pinecone/core-2020-05-10-deduplication huggingface dataset:
Anisotropy in Fracking: A Percolation Model for Observed Microseismicity

Hydraulic fracturing (fracking) using high pressures and a low viscosity
fluid allow the extraction of large quantiles of oil and gas from very low
permeability shale formations. The initial production of oil and gas at depth
leads to high pressures and an extensive distribution of natural fractures
which reduce the pressures. With time these fractures heal, sealing the
remaining oil and gas in place. High volume fracking opens the healed fractures
allowing the oil and gas to flow the horizontal productions wells. We model the
injection process using invasion percolation. We utilize a 2D square lattice of
bonds to model the sealed natural fractures. The bonds are assigned random
strengths and the fluid, injected at a point, opens the weakest bond adjacent
to the growing cluster of opened bonds. Our model exhibits burst dynamics in
which the clusters extends rapidly into regions with weak bonds. We associate
these bursts with the microseismic activity generated by fracking injections. A
principal object of this paper is to study the role of anisotropic stress
distributions. Bonds in the $y$-direction are assigned higher random strengths
than bonds in the $x$-direction. We illustrate the spatial distribution of
clusters and the spatial distribution of bursts (small earthquakes) for several
degrees of anisotropy. The results are compared with observed distributions of
microseismicity in a fracking injection. Both our bursts and the observed
microseismicity satisfy Gutenberg-Richter frequency-size statistics.Comment: 14 pages, 10 figure
Detiding DART buoy data for real-time extraction of source coefficients
  for operational tsunami forecasting

U.S. Tsunami Warning Centers use real-time bottom pressure (BP) data
transmitted from a network of buoys deployed in the Pacific and Atlantic Oceans
to tune source coefficients of tsunami forecast models. For accurate
coefficients and therefore forecasts, tides at the buoys must be accounted for.
In this study, five methods for coefficient estimation are compared, each of
which accounts for tides differently. The first three subtract off a tidal
prediction based on (1) a localized harmonic analysis involving 29 days of data
immediately preceding the tsunami event, (2) 68 pre-existing harmonic
constituents specific to each buoy, and (3) an empirical orthogonal function
fit to the previous 25 hrs of data. Method (4) is a Kalman smoother that uses
method (1) as its input. These four methods estimate source coefficients after
detiding. Method (5) estimates the coefficients simultaneously with a
two-component harmonic model that accounts for the tides. The five methods are
evaluated using archived data from eleven DART buoys, to which selected
artificial tsunami signals are superimposed. These buoys represent a full range
of observed tidal conditions and background BP noise in the Pacific and
Atlantic, and the artificial signals have a variety of patterns and induce
varying signal-to-noise ratios. The root-mean-square errors (RMSEs) of least
squares estimates of sources coefficients using varying amounts of data are
used to compare the five detiding methods. The RMSE varies over two orders of
magnitude between detiding methods, generally decreasing in the order listed,
with method (5) yielding the most accurate estimate of source coefficient. The
RMSE is substantially reduced by waiting for the first full wave of the tsunami
signal to arrive. As a case study, the five method are compared using data
recorded from the devastating 2011 Japan tsunami.Comment: 20 pages; 3 tables; 15 figure
On the use of fractal surfaces to understand seismic wave propagation in layered basalt sequences.

The aim of this study is to better understand how a layered basalt sequence affects the propagation of a seismic wave, which has implications for sub-basalt seismic imaging. This is achieved by the construction of detailed, realistic models of basalt sequences, using data derived directly from outcrop analogues. Field data on the surface roughness of basaltic lava flows were captured using terrestrial laser scanning and satellite remote sensing. The fractal properties of the surface roughness were derived, and it can be shown that the lava flow surface is fractal over length scales up to approximately 2 km. The fractal properties were then used to construct synthetic lava flow surfaces using a von Karman power spectrum, and the resulting surfaces were then stacked to create a synthetic lava flow sequence. P-wave velocity data were then added, and the resulting model was used to generate synthetic seismic data. The resulting stacked section shows that the ability to resolve the internal structure of the lava flows is quickly lost due to scattering and attenuation by the basalt pile. A further result from generating wide-angle data is that the appearance of a lower-velocity layer below the basalt sequence may be caused by destructive interference within the basalt itself
A Threshold-Based Earthquake Early-Warning System for Offshore Events in Southern Iberia

