. The injected fluids reached the surface starting about 1 month after the swarm, as evidenced by the macroscopic increase in the diffuse CO2 emissions from the crater of Teide volcano. The lack of ground deformation and the absence of relevant seismicity at depths greater than 10 km exclude the ascent of a basaltic magma batch as a causative source mechanism. Instead, we hypothesize the sudden release of fluids accumulated at the top of a magma chamber as a possible mechanism. Another possibility is the injection of a small batch of mafic magma into a cooling magma chamber, triggering a convective mixing. Both cases imply the presence of a magma chamber at depths greater than 8.6 km. These results have important implications for the development of the volcano monitoring system of Tenerife.

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Section: Discussionmentioning

confidence: 69%

The 2016 Tenerife (Canary Islands) Long‐Period Seismic Swarm

et al. 2019

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“…Many earthquake waveforms are highly similar, indicating the repeated activation of fixed‐location sources (Figures a and b). Cross‐correlation analysis, using a two‐stage clustering method (Bell et al, ; Green & Neuberg, ; Rodgers et al, ) with cross‐correlation thresholds of 0.7 and 0.8, finds only one dominant family of earthquakes with highly correlated waveforms, suggesting repeated activation of a single source location, but where the source progressively evolves through time (either due to a small change in location or small change in source mechanism; Figures a–c). Earthquake interevent times are quasiperiodic, approximating a gamma distribution when the systematic rate increase is accounted for (Figure d), meaning that they are not independent.…”

Section: Resultsmentioning

confidence: 99%

“…Nine hundred sixty events were picked in 24 hr before the explosion, of which 427 were recorded in the unlocated IGEPN catalogue for Tungurahua. None of the earthquakes were of sufficiently high amplitude to be detected on the broader IGEPN seismic network, and so are no locations are available, although typical horizontal and vertical location uncertainties for LP earthquakes at Tungurahua are on the order of a few kilometers (Bell et al, ). As the earthquakes are only well recorded at RETU, they are likely to be located at shallow levels in the edifice, and most probably in or close to the conduit.…”

Section: Methodsmentioning

confidence: 99%

“…We define periodicity as the ratio between the mean and standard deviation of the interevent times (Bell et al, ). For earthquakes that are randomly distributed in time (i.e., a Poisson process), with average rate λ , the interevent times follow an exponential distribution with mean μ = 1/ λ and variance σ 2 = 1/ λ 2 .…”

Section: Methodsmentioning

confidence: 99%

“…For LPs at Tungurahua, suggested source mechanisms include gas depressurization (Molina, ), magma stick‐slip or failure (Neuberg et al, ), and coupled magma ascent and gas depressurization (Bell et al, ). The statistical properties of LPs often include a restricted range or “characteristic” distribution of magnitudes (Bell et al, ), repeating waveforms indicating multiple reactivation of a small number of source locations (Green & Neuberg, ), and periodic (anticlustered) interevent times, sometimes referred to as “drumbeat” earthquakes (Bell et al, ; Iverson et al, ; White et al, ). Although accelerating rates of LPs have been reported before eruptions at several volcanoes (Boué et al, ; Neuberg et al, ; Salvage & Neuberg, ), it is not clear if these characteristics are consistent with the physics of a material failure process, and how such data and their patterns may be best used for forecasting.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Volcanic Eruption Forecasts From Accelerating Rates of Drumbeat Long‐Period Earthquakes

Bell

Naylor

Hernández

et al. 2018

Geophysical Research Letters

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Accelerating rates of quasiperiodic “drumbeat” long‐period earthquakes (LPs) are commonly reported before eruptions at andesite and dacite volcanoes, and promise insights into the nature of fundamental preeruptive processes and improved eruption forecasts. Here we apply a new Bayesian Markov chain Monte Carlo gamma point process methodology to investigate an exceptionally well‐developed sequence of drumbeat LPs preceding a recent large vulcanian explosion at Tungurahua volcano, Ecuador. For more than 24 hr, LP rates increased according to the inverse power law trend predicted by material failure theory, and with a retrospectively forecast failure time that agrees with the eruption onset within error. LPs resulted from repeated activation of a single characteristic source driven by accelerating loading, rather than a distributed failure process, showing that similar precursory trends can emerge from quite different underlying physics. Nevertheless, such sequences have clear potential for improving forecasts of eruptions at Tungurahua and analogous volcanoes.

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Predictability of Landslide Timing From Quasi‐Periodic Precursory Earthquakes

Bell

2018

Geophysical Research Letters

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Accelerating rates of geophysical signals are observed before a range of material failure phenomena. They provide insights into the physical processes controlling failure and the basis for failure forecasts. However, examples of accelerating seismicity before landslides are rare, and their behavior and forecasting potential are largely unknown. Here I use a Bayesian methodology to apply a novel gamma point process model to investigate a sequence of quasiperiodic repeating earthquakes preceding a large landslide at Nuugaatsiaq in Greenland in June 2017. The evolution in earthquake rate is best explained by an inverse power law increase with time toward failure, as predicted by material failure theory. However, the commonly accepted power law exponent value of 1.0 is inconsistent with the data. Instead, the mean posterior value of 0.71 indicates a particularly rapid acceleration toward failure and suggests that only relatively short warning times may be possible for similar landslides in future.

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The rise and fall of periodic ‘drumbeat’ seismicity at Tungurahua volcano, Ecuador

Cited by 33 publications

References 46 publications

The 2016 Tenerife (Canary Islands) Long‐Period Seismic Swarm

The 2016 Tenerife (Canary Islands) Long‐Period Seismic Swarm

Volcanic Eruption Forecasts From Accelerating Rates of Drumbeat Long‐Period Earthquakes

Predictability of Landslide Timing From Quasi‐Periodic Precursory Earthquakes

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