Soil liquefaction potential induced by the andalusian earthquake of 25 December 1884

On 25 December 1884, an earthquake of epicentral intensityI ₀ = IX in the MSK scale caused great damage in a large area in the provinces of Granada and Málaga, in the south of Spain. The reports of the Spanish, Italian and French Commissions that studied the earthquake described ground phenomena in seven different sites which can be identified as soil liquefaction.By means of dynamic penetration tests carried out in the above sites, the corresponding soil profiles (based on SPT data and water table depth) were established, and the occurrence of liquefaction was proved in five out of seven of these sites. Also, the intensities at such locations and the magnitude of the earthquake were estimated.From the geotechnical data and the cyclic stress ratio induced by the earthquake, liquefaction conditions were confirmed in all the five sites which presumably liquefied. Then, possible values of the minimum ground surface accelerations necessary for the onset of liquefaction at each location were calculated. The results obtained were completed with data reported in six liquefaction case studies from Japan and the United States, from which design charts relating soil acceleration with normalized SPT values for different intensity levels were drawn.Finally, by using standard attenuation curves, the above data were translated into epicentral distances, and good agreement with the known epicentral area was found. As a result, a consistent approach for liquefaction hazard and source location problems has been developed. The proposed method combines in its formulation historical evidence and earthquake engineering techniques.     

Synchrotron-based X-ray study of iron oxide transformations in terraces from the Tinto-Odiel river system: Influence on arsenic mobility

Simultaneous analysis of micro-X-ray diffraction (μ-XRD) and micro-X-ray fluorescence (μ-XRF) based on synchrotron light sources, and electron microprobe (EMP) analyses, were performed on iron terrace samples taken from Tinto-Odiel river system from the Iberian Pyrite Belt (IBP, SW Iberian Peninsula). Iron terraces are formed during the oxidation and precipitation of dissolved iron along the riverbeds impacted by acid mine drainage (AMD). This paper includes the study of actively-forming current terraces and fossil terraces isolated from the stream courses due to the river migration over time. The results of the study of current terrace samples from AMD-affected streams of two IPB abandoned mines (Tinto Santa Rosa and Cueva de la Mora) showed that fresh precipitates at the surface are composed primarily of metastable schwertmannite, which is gradually transformed at depth over short-time scales into goethite. Sediments of ancient terraces are composed mainly of goethite, which most likely originated from the re-crystallization of a precursor schwertmannite. However, at century-time scale, goethite partially re-crystallizes to hematite due to diagenetic processes. The transformation rate of goethite into hematite is negatively correlated with grain size and the crystallinity of goethite. Moreover, this transformation is accompanied by an increase in grain size and a decrease in surface area of hematite, and a concomitant decrease in arsenic trapped in the solid. This increase in the arsenic mobility during the diagenetic maturation should be considered in the development of conceptual and analytical models describing long-term fate, transport and bioavailability of arsenic in environmental systems.     

Siltstone from Southern Patagonia: Its Source and Archaeological Artifact Distribution in Santa Cruz Province,Argentina

Hunter‐gatherer mobility and spheres of interaction are important characteristics worthy of investigation in Patagonian archaeology. One way to approach these is by studying the distribution of lithic archaeological materials. Siltstone (limolite) artifacts are found along the western strip of southwestern Patagonia, Argentina. Based on geomorphological studies and the high density of archaeological material, a source was located along the western margin of Cardiel Lake. Neutron activation analysis of samples from the source and archaeological sites in several neighboring basins allowed us to model its circulation. Siltstone's archaeological distribution indicates that its regional circulation had a southerly direction dating from the early Holocene. This southern vector shows an important difference when compared to the distribution of obsidian from Pampa del Asador, which has a broader circulation pattern. This could be related to a greater availability of high‐quality lithic materials north of the siltstone source. This work also contributes to the construction of a lithic source database for southern Patagonia.     

