Preprints
Filtering by Subject: Geophysics and Seismology
Active deformation of Malawi Rift’s North Basin hinge zone modulated by reactivation of pre-existing Precambrian shear zone fabric
Published: 2018-02-20
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
Key Points: 1. Filtered aeromagnetic data elucidates the relationship between earthquake surface ruptures and buried faults along the North Basin hinge-zone, Malawi Rift. 2. Fault segments align with basement shear zone fabric. 3. Strain accommodation in the North Basin hinge zone is modulated by reactivation of the underlying Precambrian shear zone fabric. Abstract: We integrated temporal [...]
High Resolution, Millennial-Scale Patterns of Bed Compensation on a Sand-Rich Intraslope Submarine Fan, Western Niger Delta Slope
Published: 2018-01-29
Subjects: Earth Sciences, Geology, Geomorphology, Geophysics and Seismology, Other Earth Sciences, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Near-seafloor core and seismic-reflection data from the western Niger Delta continental slope document the facies, architecture, and evolution of submarine channel and intraslope submarine fan deposits. The submarine channel enters an 8 km long x 8 km wide intraslope basin, where more than 100 m of deposits form an intraslope submarine fan. Lobe deposits in the intraslope submarine fan show no [...]
Rapid Adjustment of Submarine Channel Architecture to Changes in Sediment Supply
Published: 2018-01-29
Subjects: Earth Sciences, Geology, Geomorphology, Geophysics and Seismology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Changes in sediment supply and caliber during the last ~130 ka have resulted in a complex architectural evolution of the Y channel system on the western Niger Delta slope. This evolution consists of four phases, each with documented or inferred changes in sediment supply. Phase 1 flows created wide (1,000 m), low-sinuosity (1.1) channel forms with lateral migration and little to no aggradation. [...]
Two Fundamentally Different Types of Submarine Canyons Along the Continental Margin of Equatorial Guinea
Published: 2018-01-25
Subjects: Earth Sciences, Geology, Geomorphology, Geophysics and Seismology, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Most submarine canyons are erosive conduits cut deeply into the world’s continental shelves through which sediment is transported from areas of high coastal sediment supply onto large submarine fans. However, many submarine canyons in areas of low sediment supply do not have associated submarine fans and show significantly different morphologies and depositional processes from those of ‘classic’ [...]
A consistent global approach for morphometric characterisation of subaqueous landslides
Published: 2018-01-12
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Life Sciences, Physical Sciences and Mathematics, Sedimentology, Stratigraphy
Landslides are common in aquatic settings worldwide, from lakes and coastal environments to the deep-sea. Fast-moving, large volume landslides can potentially trigger destructive tsunamis. Landslides damage and disrupt global communication links and other critical marine infrastructure. Landslide deposits act as foci for localised, but important deep-seafloor biological communities. Under burial, [...]
The spectrum of slip behaviours of a granular fault gouge analogue governed by rate and state friction.
Published: 2017-12-13
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The exact principles of earthquake recurrence and magnitude are currently unknown which is why earthquake hazard assessment relies on statistical models combined with numerical simulations. A component of seismic and aseismic slip is the frictional character of a fault. We shear fused glass beads with a narrow particle size distribution of 300-400µm at stresses of 5-20kPa and with low shear rates [...]
The Apparent Stratification at the Top of Earths Liquid Core
Published: 2017-12-11
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Earths magnetic field is generated by turbulent motion in its fluid outer core. Although the bulk of the outer core is vigorously convecting and well-mixed, some seismic, geomagnetic, and geodynamic evidence suggests that a global stably stratified layer exists at the top of Earths core. Such a layer would strongly influence thermal, chemical, and momentum exchange across the core-mantle boundary [...]
Synchronization of great subduction megathrust earthquakes: Insights from scale model analysis
Published: 2017-12-05
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The size of great subduction megathrust earthquakes is controlled mainly by the number of adjacent asperities failing synchronously and the resulting rupture length. Here we investigate experimentally the long-term recurrence behavior of a pair of asperities coupled by quasi-static stress transfer over hundreds of seismic cycles. We statistically analyze long (c. 500 ka) time-series of M8-9 [...]
