Preprints
Filtering by Subject: Geophysics and Seismology
The sensitivity of lowermost mantle anisotropy to past mantle convection
Published: 2024-06-20
Subjects: Geophysics and Seismology, Mineral Physics
It is widely believed that seismic anisotropy in the lowermost mantle is caused by the flow-induced alignment of anisotropic crystals such as post-perovskite. What is unclear, however, is whether the anisotropy observations in the lowermost mantle hold information about past mantle flow, or if they only inform us about the present-day flow field. To investigate this, we compare the general and [...]
Predictive modelling of seismic properties in single-foliated slates
Published: 2024-06-17
Subjects: Earth Sciences, Geophysics and Seismology
Slates play a key role in understanding the seismic anisotropy of the continental crust, a crucial aspect of geophysical interpretation. Using a comprehensive set of high-quality single-foliated roofing slates, we determined their typical seismic properties via mineral fractions and orientation distribution functions using the VRH averaging method. Our study focused on identifying optimal polar [...]
Implementation of the Peruvian Earthquake Early Warning System
Published: 2024-06-12
Subjects: Artificial Intelligence and Robotics, Geophysics and Seismology
We present the implementation and testing of the seismological components of the Peruvian Earthquake Early Warning System (Sistema de Alerta Sísmica Peruano, SASPe). SASPe is designed to send alert messages to areas located within a given distance from the epicenter of large (magnitude ≥ 6.0) subduction earthquakes, with a first alert based on data available 3 seconds after the arrival [...]
Investigating the Dynamic History of a Promontory Ice Rise using Radar Data
Published: 2024-06-08
Subjects: Geophysics and Seismology, Glaciology
Ice rises hold valuable records revealing the ice dynamics and climatic history of Antarctic coastal areas from the Last Glacial Maximum to today. This history is often reconstructed from isochrone radar stratigraphy and simulations focusing on Raymond arch evolution beneath the divides. However, this relies on complex ice-flow models where many parameters are unconstrained by observations. Our [...]
Do large earthquakes start with a precursory phase of slow slip?
Published: 2024-06-07
Subjects: Geophysics and Seismology
In a recent publication, we showed that a stack of all GPS time series recorded before Magnitude ≥ 7.0 earthquakes suggests that large earthquakes start with a precursory phase of accelerating slow slip (Bletery and Nocquet, 2023). While no peer-reviewed comment or publication has formally contradicted this result, informal discussion has emerged on various platforms. We present here the [...]
Ensemble Kalman, Adaptive Gaussian Mixture, and Particle Flow Filters for Optimized Earthquake Forecasting
Published: 2024-06-01
Subjects: Dynamical Systems, Geophysics and Seismology, Other Statistics and Probability
Probabilistic forecasts are regarded as the highest achievable goal when predicting earthquakes, but limited information on stress, strength, and governing parameters of the seismogenic sources affects their accuracy. Ensemble data-assimilation methods, such as the Ensemble Kalman Filter (EnKF), estimate these variables by combining physics-based models and observations.While the EnKF has [...]
Unique composition and evolutionary histories of low velocity mantle domains
Published: 2024-05-31
Subjects: Earth Sciences, Geophysics and Seismology, Other Earth Sciences, Physical Sciences and Mathematics
The two `large low velocity provinces' (LLVPs) are broad seismic wave speed anomalies in Earth's lower mantle beneath Africa and the Pacific Ocean. Recent research suggests they represent volumes that contain relatively dense subducted oceanic crust (SOC), but the distribution of recycled material within them is an open question. Using simulations of 3-D global-scale mantle circulation over the [...]
Ringing mountain ranges: Teleseismic signature of the interaction of high-frequency wavefields with near-source topography at the Degelen nuclear test site
Published: 2024-05-26
Subjects: Geophysics and Seismology
Over the last decade there has been an international effort to find methods to recover and digitize recordings from historical earthquakes and explosions that occurred during the 1950’s through to the 1980’s. Making these recordings accessible in digital format offers opportunities to study what signatures are encoded in the data, and to apply state-of-the-art techniques and methods to historical [...]