The south of the Iberian Peninsula is a region situated at the convergence of the Eurasian and African plates. This region experiences large earthquakes with a long separation in time, the best known of which is the great 1755 Lisbon Earthquake (i.e., maximum macroseismic intensity, Imax=X), which occurred SW of San Vicente Cape (SW Iberian Peninsula). The high risk of damaging earthquakes has recently lead Carranza et al. (2013) to investigate the feasibility of an EEWS in this region. The analysis of the geometrical situation between the Iberian seismic networks and the San Vicente Cape area led the authors to conclude that a threshold-based approach, which would not require the real-time location of the earthquake, might be the best option for EEWS in SW Iberia. The current work explores this hypothesis, and proposes a new EEW approach that extends the standard P-wave threshold based single station analysis to the whole network. The proposed method allows the real-time estimation of the potential damage at stations that are triggered by P-waves, as well as at the not-triggered ones, giving the advantage of a greater lead-time for the release of alerts. Results of tests made with synthetic data mimicking the scenario of the great 1755 Lisbon Earthquake, and those obtained by applying the new approach to available recordings, indicate that an EEW estimation of the potential damage associated with an event in the San Vicente Cape area can be obtained for a very large portion of the Iberian Peninsula
P-wave velocity, density and vertical stress magnitude along the crustal Po Plain (northern Italy) from sonic log drilling data

In order to better characterize P-wave velocities for the shallow crust of the Po Plain
and surrounding regions, we have selected 64 deep wells mainly located in the plain
and also along the Apennine belt and Adriatic coast. In particular, we have analyzed
the stratigraphic profiles for all wells, and the available sonic logs (37 out of 64).
From these data we have examinated the P-wave velocity trend with depth and
estimated rock density following an empirical relationship between sonic velocity and
density in sedimentary rocks. Then we have calculated, notably for the first time in a
large area of Italy, the overburden stress magnitude for each well. For instance at a
depth of 5 km we have found values varying from 105 to 130 MPa moving from the
Adriatic coast to the Apennine belt. Consequently, the Apennines belt shows a
maximum regional lithostatic gradient of around 26 MPa/km while the Po Plain and
Adriatic region have values of around 21 MPa/km. The maximum density value that
can be considered for the Apennine crustal belt corresponds to 2.65 g/cm3; in the Po
Plain the mean density is around 2.25 g/cm3, while in the Adriatic area the average
density has the lowest value in the region at 2.13 g/cm3. Although in this area a 2D
crustal P-wave velocity model does not adequately constrain the complicated and
uneven tectonics, we have nevertheless established a shallow model consisting of five
separate layers. The strength of this paper lies in the possible use of these direct data,
together with other derived geological and geophysical information, to build a 3D
model of the area
Ground-motion simulation in the Lower Tagus Valley Basin

Throughout history, the Lower Tagus Valley (LTV) region has been shaken by several earthquakes, including some with moderate to large magnitudes and with sources located inside the basin, for example the 1344 (M6.0) and 1909 (M6.0) earthquakes. Previous simulations (Bezzeghoud et al. Natural Hazard 69: 
1229–1245, 2011) have revealed strong amplification of the amplitude waves in the region, because of the effect of the low-velocity sediments that fill the basin. The model used in those simulations was updated in this work by including new high-resolution geophysical and geotechnical data available for the area (seismic reflection, aeromagnetic, gravimetric, deep wells, standard penetration tests, and geological data). To contribute to improved assessment of seismic hazard in the LTV, we simulated propagation of seismic waves produced by moderate earthquakes in a 3D heterogeneous medium by using elastic finite-difference wave propagation code. The method, successfully used by Grandin et al. (Geophys J Int 171: 1144–1161, 2007), involves evaluation of the seismic potential of known faults in the area studied and three-dimensional seismic ground motion modelling by use of finite difference methods. On the basis of this methodology, we calculated the ground motion for the April 23, 1909, Benavente (Portugal) earthquake (Mw = 6.0) in dense grid points, then computed the synthetic isoseismic map of the area by use of appropriate relationships between seismic intensity (MMI) and peak ground velocity (PGV). The synthetic results, in contrast with available macroseismic and instrumental data, enable validation of the source models proposed for the area, identification of the 
sources of historical earthquakes, and could also indicate which areas are more exposed to seismic ground motion
Ekman spiral in horizontally inhomogeneous ocean with varying eddy viscosity

