EGU24-9961, updated on 08 Mar 2024
https://doi.org/10.5194/egusphere-egu24-9961
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Do earthquakes start with precursory slow aseismic slip?

Quentin Bletery1 and Jean-Mathieu Nocquet1,2
Quentin Bletery and Jean-Mathieu Nocquet
  • 1Université Côte d'Azur, IRD, CNRS, Observatoire de la Côte d'Azur, Géoazur, France
  • 2Université de Paris Cité, Institut de Physique du Globe de Paris, CNRS, France

The existence of an observable precursory phase of aseismic slip on the faults before large earthquakes has been debated for decades. We conducted a global search for short-term precursory slip in GPS data. We summed the displacements measured by 3026 high-rate (5-minutes sample) GPS time series—projected onto the displacements expected from precursory slip at the hypocenter—during 48 hours before 90 (moment magnitude ≥7) earthquakes. Our approach revealed a ≈2-hour-long exponential acceleration of slip before the ruptures, suggesting that large earthquakes do start with a precursory phase of slip acceleration. The results have since been questioned as being due to an unfortunate combination of common mode noise in GPS time series. We investigate this possibility along with complementary tests to quantify the likelihood of the proposed pre-slip and the common mode hypotheses.

How to cite: Bletery, Q. and Nocquet, J.-M.: Do earthquakes start with precursory slow aseismic slip?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9961, https://doi.org/10.5194/egusphere-egu24-9961, 2024.