Predictable recovery rates in near-surface materials after earthquake damage
Published: 2024-05-23
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Earthquakes introduce transient mechanical damage in the subsurface, which causes postseismic hazards and can take years to recover. This observation has been linked to relaxation, a phenomenon observed in a wide class of materials after straining perturbations, but its duration after earthquake ground shaking has not been constrained. Here, we analyse the effects of two successive large [...]
Non-typical supershear rupture: fault heterogeneity and segmentation govern unilateral supershear and cascading multi-fault rupture in the 2021 Mw 7.4 Maduo Earthquake
Published: 2024-05-05
Subjects: Geophysics and Seismology
Previous geodetic and teleseismic observations of the 2021 Mw 7.4 Maduo earthquake imply surprising but difficult-to-constrain complexity, including rupture across multiple fault segments and supershear rupture. Here, we present an integrated analysis of multi-fault 3D dynamic rupture models, high-resolution optical correlation analysis, and joint optical-InSAR slip inversion. Our preferred [...]
An analysis of the dynamic range of Distributed Acoustic Sensing for Earthquake Early Warning
Published: 2024-04-27
Subjects: Geophysics and Seismology
Owing to its deployment and sensing characteristics, Distributed Acoustic Sensing (DAS) has been touted as a promising technology for low-cost and low-latency Earthquake Early Warning (EEW). While preliminary experiments conducted by several research groups have yielded encouraging results, it must be acknowledged that these EEW feasibility studies were performed only on low-magnitude events. [...]
The influence of a sub-lithospheric layer width on the partitioning of the induced mantle flow, surface motions and subduction dynamics
Published: 2024-04-17
Subjects: Geophysics and Seismology, Other Earth Sciences, Planetary Geology, Tectonics and Structure
The partitioning of the three-dimensional mantle flow into toroidal and poloidal components is a diagnostic element to characterise tectonics regimes, with both fields being substantially active and representative of the contemporary mode of mantle convection. The toroidal:poloidal ratio (T/P) affects several aspects of mantle circulation, including the sinking of the subducting lithosphere into [...]
Systematic Review of the Geothermal Potential in Colombia: Implications as an Alternative Energy Source
Published: 2024-04-16
Subjects: Earth Sciences, Geochemistry, Geology, Geophysics and Seismology, Physical Sciences and Mathematics
Through literature review and information processing, the current state of geothermal energy in Colombia, its limitations, possible future uses, environmental impact and the current legal framework were described and analyzed. Approximations were made regarding the sustainability of geothermal energy in the country and its implications. Some of the projects, studies, and research that have been [...]
Digitising sandbox experiments using open-source Structure-from-Motion/photogrammetry/Digital Image Correlation package MicMac
Published: 2024-04-15
Subjects: Geology, Geophysics and Seismology, Tectonics and Structure, Volcanology
Structure-from-Motion and photogrammetry have been implemented in sandbox models to monitor deformation of their surface. Various software packages are available, either open-source of commercial. Some commercial packages are intuitive press-button equipment; these can be very practical to use, but they can be very expensive and unaffordable for most academic laboratories. Another option is [...]
Rapid earthquake-tsunami modeling: The multi-event, multi-segment complexity of the 2024 Mw 7.5 Noto Peninsula Earthquake governs tsunami generation
Published: 2024-04-14
Subjects: Geophysics and Seismology
The January 1st, 2024, moment magnitude (Mw) 7.5 Noto Peninsula earthquake ruptured in complex ways, challenging timely analysis of the tsunami generation. We present rapid and accurate tsunami models informed by a 6-subevent centroid moment tensor (CMT) model that we obtain by inverting teleseismic and strong motion data and validation against geodetic observations. We identify two distinct [...]