Preprints
Filtering by Subject: Physical Sciences and Mathematics
Smooth crustal velocity models cause a depletion of high-frequency ground motions on soil in 2-D dynamic rupture simulations
Published: 2021-02-04
Subjects: Physical Sciences and Mathematics
A depletion of high-frequency ground motions on soil sites has been observed in recent large earthquakes and is often attributed to the nonlinear soil response. Here we show that the reduced amplitudes of high-frequency horizontal-to-vertical spectral ratios on soil can also be caused by a smooth crustal velocity model with low shear wave velocities underneath soil sites. We calculate near-fault [...]
Audible acoustics from low-magnitude fluid-induced earthquakes in Finland
Published: 2021-02-04
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
Earthquakes are frequently accompanied by public reports of audible low-frequency noises. In 2018, public reports of booms or thunder-like noises were linked to induced earthquakes during a Engineered Geothermal System project in the Helsinki Metropolitan area. In response, two microphone arrays were deployed to record and study these acoustic signals while stimulation at the drill site [...]
Distilling the Mechanism for the Madden-Julian Oscillation into a Simple Translating Structure
Published: 2021-02-03
Subjects: Physical Sciences and Mathematics
This paper presents a minimal model of the Madden--Julian Oscillation (MJO), isolating a robust mechanism that leads to the observed characteristic pattern and eastward propagation. A localized heat source due to condensation at the equator leads to a Gill-like pattern in the geopotential, which in turn induces moisture convergence and further condensation. Over a wide range of parameters [...]
Post-2018 caldera collapse re-inflation uniquely constrains Kīlauea's magmatic system
Published: 2021-02-02
Subjects: Physical Sciences and Mathematics
From August 2018 to May 2019, Kīlauea’s summit exhibited unique, simultaneous, inflation and deflation, apparent in both GPS time series and Small Baseline Subset (SBAS) derived cumulative InSAR displacement maps. This deformation pattern provides clear evidence that Halema`uma`u (HMM) and South Caldera (SC) are distinct reservoirs. Post-collapse inflation of the East Rift Zone (ERZ), as captured [...]
Dynamical attribution of North Atlantic interdecadal predictability to oceanic and atmospheric turbulence under realistic and optimal stochastic forcing
Published: 2021-02-01
Subjects: Climate, Environmental Sciences, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
Unpredictable variations in the ocean originate from both external atmospheric forcing and chaotic processes internal to the ocean itself, and are a crucial sink of predictability on interdecadal timescales. In a global ocean model, we present i.) an optimisation framework to compute the most efficient noise patterns to generate uncertainty and ii.) a uniquely inexpensive, dynamical method for [...]
Temperature and water depth effects on brGDGT distributions in sub-alpine lakes of mid-latitude North America
Published: 2021-02-01
Subjects: Earth Sciences, Environmental Sciences, Physical Sciences and Mathematics
Branched glycerol dialkyl glycerol tetraethers (brGDGTs) in lake sediments are increasingly being used to reconstruct past temperatures. However, recent studies suggest that brGDGT distributions and concentrations vary with lake size and environmental conditions such as seasonality and its effects on water column temperature and chemistry. To test their use as a paleothermometer in high-altitude [...]
Shear wave velocity structure beneath North-Western Himalaya and adjoining areas
Published: 2021-01-30
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure
Shear wave velocity structure, together with Moho depths have been estimated in northwestern Himalaya, Hindu Kush and the Pamirs at a potential resolution of 0.5×0.5 degrees and at 1×1 degrees in the surrounding area, by inverting fundamental mode Rayleigh wave group velocities calculated from regional earthquake (Δ ≤ 2500 km) data, and also from their joint inversions with teleseismic receiver [...]
