Preprints
Filtering by Subject: Geophysics and Seismology
Topography and the shallow slip deficit inference
Published: 2018-04-14
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Images of earthquake slip serve as the foundation for understanding the distribution of coseismic energy release, theories about rupture propagation, and fault mechanics. Geodetic slip images are inferred using elastic models that link surface observations to fault activity at depth. To date, almost all elastic models used for these common calculations [10, 14, 19, 23] include the assumption that [...]
Rapid mantle flow with power-law creep explains deformation after the 2011 Tohoku mega-quake
Published: 2018-04-11
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The deformation transient that follows large subduction zone earthquakes is thought to originate from the interaction of viscoelastic flow in the asthenospheric mantle and slip on the megathrust that are both accelerated by the sudden coseismic stress change. The surface deformation following the 2011 Mw 9.0 Tohoku earthquake provides some of the most comprehensive constraints on surface [...]
Constraints on North Anatolian Fault zone width in the crust and upper mantle from S-wave teleseismic tomography
Published: 2018-04-09
Subjects: Earth Sciences, Geophysics and Seismology, Life Sciences, Physical Sciences and Mathematics
We present high resolution S‐wave teleseismic tomography images of the western segment of the North Anatolian Fault (NAFZ) in Turkey using teleseismic data recorded during the deployment period of the DANA array. The array comprised 66 stations with a nominal station spacing of 7 km, thus permitting a horizontal and vertical resolution of approximately 15 km. We use the current S‐wave results [...]
Asthenosphere flow modulated by megathrust earthquake cycles
Published: 2018-04-04
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Subduction megathrusts develop the largest earthquakes, often close to large population centers. Understanding the dynamics of deformation at subduction zones is therefore important to better assess seismic hazards. Here, I develop consistent earthquake cycle simulations that incorporate localized and distributed deformation based on laboratory-derived constitutive laws by combining boundary and [...]
Time-dependent compaction as a mechanism for regular stick-slips
Published: 2018-03-27
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Owing to their destructive potential, earthquakes receive considerable attention from laboratory studies. In friction experiments, stick-slips are studied as the laboratory equivalent of natural earthquakes, and numerous attempts have been made to simulate stick-slips numerically using the Discrete Element Method (DEM). However, while laboratory stick-slips commonly exhibit regular stress drops [...]
Rheological transitions facilitate fault-spanning ruptures on seismically active and creeping faults
Published: 2018-03-27
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Physical Sciences and Mathematics
The apparent stochastic nature of earthquakes poses major challenges for earthquake forecasting attempts. Physical constraints on the seismogenic potential of major fault zones may aid in improving seismic hazard assessments, but the mechanics of earthquake nucleation and rupture are obscured by the complexity that faults display. In this work, we investigate the mechanisms behind giant [...]
Enhanced velocity based pore pressure prediction using lithofacies clustering: A case study from a reservoir with complex lithology in Dezful Embayment, SW Iran
Published: 2018-03-21
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The primary goal of this paper is to improve accuracy and reliability of the conventional Bowers and Tau methods in a reservoir with complex lithology. We demonstrate the capability of the proposed method through a case study in a reservoir in the Southwest of Iran. Velocity based pore pressure prediction methods are widely accepted as a routine technique in the petroleum industry. Despite recent [...]
Kinematics of the active West Andean fold-and-thrust belt (Central Chile): structure and long-term shortening rate
Published: 2018-03-19
Subjects: Earth Sciences, Geomorphology, Geophysics and Seismology, Physical Sciences and Mathematics, Tectonics and Structure
West-verging thrusts, synthetic with the Nazca - South America subduction interface, have been recently discovered at the western front of the Andes. At ~33°30’S, the active San Ramón fault stands as the most frontal of these west-verging structures, and represents a major earthquake threat for Santiago, capital city of Chile. Here we elaborate a detailed 3D structural map and a precise [...]
Paleomagnetic Biases Inferred from Numerical Dynamos and the Search for Geodynamo Evolution
Published: 2018-03-19
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The orientation and intensity of the paleomagnetic field is central to our understanding of the history of the Earth. The paleomagnetic signature of the singular most event, inner core nucleation, however, remains elusive. In this study we study numerical dynamo simulations from a paleomagnetic perspective to explore how long observations must be time-averaged to obtain stable virtual [...]
Slow-slip events in semi-brittle serpentinite fault zones
Published: 2018-03-14
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Slow-slip events are earthquake-like events only with much lower slip rates. While peak coseismic velocities can reach tens of meters per second, slow-slip is on the order of 1E-7 m/s and may last for days to weeks. Under the rate-and-state model of fault friction, slow-slip is produced only when the asperity size is commensurate with the critical nucleation size, a function of frictional [...]
Tracking Groundwater Levels using the Ambient Seismic Field
Published: 2018-02-27
Subjects: Earth Sciences, Geophysics and Seismology, Hydrology, Physical Sciences and Mathematics
Aquifers are vital groundwater reservoirs for residential, agricultural, and industrial activities worldwide. Tracking their state with high temporal and spatial resolution is critical for water resource management at the regional scale yet is rarely achieved from a single dataset. Here, we show that variations in groundwater levels can be mapped using perturbations in seismic velocity (dv/v). [...]
Probing earthquake dynamics through seismic radiated energy rate: illustration with the M7.8 2015 Nepal earthquake
Published: 2018-02-26
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Dynamic characterizations of earthquakes focus on whole-event representations, that is whether the total radiation of seismic waves is more or less energetic. Denolle et al (2015) and Yin et al. (2018) suggest to use the source spectrogram in order to analyze the radiation during the rupture itself. Here, we take a retrospective view on these studies to better establish the methodology of source [...]
Active deformation of Malawi Rift’s North Basin hinge zone modulated by reactivation of pre-existing Precambrian shear zone fabric
Published: 2018-02-19
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: 2018-01-28
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: 2018-01-28
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. [...]