We describe a parallel implementation of TRIGRS, the Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability Model for the timing and distribution of rainfall-induced shallow ...landslides. We have parallelized the four time-demanding execution modes of TRIGRS, namely both the saturated and unsaturated model with finite and infinite soil depth options, within the Message Passing Interface framework. In addition to new features of the code, we outline details of the parallel implementation and show the performance gain with respect to the serial code. Results are obtained both on commercial hardware and on a high-performance multi-node machine, showing the different limits of applicability of the new code. We also discuss the implications for the application of the model on large-scale areas and as a tool for real-time landslide hazard monitoring.
•TRIGRS is a widely used model for the calculation of the timing and location of occurrence of rainfall triggered shallow landslides.•We present a fully parallel version of the code using MPI.•The software was tested both on commercial hardware and high-performance machines, showing substantial reduction of the computing time.•The new software allows simulations on very large areas and/or multiple parametric simulations in a short time.
Color fluctuations in hadron–hadron collisions are responsible for the presence of inelastic diffraction and lead to distinctive differences between the Gribov picture of high energy scattering and ...the low energy Glauber picture. We find that color fluctuations give a larger contribution to the fluctuations of the number of wounded nucleons than the fluctuations of the number of nucleons at a given impact parameter. The two contributions for the impact parameter averaged fluctuations are comparable. As a result, standard procedures for selecting peripheral (central) collisions lead to selection of configurations in the projectile which interact with smaller (larger) than average strength. We suggest that studies of pA collisions with a hard trigger may allow to observe effects of color fluctuations.
The mechanical processes involved in movements of earth or rock masses under the effect of gravity—a landslide—may include several phases where the failure of one portion of terrain can lead to the ...instability of the surrounding parts. An earlier landslide might have follow-up landslides until the landscape finds the equilibrium state. Recurring landslides are often recorded in landslide inventories but the information is seldom exploited in physical landslide modeling. Here, we study the landslide mechanism using Scoops3D—a three-dimensional, physically based landslide model. The program employs the three-dimensional column limit equilibrium and a digital elevation model to perform a slope stability analysis. Scoops3D evaluates the stability of rotational, spherical slip surfaces encompassing many grid cells, and finds the least-stable sliding surface throughout the entire digital landscape. The program generates two important outputs, namely a factor of safety map and a terrain map showing the new topographical conditions of the site with unstable areas removed. To define the final predicted landslide boundary, we have run Scoops3D repeatedly to assess the site’s stability using a newly produced terrain profile until the model predicts as stable all of the grid cells within the entire landscape. We compared the method's prediction with the actual sliding scar that took place on August 05, 2019, following a historical rainstorm in Sapa-Vietnam. Results for modified success rate, a performance metric, show that with reliable input data, the approach can predict the evolution of landslides with improved results compared to the traditional method using Scoops3D.
We perform landslide susceptibility zonation with slope units using three digital elevation models (DEMs) of varying spatial resolution of the Ubaye Valley (South French Alps). In so doing, we ...applied a recently developed algorithm automating slope unit delineation, given a number of parameters, in order to optimize simultaneously the partitioning of the terrain and the performance of a logistic regression susceptibility model. The method allowed us to obtain optimal slope units for each available DEM spatial resolution. For each resolution, we studied the susceptibility model performance by analyzing in detail the relevance of the conditioning variables. The analysis is based on landslide morphology data, considering either the whole landslide or only the source area outline as inputs. The procedure allowed us to select the most useful information, in terms of DEM spatial resolution, thematic variables and landslide inventory, in order to obtain the most reliable slope unit-based landslide susceptibility assessment.
We test the hypothesis that configurations of a proton with a large-x parton, xp ≳ 0.1, have a smaller than average transverse size. The application of the QCD Q2 evolution equations shows that these ...small configurations also have a significantly smaller interaction strength, which has observable consequences in proton-nucleus collisions. We perform a global analysis of jet production data in proton- and deuteronnucleus collisions at RHIC and the LHC. Using a model which takes a distribution of interaction strengths into account, we quantitatively extract the xp dependence of the average interaction strength, σðxpÞ, over a wide kinematic range. By comparing the RHIC and LHC results, our analysis finds that the interaction strength for small configurations, while suppressed, grows faster with collision energy than does that for average configurations. We check that this energy dependence is consistent with the results of a method which, given σðxpÞ at one energy, can be used to quantitatively predict that at another. This finding further suggests that at even lower energies, nucleons with a large-xp parton should interact much more weakly than those in an average configuration, a phenomenon in line with explanations of the EMC effect for largexp quarks in nuclei based on color screening.
We developed a Monte Carlo event generator for production of nucleon configurations in complex nuclei consistently including effects of nucleon–nucleon (NN) correlations. Our approach is based on the ...Metropolis search for configurations satisfying essential constraints imposed by short- and long-range NN correlations, guided by the findings of realistic calculations of one- and two-body densities for medium-heavy nuclei. The produced event generator can be used for Monte Carlo (MC) studies of pA and AA collisions. We perform several tests of consistency of the code and comparison with previous models, in the case of high energy proton–nucleus scattering on an event-by-event basis, using nucleus configurations produced by our code and Glauber multiple scattering theory both for the uncorrelated and the correlated configurations; fluctuations of the average number of collisions are shown to be affected considerably by the introduction of NN correlations in the target nucleus. We also use the generator to estimate maximal possible gluon nuclear shadowing in a simple geometric model.
We model effects of color fluctuations (CFs) in the light-cone photon wave function and for the first time make predictions for the distribution over the number of wounded nucleons ν in the inelastic ...photon–nucleus scattering. We show that CFs lead to a dramatic enhancement of this distribution at ν=1 and large ν>10. We also study the implications of different scales and CFs in the photon wave function on the total transverse energy ΣET and other observables in inelastic γA scattering with different triggers. Our predictions can be tested in proton–nucleus and nucleus–nucleus ultraperipheral collisions at the LHC and will help to map CFs, whose first indications have already been observed at the LHC.
GIS-based deterministic models may be used for landslide susceptibility mapping over large areas. However, such efforts require specific strategies to (i) keep computing time at an acceptable level, ...and (ii) parameterize the geotechnical data. We test and optimize the performance of the GIS-based, 3-D slope stability model r.slope.stability in terms of computing time and model results. The model was developed as a C- and Python-based raster module of the open source software GRASS GIS and considers the 3-D geometry of the sliding surface. It calculates the factor of safety (FoS) and the probability of slope failure (Pf) for a number of randomly selected potential slip surfaces, ellipsoidal or truncated in shape. Model input consists of a digital elevation model (DEM), ranges of geotechnical parameter values derived from laboratory tests, and a range of possible soil depths estimated in the field. Probability density functions are exploited to assign Pf to each ellipsoid. The model calculates for each pixel multiple values of FoS and Pf corresponding to different sliding surfaces. The minimum value of FoS and the maximum value of Pf for each pixel give an estimate of the landslide susceptibility in the study area. Optionally, r.slope.stability is able to split the study area into a defined number of tiles, allowing parallel processing of the model on the given area. Focusing on shallow landslides, we show how multi-core processing makes it possible to reduce computing times by a factor larger than 20 in the study area. We further demonstrate how the number of random slip surfaces and the sampling of parameters influence the average value of Pf and the capacity of r.slope.stability to predict the observed patterns of shallow landslides in the 89.5 km2 Collazzone area in Umbria, central Italy.
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