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Porcu E.,Federico Santa María Technical University | Fasso A.,University of Bergamo | Barrientos S.,University of Chile | Catalan P.A.,Federico Santa María Technical University | Catalan P.A.,National Research Center Para La Gestion Integrada Of Desastres Naturales
Stochastic Environmental Research and Risk Assessment | Year: 2017

We review the origin and the meaning of the term seismomatics. In doing, this historical and recent seismicity of Chile is discussed. Moreover, the papers appearing in the special issue on seismomatics are briefly reviewed. © 2017 Springer-Verlag Berlin Heidelberg


Loveless J.P.,Smith College | Scott C.P.,Cornell University | Allmendinger R.W.,Cornell University | Gonzalez G.,Católica del Norte University | Gonzalez G.,National Research Center Para La Gestion Integrada Of Desastres Naturales
Geophysical Research Letters | Year: 2016

The 2014 Mw = 8.1 Iquique (Pisagua), Chile, earthquake sequence ruptured a segment of the Nazca-South America subduction zone that last hosted a great earthquake in 1877. The sequence opened >3700 surface cracks in the fore arc of decameter-scale length and millimeter-to centimeter-scale aperture. We use the strikes of measured cracks, inferred to be perpendicular to coseismically applied tension, to estimate the slip distribution of the main shock and largest aftershock. The slip estimates are compatible with those based on seismic, geodetic, and tsunami data, indicating that geologic observations can also place quantitative constraints on rupture properties. The earthquake sequence ruptured between two asperities inferred from a regional-scale distribution of surface cracks, interpreted to represent a modal or most common rupture scenario for the northern Chile subduction zone. We suggest that past events, including the 1877 earthquake, broke the 2014 Pisagua source area together with adjacent sections in a throughgoing rupture. ©2016. American Geophysical Union. All Rights Reserved.


Foy C.,313 Sherman St. | Arabi M.,Colorado State University | Yen H.,Texas AgriLife Research Center | Yen H.,U.S. Department of Agriculture | And 3 more authors.
Journal of Hydrologic Engineering | Year: 2015

Hydrologic fluxes in mountainous watersheds are particularly important as these areas often provide a significant source of freshwater for more arid surrounding lowlands. The state of Colorado in the United States comprises a principal snow catchment area, with all major headwater river basins in Colorado providing substantial water flows to surrounding western and midwestern states. The ability to represent and quantify hydrologic processes controlling the generation and movement of water in headwater basins of Colorado therefore has significant implications for effective management of water resources in the western United States under varying climatic and land-use conditions. In the research reported in this paper, hydrologic modeling was applied to four snow-dominated, mountainous basins of Colorado [i.e., the river basins of (1) Cache la Poudre, (2) Gunnison, (3) San Juan, and (4) Yampa] to evaluate the relevance of specific hydrologic components (i.e., evapotranspiration, snow processes, groundwater processes, surface runoff, and so on) in the complex, high-elevation watersheds. The soil and water assessment tool (SWAT) model was calibrated and tested for multiple river locations within each basin using monthly naturalized flows over the 1990-2005 period. The model was able to adequately simulate streamflows at all locations within the four basins. Monthly patterns of precipitation, snowfall, evapotranspiration (ET), and total water yield were similar for all the basins, while subsurface lateral flow was the dominant hydrologic pathway, contributing between 64 and 82% to gross basin water yields on an average annual basis. Overall, results indicated the strong influence of snowmelt and groundwater processes on amounts and timing of streamflows in the study basins. Hence, enhanced representation of these processes may be essential to improve hydrological estimation using computer software in snowmelt-driven mountainous basins. In particular, examination of monthly streamflow residuals indicated that the normality and independence of model residuals, which are often assumed in parameter estimation and uncertainty analysis, were not always satisfied. © 2015 American Society of Civil Engineers.


Almar R.,French National Center for Space Studies | Michallet H.,CNRS Laboratory of Geophysical and Industrial Flows | Cienfuegos R.,University of Santiago de Chile | Cienfuegos R.,National Research Center Para La Gestion Integrada Of Desastres Naturales | And 3 more authors.
Coastal Engineering | Year: 2014

In the nearshore, describing the complex individual wave dynamics remains a key challenge. In this paper we test the ability of the Radon Transform to produce estimates of individual wave celerities and to separate incoming and outgoing waves conserving the temporal characteristics. The Radon Transform is a projection of a two-dimensional field into polar space. Oblique features such as propagating crests in a spatio-temporal space are identified with density peaks in the polar space. In this paper, the Radon Transform is applied to synthetic test cases including a wide range of beach slopes and wave conditions. The Radon Transform shows good skills at estimating individual celerity and separating incoming and outgoing components with a relative RMS error lower than 10%, even a standing wave node. The accuracy is fairly insensitive to wave characteristics whereas the main limitations rise from the sampling scheme and are the number and density of wave gauges. The distance between gauges should be less than one third of the shortest wavelength, while the set of gauges should cover more than one third of the longest wavelength. © 2014 Elsevier B.V.