Rift Interaction Zones and the Stages of Rift Linkage in Active Segmented Continental Rift Systems
Published: 2021-01-30
Subjects: Physical Sciences and Mathematics
Although much is known about the interaction of faulting and sedimentation within the basins of active segmented continental rift systems, little is known about these processes within the interaction zones of varying geometries that separate the young interacting segments. We address this problem in the humid, magma-poor juvenile western branch of the East African Rift System (WB-EARS). First, we [...]
Preliminary assessment of shipping noise monitoring using Distributed Acoustic Sensing on an optical fiber telecom cable
Published: 2021-01-30
Subjects: Physical Sciences and Mathematics
Distributed acoustic sensing (DAS) is a recent instrumental approach allowing to turn fiber-optic cables into dense arrays of acoustic sensors. This technology is attractive in marine environments where instrumentation is difficult to implement. A promising application is the monitoring of environmental and anthropic noise, leveraging existing telecommunication cables on the seafloor. We assess [...]
Was the January 26th, 1700 Cascadia earthquake part of an event sequence?
Published: 2021-01-30
Subjects: Physical Sciences and Mathematics
Coastal subsidence, dating of soil samples and tree rings, and sedimentological evidence of a tsunami point to coseismic activity on a sizable portion of the Cascadia subduction zone circa 1700. Documents from Japan reveal that on January 26th of that year there were tsunami impacts across distant locations in the country and past modeling shows that a large Cascadia earthquake is the most likely [...]
Upper Mississippi River Flow and Sediment Characteristics and Their Effect on a Harbor Siltation Case
Published: 2021-01-29
Subjects: Civil and Environmental Engineering, Civil Engineering, Earth Sciences, Engineering, Geomorphology, Hydraulic Engineering, Physical Sciences and Mathematics, Sedimentology
Upper Mississippi River flow and sediment characteristics downstream of St. Louis are presented in this study. Available and measured data were used to assess a harbor siltation case and dredging needs. Such data are also useful to researchers and engineers conducting work in the Mississippi River and large rivers in general. Flows were characterized in terms of the mean annual hydrograph, flow [...]
Goal-Oriented Error Estimation and Mesh Adaptation for Tracer Transport Modelling
Published: 2021-01-29
Subjects: Physical Sciences and Mathematics
This paper applies metric-based mesh adaptation methods to advection-dominated tracer transport modelling problems in two and three dimensions, using the finite element package Firedrake. In particular, the mesh adaptation methods considered are built upon goal-oriented estimates for the error incurred in evaluating a diagnostic quantity of interest (QoI). In the motivating example of modelling [...]
Tectonic evolution of an Early Cryogenian late-magmatic basin in central Madagascar
Published: 2021-01-29
Subjects: Earth Sciences, Physical Sciences and Mathematics
Central and southern Madagascar comprise a number of distinctive Archaean crustal blocks (the Antongil-Masora and Antananarivo domains) overlain by Proterozoic supracrustal sequences, preserved in the East African Orogen. Here, we present U–Pb and Lu–Hf isotopic data for two supracrustal units from detrital and metamorphic zircon grains. The lower sequence is comprised of quartzite and [...]
Back-propagating rupture evolution within a curved slab during the 2019 Mw 8.0 Peru intraslab earthquake
Published: 2021-01-29
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics
The 26 May 2019 Mw 8.0 Peru intraslab earthquake ruptured the subducting Nazca plate where the dip angle of the slab increases sharply and the strike angle rotates clockwise from the epicentre to north. To obtain a detailed seismic source model of the 2019 Peru earthquake, including not only the rupture evolution but also the spatiotemporal distribution of focal mechanisms, we performed [...]
The active and passive roles of the ocean in generating basin-scale heat content variability
Published: 2021-01-29
Subjects: Climate, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics
The role of ocean circulation in transforming surface forcing into interannual-to-multidecadal oceanic variability is an area of ongoing debate. Here, a novel method, establishing exact causal links, is used to quantitatively determine the role of ocean active and passive processes in transforming stochastic surface forcing into heat content variability. To this end, we use a global ocean model [...]