Repeating earthquakes cluster at the edges of the afterslip in the aftermath of the 16th April 2016 M7.8 Pedernales earthquake in Ecuador - Archive ouverte HAL Accéder directement au contenu
Communication Dans Un Congrès Année : 2021

Repeating earthquakes cluster at the edges of the afterslip in the aftermath of the 16th April 2016 M7.8 Pedernales earthquake in Ecuador

Caroline Chalumeau
Hans Agurto-Detzel
  • Fonction : Auteur
Louis de Barros
Philippe Charvis
Audrey Galve
Stephen Hernandez
  • Fonction : Auteur
Yvonne Font
Mariah C. Hoskins
  • Fonction : Auteur
Jean-Mathieu Nocquet
Marc Regnier
  • Fonction : Auteur
Sandro Vaca
  • Fonction : Auteur
Monica Segovia
  • Fonction : Auteur

Résumé

The study of repeating earthquakes can provide us with a deeper understanding of the interaction between seismic and aseismic slip. Repeating earthquakes are the result of repeated loading and failure of single fault asperities, likely driven by surrounding aseismic slip. As such, they are especially useful in the study of transient or stable slow slip, such as afterslip, and can provide information on slip properties and fault mechanics, with possible applications to earthquake triggering, loading rates and earthquake forecasting. Off the coast of Ecuador, seismicity during both the inter-seismic and post-seismic periods has been previously linked to aseismic slip. We analyze one year of aftershocks following the 16th April 2016 Mw 7.8 Pedernales earthquake to find repeating families, using data recorded by permanent and temporary seismological stations. We calculate waveform cross-correlation coefficients (CC) on all available catalogue events, which we use to sort events into preliminary families, using a minimum CC of 0.95. These events were then stacked and used to perform template-matching on the continuous data. In total, 376 earthquakes were classified into 62 families of 4 to 15 earthquakes, including 8 from the one-year period before the mainshock. We later relocated these earthquakes using a double-difference method, which confirmed that most of them did have overlapping sources. Finally, repeaters’ magnitudes and corner frequencies were determined within clusters using the spectral ratio method. With these we were able to calculate stress drop variations in time and space. Repeating earthquakes seem to concentrate largely around the areas of largest afterslip release, where afterslip gradient is the highest. We also find an increase in the recurrence time of repeating events with time after the mainshock, over the first year of the postseismic period, which highlights a possible timeframe for the afterslip’s deceleration. Our results suggest that while most repeating aftershocks are linked to afterslip release, the afterslip gradient may play a bigger role in determining their location than previously thought.

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Dates et versions

hal-03533003 , version 1 (18-01-2022)

Identifiants

  • HAL Id : hal-03533003 , version 1

Citer

Caroline Chalumeau, Hans Agurto-Detzel, Louis de Barros, Philippe Charvis, Audrey Galve, et al.. Repeating earthquakes cluster at the edges of the afterslip in the aftermath of the 16th April 2016 M7.8 Pedernales earthquake in Ecuador. American Geophysical Union Fall Meeting 2021, Dec 2021, New Orleans, United States. ⟨hal-03533003⟩
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