Okuwaki R.,University of Tsukuba | Yagi Y.,University of Tsukuba | Aranguiz R.,University of Concepción | Aranguiz R.,National Research Center Para La Gestion Integrada Of Desastres Naturales | And 4 more authors.
Pure and Applied Geophysics | Year: 2016

We constructed a seismic source model for the 2015 MW 8.3 Illapel, Chile earthquake, which was carried out with the kinematic waveform inversion method adopting a novel inversion formulation that takes into account the uncertainty in the Green’s function, together with the hybrid backprojection method enabling us to track the spatiotemporal distribution of high-frequency (0.3–2.0 Hz) sources at high resolution by using globally observed teleseismic P-waveforms. A maximum slip amounted to 10.4 m in the shallow part of the seismic source region centered 72 km northwest of the epicenter and generated a following tsunami inundated along the coast. In a gross sense, the rupture front propagated almost unilaterally to northward from the hypocenter at <2 km/s, however, in detail the spatiotemporal slip distribution also showed a complex rupture propagation pattern: two up-dip rupture propagation episodes, and a secondary rupture episode may have been triggered by the strong high-frequency radiation event at the down-dip edge of the seismic source region. High-frequency sources tends to be distributed at deeper parts of the slip area, a pattern also documented in other subduction zone megathrust earthquakes that may reflect the heterogeneous distribution of fracture energy or stress drop along the fault. The weak excitation of high-frequency radiation at the termination of rupture may represent the gradual deceleration of rupture velocity at the transition zone of frictional property or stress state between the megathrust rupture zone and the swarm area. © 2016, Springer International Publishing.


Dorsaz J.-M.,University of Santiago de Chile | Dorsaz J.-M.,Ecole Polytechnique Federale de Lausanne | Gironas J.,University of Santiago de Chile | Gironas J.,National Research Center Para La Gestion Integrada Of Desastres Naturales | And 4 more authors.
Earth Surface Processes and Landforms | Year: 2013

Endorheic basins are catchments with no hydrological connection with marine environments. They cover 20% of the Earth's surface, and are mostly located in arid regions. Their drainage networks converge to lakes, salt flats or alluvial plains, whose dynamics are strongly driven by precipitation, evapotranspiration and groundwater discharge, among other factors. Integrated surface drainage and the creation of whole drainage systems typical of open basins are commonly restricted in these regions. Interestingly, the fluvial basin morphology of endorheic basins has not been extensively studied, and a variety of quantitative morphological descriptors used in open basins have not been utilized in the geomorphic analysis of endorheic basins. The objective of this study is to better understand the basin morphology of endorheic river basins by using well-known geomorphological properties and their variations across scales. For three basins in northern Chile we computed the following descriptors and the corresponding relevant scales: the cumulative distribution of contributing area, the horizontal shape of the basins (i.e. Hack's law, normalized Euclidean length, and sinuosity of the streams), slope-area relationship, Horton's ratios and drainage density. We detected several properties typically found in open basins, but certain features which seem to be unique to closed basins were also identified. In particular, we found that horizontal and vertical geomorphic features seem to be linked, which suggests that an independent treatment of these features may not be appropriate for closed basins. Similar results were found regardless of the basin area, which illustrates the relevant effects of features that are specific to these particular regions. It is expected that our findings will improve both the geomorphic assessment of these basins and hydrological modelling of surface water and groundwater. © 2013 John Wiley & Sons, Ltd.


Catalan P.A.,Federico Santa María Technical University | Catalan P.A.,National Research Center Para La Gestion Integrada Of Desastres Naturales | Catalan P.A.,Cctval Centro Cientifico Tecnologico Of Valparaiso | Haller M.C.,Oregon State University | Plant W.J.,University of Washington
Journal of Geophysical Research: Oceans | Year: 2014

The microwave backscatter properties of surf zone waves are analyzed using field observations. By utilizing a preexisting, independent, water surface discrimination technique, the microwave returns were extracted along individual waveforms and the data from shoaling (steepening) waves, surf zone breaking waves, and remnant foam were separated and quantified. In addition, a wave tracking analysis technique allows the returns to be examined on a wave-by-wave basis as individual waves progress through the shoaling zone and break on a nearshore sand bar. Normalized radar cross sections (NRCS), polarization ratios, Doppler spectra, and scatterer velocities were collected using a dual-polarized, X-band radar operating at lower grazing angles than previously reported (1-3.5). The results indicate that the maximum NRCS levels are from the active breaking portions of the wave and were consistently about -20 dB, regardless of radar polarization, azimuth angle, wave height, or wind speed. In addition, breaking waves induce broadening of the Doppler spectra and mean scatterer velocities that correlate well with the carrier wave celerity. Analysis of the polarization ratios suggest that the active breaking portions of the wave are depolarized but that higher polarization ratios (>0 dB) are found on the leading edges shoreward of the active breaking portions of the waves, which indicates a clear distinction between two scattering regimes. These results are consistent with scattering from a very rough surface that is being mechanically generated by the breaking process, showing a good agreement with the expected grazing angle dependency of a Lambertian scatterer. Key Points Breaking waves scatter energetically, regardless of polarization, wave, or wind NRCS of active breaking correlates well with Lambertian scattering Only one breaking event suffices to broaden Doppler spectra © 2014. American Geophysical Union. All Rights Reserved.