The article of record as published may be found at http://dx.doi.org/10.1007/s00024-015-1063-4Classical Ekman spiral is generated by surface wind stress with constant eddy viscosity in
homogeneous ocean. In real oceans, the eddy viscosity varies due to turbulent mixing caused by 
surface wind and buoyancy forcing. Horizontally inhomogeneous density produces vertical geostrophic 
shear which contributes to current shear that also affects the Ekman spiral. Based on the similar 
theoretical framework as the classical Ekman spiral, the baroclinic components of the Ekman spiral 
caused by the horizontally inhomogeneous density are obtained analytically with the varying eddy 
viscosity calculated from surface wind and buoyancy forcing using the K- Profile Parameterization 
(KPP). Along with the three existing types of eddy viscosity due to pure wind forcing (zero surface 
buoyancy flux), such an effect is evaluated using the climatological monthly mean data of surface 
wind stress, buoyancy flux, ocean temperature and salinity, and mixed layer depth
A user-oriented methodology for DInSAR time series analysis and interpretation: landslides and subsidence case studies

Recent advances in multi-temporal Differential Synthetic Aperture Radar (SAR) Interferometry (DInSAR) have greatly improved our capability to monitor geological processes. Ground motion studies using DInSAR require both the availability of good quality input data and rigorous approaches to exploit the retrieved Time Series (TS) at their full potential. In this work we present a methodology for DInSAR TS analysis, with particular focus on landslides and subsidence phenomena. The proposed methodology consists of three main steps: (1) pre-processing, i.e., assessment of a SAR Dataset Quality Index (SDQI) (2) post-processing, i.e., application of empirical/stochastic methods to improve the TS quality, and (3) trend analysis, i.e., comparative implementation of methodologies for automatic TS analysis. Tests were carried out on TS datasets retrieved from processing of SAR imagery acquired by different radar sensors (i.e., ERS-1/2 SAR, RADARSAT-1, ENVISAT ASAR, ALOS PALSAR, TerraSAR-X, COSMO-SkyMed) using advanced DInSAR techniques (i.e., SqueeSAR™, PSInSAR™, SPN and SBAS). The obtained values of SDQI are discussed against the technical parameters of each data stack (e.g., radar band, number of SAR scenes, temporal coverage, revisiting time), the retrieved coverage of the DInSAR results, and the constraints related to the characterization of the investigated geological processes. Empirical and stochastic approaches were used to demonstrate how the quality of the TS can be improved after the SAR processing, and examples are discussed to mitigate phase unwrapping errors, and remove regional trends, noise and anomalies. Performance assessment of recently developed methods of trend analysis (i.e., PS-Time, Deviation Index and velocity TS) was conducted on two selected study areas in Northern Italy affected by land subsidence and landslides. Results show that the automatic detection of motion trends enhances the interpretation of DInSAR data, since it provides an objective picture of the deformation behaviour recorded through TS and therefore contributes to the understanding of the on-going geological processes
Simulations of Tropical Circulation and Winter Precipitation Over North India: an Application of a Tropical Band Version of Regional Climate Model (RegT-Band)

