Preprints
Filtering by Subject: Geophysics and Seismology
Compressibility of ferropericlase at high-temperature: evidence for the iron spin crossover in seismic tomography
Published: 2023-04-05
Subjects: Earth Sciences, Geophysics and Seismology, Mineral Physics
The iron spin crossover in ferropericlase, the second most abundant mineral in Earth’s lower mantle, causes changes in a range of physical properties, including seismic wave velocities. Understanding the effect of temperature on the spin crossover is essential to detect its signature in seismic observations and constrain its occurrence in the mantle. Here, we report the first experimental results [...]
The Spectrum of Fault Slip in Elastoplastic Fault Zones
Published: 2023-03-31
Subjects: Civil and Environmental Engineering, Geophysics and Seismology, Mechanical Engineering
Natural faults are typically surrounded by damage zones that exhibit inelastic material response. This study investigates the role of fault zone strength in modulating the spectrum of fault slip across different spatio-temporal scales. We carry out long-term simulations of seismic and aseismic slip for an elastoplastic spring slider model with rate-and-state friction as well as a continuum model [...]
Bayesian estimation of nonlinear centroid moment tensors using multiple seismic data sets
Published: 2023-03-27
Subjects: Earth Sciences, Geophysics and Seismology
Centroid moment tensor (CMT) parameters of earthquakes are routinely estimated to gain information on structures and regional tectonics. However, for small earthquakes (M<4), it is still challenging to determine CMTs due to the lack of high-quality waveform data. In this study, we propose to improve solutions for small earthquakes by incorporating multiple seismic data types in Bayesian joint [...]
Linking the core heat content to Earth's accretion history
Published: 2023-03-26
Subjects: Earth Sciences, Geochemistry, Geophysics and Seismology, Planetary Geochemistry, Planetary Geophysics and Seismology
In this study we use a parameterized model of differentiation in a magma ocean setting, in which the magma ocean depth evolves during accretion, to predict the composition of the primordial core. We couple this chemical model to a thermal evolution model of the accreting metal to estimate the Earth's core heat content at the end of its formation. We find geochemically consistent models. All these [...]
Can homogeneous nucleation resolve the inner core nucleation paradox?
Published: 2023-03-24
Subjects: Condensed Matter Physics, Earth Sciences, Geophysics and Seismology, Mineral Physics, Planetary Geophysics and Seismology, Planetary Mineral Physics
Continuous isolated noise sources induce repeating waves in the coda of ambient noise correlations
Published: 2023-03-17
Subjects: Geophysics and Seismology, Other Physics
Continuous excitation of isolated noise sources leads to repeating wave arrivals in cross correlations of ambient seismic noise, including throughout their coda. These waves propagate from the isolated sources. We observe this effect on correlation wavefields computed from two years of field data recorded at the Gräfenberg array in Germany and two master stations in Europe. Beamforming the [...]
Complex rupture evolution of the 2007 Martinique earthquake: a non-double-couple event in the Caribbean Sea
Published: 2023-03-14
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
A large non-double-couple component of a tectonic earthquake indicates that its rupture likely was complex and likely involved multiple faults. Detailed source models of such earthquakes can add to our understanding of earthquake source complexity. The 2007 Martinique earthquake in the Caribbean Sea is one of the largest recent earthquakes with a known large non-double-couple component. It was an [...]
Asperity-like (segmented) structure of the 6 February 2023 Turkish earthquakes
Published: 2023-03-10
Subjects: Geophysics and Seismology
Key to studies of the rupture process is the identification of its major segmentation into asperities. Common multi-parametric methods invert for a continuous slip distribution; they usually rely on a predefined fault position, nucleation point, planarity, smoothing, etc. Here we propose more flexible low-parametric inversions - multi-point seismic source models, and multi-patch GPS models. We [...]
Largest aftershock nucleation driven by afterslip during the 2014 Iquique sequence
Published: 2023-03-10
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Various earthquake models predict that aseismic slip modulates the seismic rupture process but actual observations of such seismic-aseismic interaction are scarce. We analyze seismic and aseismic processes during the 2014 Iquique earthquake sequence. High-rate Global Positioning System (GPS) displacements demonstrate that most of the early afterslip is located downdip of the M 8.1 mainshock and [...]
A method for the measurement of seismic attenuation in polar firn
Published: 2023-03-03
Subjects: Geophysics and Seismology, Glaciology
We present seismic measurements of the firn column at Korff Ice Rise, West Antarctica, including measurements of compressional- and shear-wave velocity and attenuation. We describe a modified spectral-ratio method of measuring the seismic quality factor (Q) based on analysis of diving waves, which enables us to characterise the attenuative structure of firn in greater detail than has previously [...]
Multi-scale rupture growth with alternating directions in a complex fault network during the 2023 south-eastern Türkiye and Syria earthquake doublet
Published: 2023-03-03
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
A devastating doublet of earthquakes with moment magnitude Mw 7.9 and Mw 7.6 earthquakes contiguously occurred in SE Türkiye near the NW border of Syria. Here we perform a potency-density tensor inversion to simultaneously estimate rupture evolution and fault geometry for the doublet. We find the initial Mw 7.9 earthquake involved discrete episodes of supershear rupture and back-rupture [...]
False positives are common in single-station template matching
Published: 2023-02-17
Subjects: Earth Sciences, Geophysics and Seismology, Planetary Geophysics and Seismology, Planetary Sciences
Template matching has become a cornerstone technique of observational seismology. By taking known events, and scanning them against a continuous record, new events smaller than the signal-to-noise ratio can be found, substantially improving the magnitude of completeness of earthquake catalogues. Template matching is normally used in an array setting, however as we move into the era of planetary [...]
Curated Pacific Northwest AI-ready Seismic Dataset
Published: 2023-02-16
Subjects: Geophysics and Seismology
The curation of seismic data sets is the cornerstone of seismological research and the starting point of machine-learning applications in seismology. We present a 21-year-long AI-ready data set of diverse seismic event parameters, instrumentation metadata, and waveforms, as curated by the Pacific Northwest Seismic Network and ourselves. We describe the earthquake catalog and the temporal [...]
Gas - escape features along the Trzebiatów Fault offshore Poland: evidence for a leaking petroleum system
Published: 2023-02-10
Subjects: Geophysics and Seismology, Tectonics and Structure
New 2D high resolution seismic and hydro-acoustic data demonstrate the presence of methane in the shallow sediments and its origin in the Pomeranian Bight, southern of the Baltic Sea area. Various shallow gas features were identified in the Gryfice block, along the inverted Trzebiatów fault zone, including chimneys, bright spots, acoustic blanking, pockmarks, and polarity reversal. Structural and [...]
PyRaysum: Software for Modeling Ray-theoretical Plane Body-wave Propagation in Dipping Anisotropic Media
Published: 2023-02-10
Subjects: Geophysics and Seismology, Numerical Analysis and Scientific Computing
This article introduces PyRaysum, a Python software for modeling ray-theoretical body-wave propagation in dipping and/or anisotropic layered media based on the popular Fortran code Raysum. We improve and expand upon Raysum in several ways: 1) we significantly reduce the overhead by avoiding input/output operations; 2) we implement automatic phase labeling to facilitate the interpretation of [...]