Flores R.P.,Federico Santa María Technical University | Flores R.P.,University of Washington | Catalan P.A.,Federico Santa María Technical University | Catalan P.A.,National Research Center Para La Gestion Integrada Of Desastres Naturales | And 2 more authors.
Coastal Engineering | Year: 2016

The spatial distribution of wave roller dissipation is derived from optical remote sensing observations in a laboratory setting and is used to estimate wave transformation and radiation stress forcing through the surfzone. The methodology relies on direct measurements of the size of individual wave breaking rollers in an irregular wave field via remote sensing. The wave roller measurements are used to calculate the roller energy, roller dissipation, and the roller component of the radiation stress. These hydrodynamic quantities then serve as input into the wave energy flux and cross-shore momentum balances in order to derive the wave height transformation and mean water level profiles. The accuracy of the methodology is shown to be very good through comparison with in situ data. In addition, the mean water level profile reproduces the transition zone lag and maximum water level at the most shoreward measuring point. Overall, it is demonstrated that the methodology can be successfully applied to irregular waves and can be used to estimate both wave transformation and radiation stress forcing through the surf zone. © 2016 Elsevier B.V.


Fernandez B.,Pontifical Catholic University of Chile | Gironas J.,Pontifical Catholic University of Chile | Gironas J.,National Research Center Para La Gestion Integrada Of Desastres Naturales
Drought: Research and Science-Policy Interfacing - Proceedings of the International Conference on Drought: Research and Science-Policy Interfacing | Year: 2015

Chile has a wide variety of climates due to its geographical location, which covers over 4000 km from tropical regions in the north to the south Polar Regions. Drought of varying size and durations affecting different parts of the territory are commonly observed, including areas such as the arid Atacama Desert, the semi-arid central region, and the humid and very humid areas in the south. Despite the diversity of climates and weather conditions, the management of water resources in Chile is centralized. Thus, prior to making management decisions to cope with drought, the central water authority, must declare a drought as extraordinary. It is only after this declaration that the state can use public money to deliver aids, provide subsidies, allocate resources and implement other management tools. Recently the Standardized Precipitation Index (SPI) and the Standardized Runoff Index (SRI) were proposed as common indices to declare drought in the entire country. We studied the behavior of these indices throughout the territory for different durations (i.e., from 1 to 12 months), in order to identify the values that can be used to effectively declare extraordinary drought conditions in each region of the country. These indices were incorporated to the DGA's regulation for declaring drought in 2012, and have become common and objective tools to deal with drought in Chile. © 2015 Taylor & Francis Group, London.


Guerra M.,University of Santiago de Chile | Cienfuegos R.,University of Santiago de Chile | Cienfuegos R.,National Research Center Para La Gestion Integrada Of Desastres Naturales | Escauriaza C.,University of Santiago de Chile | And 4 more authors.
Journal of Hydraulic Engineering | Year: 2014

The consequences of rapid and extreme flooding events, such as tsunamis, riverine flooding, and dam breaks show the necessity of developing efficient and accurate tools for studying these flow fields and devising appropriate mitigation plans for threatened sites. Twodimensional simulations of these flows can provide information about the temporal evolution of water depth and velocities, but the accurate prediction of the arrival time of floods and the extent of inundated areas still poses a significant challenge for numerical models of rapid flows over rough and variable topographies. Careful numerical treatments are required to reproduce the sudden changes in velocities and water depths, evolving under strong nonlinear conditions that often lead to breaking waves or bores. In addition, new controlled experiments of flood propagation in complex geometries are also needed to provide data for testing the models and evaluating their performance in more realistic conditions. This work implements a robust, well-balanced numerical model to solve the nonlinear shallow water equations (NSWEs) in a nonorthogonal boundary fitted curvilinear coordinate system. It is shown that the model is capable of computing flows over highly variable topographies, preserving the positivity of the water depth, and providing accurate predictions for the wetting and drying processes. The model is validated against benchmark cases that consider the use of boundary fitted discretizations of the computational domain. In addition, a laboratory experiment is performed of a rapid flood over a complex topography, measuring the propagation of a dam break wave on a scaled physical model, registering time series of water depth in 19 cross sections along the flow direction. The data from this experiment are used to test the numerical model, and compare the performance of the current model with the numerical results of two other recognized NSWE models, showing that the current model is a reliable tool for efficiently and accurately predicting extreme inundation events and longwave propagation over complex topographies. © 2014 American Society of Civil Engineers.

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