This document is the Accepted Manuscript version of the following article: Tiwari, P.R., Kar, S.C., Mohanty, U.C. et al. Pure Appl. Geophys. (2016) 173: 657. https://doi.org/10.1007/s00024-015-1102-1. The final publication is available at Springer via: http://dx.doi.org/10.1007/s00024-015-1102-1. ?? Springer Basel 2015.In the present study, simulations have been carried out to study the relationship between winter-time precipitations and the large-scale global forcing (ENSO) using the tropical band version of Regional Climate Model (RegT-Band) for 5 El Nin??o and 4 La Nin??a years. The RegT-Band model is integrated with the observed sea-surface temperature and lateral boundary conditions from National Center for Environmental Prediction (NCEP)- Department of Energy (DOE) reanalysis 2 (NCEP-DOE2). The model domain extends from 50S to 50N and covers the entire tropics at a grid spacing of 45 km, i.e., it includes lateral boundary forcing only at the southern and northern boundaries. The performance evaluation of the model in capturing the large-scale fields followed by ENSO response with winter-time precipitation has been carried out by using model simulations against NCEP-DOE2 and Global Precipitation Climatology Project (GPCP) precipitation data. The analysis suggests that the model is able to reproduce the upper airfields and large-scale precipitation during winter time, although the model has some systematic biases compared to the observations. A comparison of model-simulated precipitation with observed precipitation at 17 station locations has been carried out. It is noticed that the RegT-Band model simulations are able to bring out the observed features reasonably well. Therefore, this preliminary study indicates that the tropical band version of the regional climate model can be effectively used for the better understanding of the large-scale global forcing
Modeling of Kashmir Aftershock Decay Based on Static Coulomb Stress Changes and Laboratory-Derived Rate-and-State Dependent Friction Law

We model the spatial and temporal evolution of October 8, 2005 Kashmir earthquake’s aftershock activity using the rate-and-state dependent friction model incorporating uncertainties in computed coseismic stress perturbations. We estimated the best possible value for frictional resistance ‘‘Arn’’, background seismicity rate ‘‘r’’ and coefﬁcient of stress variation ‘‘CV’’ using maximum log-likelihood method. For the whole Kashmir earthquake sequence, we measure a frictional resistance Arn * 0.0185 MPa, r * 20 M3.7? events/year and CV = 0.94 ± 0.01. The spatial and temporal forecasted seismicity rate of modeled aftershocks ﬁts well with the spatial and temporal distribution of observed aftershocks that occurred in the regions with positive static stress changes as well as in the apparent stress shadow region. To quantify the effect of secondary aftershock triggering, we have re-run the estimations for 100 stochastically declustered catalogs showing that the effect of aftershock-induced secondary stress changes is obviously minor compared to the overall uncertainties, and that the stress variability related to uncertain slip model inversions and receiver mechanisms remains the major factor to provide a reasonable data ﬁt
Tsunami penetration in tidal rivers, with observations of the Chile 2015
  tsunami in rivers in Japan

An extensive data set of water level measurements of the September 2015
Chilean tsunami in rivers in Japan and a new methodology for data processing
are used to verify that tsunami dissipation in a river at each instant and
locality depends on the tidally-modified wave-locked slope of the river
surface. As deduced from the observations, a relatively small tsunami or ocean
noise traveling at mild wave-locked slopes can propagate virtually without
losses to the upstream locations where observed tidal ranges are a fraction of
that downstream; though at the higher slopes, tidal and riverine currents
combined efficiently damp the shorter waves. The observed correlations between
the tsunami admittance upriver and the traveled wave-locked slopes are
explained analytically under the fully-nonlinear shallow-water approximation.
It is found that the wave-locked slope in a purely incident wave relates to the
bottom drag in the same manner as a steady surface slope does for a stationary
flow. For a small-amplitude tsunami in the study rivers, the wave-locked slope
in a co-propagating tidal wave defines the background current and thereby
friction experienced by the tsunami.Comment: 25 pages, 12 figure
Aerosol-radiation feedback and PM10 air concentrations over Poland