The crisis of a paradigm. A methodological interpretation of Tohoku and Fukushima catastrophe
Published: 2017-12-04
Subjects: Earth Sciences, Environmental Studies, Geophysics and Seismology, Physical Sciences and Mathematics, Social and Behavioral Sciences, Tectonics and Structure
The 2011 Japanese disaster often presented as a ‘new Chernobyl’ accumulated the effects of earthquake, tsunami and of the subsequent nuclear accident at Fukushima. In the light of this disaster, we review methodological rea- sons both from geophysical and philosophical perspectives that lead the scientific and technological communities to flawed conclusions, prime cause of the disaster. The [...]
The role of coseismic Coulomb stress changes in shaping the hard-link between normal fault segments
Published: 2017-11-27
Subjects: Earth Sciences, Geology, Geomorphology, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
The mechanism and evolution of fault linkage is important in the growth and development of large faults. Here we investigate the role of coseismic stress changes in shaping the hard-links between parallel normal fault segments (or faults), by comparing numerical models of the Coulomb stress change from simulated earthquakes on two en echelon fault segments to natural observations of hard-linked [...]
Rupture Process during the Mw 8.1 2017 Chiapas Mexico Earthquake: Shallow Intraplate Normal Faulting by Slab Bending
Published: 2017-11-25
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
A seismic source model for the Mw 8.1 2017 Chiapas, Mexico, earthquake was constructed by kinematic waveform inversion using globally observed teleseismic waveforms, suggesting that the earthquake was a normal-faulting event on a steeply dipping plane, with the major slip concentrated around a relatively shallow depth of 28 km. The modeled rupture evolution showed unilateral, down-dip propagation [...]
Numerical solution of a non-linear conservation law applicable to the interior dynamics of partially molten planets
Published: 2017-11-21
Subjects: Applied Mathematics, Computer Sciences, Earth Sciences, Fluid Dynamics, Geophysics and Seismology, Numerical Analysis and Computation, Numerical Analysis and Scientific Computing, Physical Sciences and Mathematics, Physics
The energy balance of a partially molten rocky planet can be expressed as a non-linear diffusion equation using mixing length theory to quantify heat transport by both convection and mixing of the melt and solid phases. Crucially, in this formulation the effective or eddy diffusivity depends on the entropy gradient, dS/dr, as well as entropy itself. First we present a simplified model with [...]
Seismic and structural characterization of a pre-salt rifted section: the Lagoa Feia Group, Campos Basin, offshore Brazil
Published: 2017-11-18
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Stratigraphy
The exploration of pre-salt offshore SE Brazil presents a multifaceted deep-water scenario that is bringing new challenges to seismic interpretation in offshore Brazilian exploration and production. Reservoirs in this domain are complex, heterogeneous with layered carbonates which makes accurate reservoir characterization very challenging. Our study here deals with the seismic characterization of [...]
A new global mode of Earth deformation: seasonal cycle detected
Published: 2017-11-14
Subjects: Earth Sciences, Environmental Monitoring, Environmental Sciences, Geophysics and Seismology, Hydrology, Oceanography and Atmospheric Sciences and Meteorology, Other Earth Sciences, Other Environmental Sciences, Other Oceanography and Atmospheric Sciences and Meteorology, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics
We have detected a global mode of Earth deformation that is predicted by theory. Precise positioning of GPS sites distributed worldwide reveals that in February to March the northern hemisphere compresses (and the southern hemisphere expands), such that sites near the North Pole move downward by 3.0 mm, and sites near the equator are pulled northwards by 1.5 mm. The opposite pattern of [...]
Choice of optimal averaging radii for temporal GRACE gravity solutions, a comparison with GPS and satellite altimetry
Published: 2017-11-14
Subjects: Earth Sciences, Environmental Monitoring, Environmental Sciences, Geophysics and Seismology, Glaciology, Hydrology, Other Earth Sciences, Other Environmental Sciences, Physical Sciences and Mathematics
One of the initial challenges of the GRACE mission is to validate the accuracy of the time-variable gravity fields. These gravity fields contain both spatially correlated (systematic) and random noise and hence spatial averaging needs to be implemented. Before the fields may be interpreted, optimum averaging radii need to be determined through comparison with independent data. We compare time [...]