Preprints
Filtering by Subject: Earth Sciences
The Last Glacial Maximum Balearic Abyssal Plain Megabed revisited
Published: 2020-03-18
Subjects: Earth Sciences, Physical Sciences and Mathematics, Sedimentology
Megabeds are thick sedimentary layers extending over thousands square kilometres in deep sea basins and are thought to result from large slope failures triggered by major external events. Such deposits have been found in at least three areas of the Mediterranean Sea. Although their discovery dates back to the early 1980s, many questions remain, concerning their initiation, source area, extent, [...]
Dynamic recrystallisation can produce porosity in shear zones
Published: 2020-03-18
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure
Creep cavities are increasingly recognised as an important syn-kinematic feature of shear zones but much about this porosity needs investigation. Largely, observations of creep cavities are restricted to very fine grained mature ultramylonites and it is unclear when they developed during deformation. Specifically, a question that needs testing is; should grain-size reduction during deformation [...]
Space-time stress variations on the Palu-Koro fault impacting the 2018 Mw 7.5 Palu earthquake and its seismic hazards
Published: 2020-03-09
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
In this study we calculated the Coulomb stress change before and after the 2018 Palu earthquake (Mw7.5) induced by historical large earthquakes on and around the Palu‐Koro fault (PKF) within Sulawesi Island, Indonesia. We found that the 1996 earthquake (Mw7.9) on the Minahassa thrust likely promoted the 2018 Palu earthquake by stress loading on its hypocenter. Stress shadows in the PKF impacted [...]
Improving the retrieval of offshore-onshore correlation functions with machine learning
Published: 2020-03-06
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The retrieval of reliable offshore-onshore correlation functions is critical to improve our ability to predict long-period ground motions from megathrust earthquakes. However, localized ambient seismic field sources between offshore and onshore stations can bias correlation functions and generate non-physical arrivals. We present a two-step method based on unsupervised learning to improve the [...]
Reply to “Global coastal wetland expansion under accelerated sea-level rise is unlikely”
Published: 2020-03-05
Subjects: Earth Sciences, Environmental Sciences, Physical Sciences and Mathematics, Sustainability
We thank Törnqvist et al. for engaging with our modelling study on the future response of global coastal wetlands to sea-level rise (SLR) and their careful and critical discussion of the presented methods and results. However, we disagree with their suggestion that our modelling approach is inadequate, a claim which relies on two arguments: (1) they argue that our results are inconsistent with [...]
On the formation of oceanic detachment faults and their influence on intra-oceanic subduction initiation: 3D thermomechanical modeling
Published: 2020-03-05
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
Extensional detachment faults, which have been widely documented in slow-spreading and ultraslow-spreading ridges on Earth, can effectively localize deformation due to their weakness. After the onset of oceanic closure, these weak oceanic detachments may directly control the nucleation of a subduction zone parallel to the former mid-ocean ridge, as is suggested for the Neotethys in Middle [...]
Global inventories of inverted stream channels on Earth and Mars
Published: 2020-03-04
Subjects: Earth Sciences, Geology, Geomorphology, Physical Sciences and Mathematics
Data from orbiting and landed spacecraft have provided vast amounts of information regarding fluvial and fluvial-related landforms and sediments on Mars. One variant of these landforms are sinuous ridges that have been interpreted to be remnant evidence for ancient fluvial activity, observed at hundreds of martian locales. In order to further understanding of these martian landforms, this paper [...]
Stress drop variation of deep-focus earthquakes based on empirical Greens function
Published: 2020-03-04
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
We analyze source characteristics of global, deep-focus (> 350 km) earthquakes with moment magnitudes (Mw) larger than 6.0-8.2 using teleseismic P-wave and S-wave spectra and an empirical Greens functions approach. We estimate the corner frequency assuming Brunes source model and calculate stress drops assuming a circular crack model. Based on P-wave and S-wave spectra, the one-standard [...]
Dynamic fault interaction during a fluid-injection induced earthquake: The 2017 Mw 5.5 Pohang event
Published: 2020-03-03
Subjects: Earth Sciences, Geophysics and Seismology, Life Sciences, Physical Sciences and Mathematics
The November 15th, 2017 Mw 5.5 Pohang earthquake (South Korea) has been linked to hydraulic stimulation and fluid injections, making this the largest induced seismic event associated with an Enhanced Geothermal System (EGS). To understand its source dynamics and fault interactions, we conduct the first 3D high-resolution spontaneous dynamic rupture simulations of an induced earthquake. We account [...]
Mechanistic insights into sulfur rich oil formation, relevant to geological carbon storage routes. A study using (+) APPI FTICR-MS analysis
Published: 2020-03-03
Subjects: Earth Sciences, Geochemistry, Physical Sciences and Mathematics
Sulfur incorporation into sedimentary organic matter has a key role in carbon preservation in the geosphere. Such processes can inform strategies for human timescale carbon storage to mitigate climate change impacts and thus more detailed knowledge of sulfur incorporation into biomass species is needed. Until recently, detailed chemical characterization of sulfurized organic matter was only [...]
Effect of fault damage zones on long-term earthquake behavior on mature strike-slip faults
Published: 2020-03-03
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Mature strike-slip faults are usually surrounded by a narrow zone of damaged rocks characterized by low seismic wave velocities. Observations of earthquakes along such faults indicate that seismicity is highly concentrated within this fault damage zone. However, the long-term influence of the fault damage zone on complete earthquake cycles, i.e., years to centuries, is not well understood. We [...]
Slip on wavy frictional faults: is the 3rd dimension a sticking point?
Published: 2020-03-03
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
The formulation for the 3D triangular displacement discontinuity boundary element method with frictional constraints is described in detail. Its accuracy in comparison to analytical solutions is then quantified. We show how this can be used to approximate stress intensity factors at the crack tips. Using this method, we go on to quantify how slip is reduced on fault surfaces with topography, [...]
Analytical prediction of seismicity rate due to tides and other oscillating stresses
Published: 2020-03-03
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Planetary Geophysics and Seismology, Planetary Sciences, Tectonics and Structure
Oscillatory stresses are ubiquitous on earth and other solid-surface bodies. Tides and seasonal signals perpetually stress faults in the crust. Relating seismicity to these stresses offers fundamental insight into earthquake triggering. We present a simple model that describes seismicity rate due to perpetual oscillatory stresses. The model applies to large amplitude, non-harmonic, and [...]
Integrated geotechnical, sedimentological and geophysical investigation of seafloor instabilities in the Gulf of Lions Western Mediterranean
Published: 2020-03-03
Subjects: Earth Sciences, Physical Sciences and Mathematics, Sedimentology
The Gulf of Lions presents recurring mass-transport deposits (MTDs) within the Plio-Quaternary sediments suggesting a long history of mass-movements. The two large, surficial MTDs are located on the eastern and western levee of the Rhone canyon over an area exceeding 6000 km2 and volumes exceeding 100 km3. Both MTDs were emplaced 21 ka ago (peak of the Last Glacial Maximum), suggesting a common [...]
Magma diversity reflects recharge regime and thermal structure of the crust
Published: 2020-03-03
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Volcanology
The chemistry of magmas erupted by volcanoes is a message from deep within the Earth’s crust, which if decrypted, can provide essential information on magmatic processes occurring at inaccessible depths. While some volcanoes are prone to erupt magmas of a wide compositional variety, others sample rather monotonous chemistries through time. Whether such differences are a consequence of physical [...]