We have implemented the WRF-Chem model version 3.5 over Poland to quantify the direct and indirect feedback effects of aerosols on simulated meteorology and aerosol concentrations. Observations were compared with results from three simulations at high spatial resolutions of 5 × 5 km: (1) BASE—without any aerosol feedback effects; (2) DIR—with direct aerosol-radiative effects (3) INDIR—with direct and indirect aerosol-radiative effects. We study the overall effect during January 2011 as well as selected episodes of the highest differences in PM10 concentrations between the three simulations. For the DIR simulation, the decrease in monthly mean incoming solar radiation (SWDOWN) appears for the entire study area. It changes geographically, from about −8.0 to −2.0 W m−2, respectively for the southern and northern parts of the country. The highest changes do not correspond to the highest PM10 concentration. Due to the solar radiation changes, the surface mean monthly temperature (T2) decreases for 96 % of the area of Poland, but not more than 1.0 °C. Monthly mean PBLH changes by more than ±5 m for 53 % of the domain. Locally the differences in PBLH between the DIR and BASE are higher than ± 20 m. Due to the direct effect, for 84 % of the domain, the mean monthly PM10 concentrations increase by up to 1.9 µg m−3. For the INDIR simulation the spatial distribution of changes in incoming solar radiation as well as air temperature is similar to the DIR simulation. The decrease of SWDOWN is noticed for the entire domain and for 23 % of the domain is higher than −5.0 W m−2. The absolute differences of PBLH are slightly higher for INDIR than DIR but similarly distributed spatially. For daily episodes, the differences between the simulations are higher, both for meteorology and PM10 concentrations, and the pattern of changes is usually more complex. The results indicate the potential importance of the aerosol feedback effects on modelled meteorology and PM10 concentrations
High-resolution dynamical downscaling of ERA-Interim using the WRF regional climate model for the area of Poland. Part 1: Model configuration and statistical evaluation for the 1981–2010 period

In this work, we present the results of high-resolution dynamical downscaling of air temperature, relative humidity, wind speed and direction, for the area of Poland, with the Weather Research and Forecasting (WRF) model. The model is configured using three nested domains, with spatial resolution of 45 km × 45 km, 15 km × 15 km and 5 km × 5 km. The ERA-Interim database is used for boundary conditions. The results are evaluated by comparison with station measurements for the period 1981–2010. The model is capable of reproducing the main climatological features of the study area. The results are in very close agreement with the measurements, especially for the air temperature. For all four meteorological variables, the model performance captures seasonal and daily cycles. For the air temperature and winter season, the model underestimates the measurements. For summer, the model shows higher values, compared with the measurements. The opposite is the case for relative humidity. There is a strong diurnal pattern in mean error, which changes seasonally. The agreement with the measurements is worse for the seashore and mountain areas, which suggests that the 5 km × 5 km grid might still have an insufficient spatial resolution. There is no statistically significant temporal trend in the model performance. The larger year-to-year changes in the model performance, e.g. for the years 1982 and 2010 for the air temperature should therefore be linked with the natural variability of meteorological conditions
High-resolution dynamical downscaling of ERA-Interim using the WRF regional climate model for the area of Poland. Part 2: Model performance with respect to automatically derived circulation types

This paper presents the application of the high-resolution WRF model data for the automatic classification of the atmospheric circulation types and the evaluation of the model results for daily rainfall and air temperatures. The WRF model evaluation is performed by comparison with measurements and gridded data (E-OBS). The study is focused on the area of Poland and covers the 1981–2010 period, for which the WRF model has been run using three nested domains with spatial resolution of 45 km × 45 km, 15 km × 15 km and 5 km × 5 km. For the model evaluation, we have used the data from the innermost domain, and data from the second domain were used for circulation typology. According to the circulation type analysis, the anticyclonic types (AAD and AAW) are the most frequent. The WRF model is able to reproduce the daily air temperatures and the error statistics are better, compared with the interpolation-based gridded dataset. The high-resolution WRF model shows a higher spatial variability of both air temperature and rainfall, compared with the E-OBS dataset. For the rainfall, the WRF model, in general, overestimates the measured values. The model performance shows a seasonal pattern and is also dependent on the atmospheric circulation type, especially for daily rainfall