Performance evaluation of implicit stochastic reservoir operation optimization supported by long-term mean inflow forecast

This study applies implicit stochastic optimization (ISO) to develop monthly operating rules for a reservoir located in Northeast Brazil. The proposed model differs from typical ISO applications as it uses the forecast of the mean inflow for a future horizon instead of the current-month inflow. Initially, a hundred different 100-year monthly inflow scenarios are synthetically generated and employed as input to a deterministic operation optimization model in order to build a database of optimal operating data. Later, such database is used to fit monthly reservoir rule curves by means of nonlinear regression analysis. Finally, the established rule curves are validated by operating the system under 100 new inflow ensembles. The performance of the proposed technique is compared with those provided by the standard reservoir operating policy (SOP), stochastic dynamic programming (SDP) and perfect-forecast deterministic optimization (PFDO). Different forecasting horizons are tested. For all of them, the results indicate the feasibility of using ISO in view of its lower vulnerability in contrast to the SOP as well as the proximity of its operations with those by PFDO. The results also reveal that there is an optimal choice for the forecasting horizon. The comparison between ISO and SDP shows small differences between both, justifying the adoption of ISO for its simplified mathematics as opposed to SDP.     

Disjunctive kriging, universal kriging, or no kriging: Small sample results with simulated fields

This paper provides a comparison between linear (universal) and nonlinear (disjunctive) kriging estimators when they are computed from small samples chosen randomly on simulated stationary and nonstationary fields. Point estimation results are reported. In all cases considered, kriging estimators were found better than a local mean estimator, with universal kriging either better than or as good as disjunctive kriging. The latter, which is suited to handle stationary fields, did not provide more accurate estimates because the use of small samples led to inconsistencies in the assumed bivariate model. Universal kriging was particularly better with nonstationary fields.     

Hypothesis of the multiple subsidence trough related to very steep and vertical coal seams and its prediction through profile functions

Coalfields in the north of Spain (Asturias) are mainly steeply dipping and at considerable depth. There is widespread use of caving mining methods at the present time. This paper describes a theory developed to predict the subsidence related to very steep and nearly vertical coal seams (70°–90°). This theory of the multiple subsidence trough is applied through a new profile function. Three real cases are analysed and the profile function is adjusted. An empirical relationship between the parameters of the new profile function and geological and mining factors has been developed.     

A Comparative Study of the Use of Organoclay‐Based Formulations and Organic Amendment to Reduce the Leaching of the Herbicide MCPA in Soil

MCPA (4‐chloro‐2‐methylphenoxyacetic acid) is an acidic herbicide widely used on olive crops in Spain. Due to its anionic form at natural soil pH, there is high risk of leaching and groundwater contamination by the use of this herbicide. The aim of this work was to study the effects of organoclay‐based formulations of MCPA and olive oil waste amendment on MCPA leaching in a sandy loam soil. For this purpose, batch adsorption and column leaching studies were performed. The organoclays used to prepare the clay‐based formulations of MCPA were obtained by treating Wyoming montmorillonite (SWy‐2) and Arizona montmorillonite (SAz‐1) with an amount of hexadecyltrimethylammonium (HDTMA) cation equal to 100% of the CEC of the montmorillonites. The organic residue used in this study was a solid waste from olive oil production (olive oil waste, OOW). The soil was amended with the organic residue at the rate of 10% (w/w). Batch release and column leaching studies indicated that organoclay‐based formulations of MCPA reduced the release rate and the leaching of the herbicide as compared to the use of a conventional formulation containing the herbicide in an immediately available form. The increase in soil organic matter of the soil upon amendment with the organic residue also resulted in greater adsorption and reduced leaching of MCPA in the soil. Accordingly, both the use of organoclay‐based formulations and the amendment of soil with OOW are proposed as efficient strategies to reduce extensive leaching losses associated with the application of MCPA in high‐risk scenarios, such as Mediterranean olive groves.     

Review of the El Soplao Amber Outcrop,Early Cretaceous of Cantabria,Spain

<正>El Soplao outcrop,an Early Cretaceous amber deposit recently discovered in northern Spain (Cantabria),has been shown to be the largest site of amber with arthropod inclusions that has been found in Spain so far.Relevant data provided herein for biogeochemistry of the amber,palynology,taphonomy and arthropod bioinclusions complement those previously published.This set of data suggests at least two botanical sources for the amber of El Soplao deposit.The first(type A amber)strongly supports a source related to Cheirolepidiaceae,and the second(type B amber)shows non-specific conifer biomarkers.Comparison of molecular composition of type A amber with Frenelopsis leaves(Cheirolepidiaceae)strongly suggests a biochemical affinity and a common botanical origin.A preliminary palynological study indicates a regional high taxonomical diversity,mainly of pteridophyte spores and gymnosperm pollen grains.According to the preliminary palynological data,the region was inhabited by conifer forests adapted to a dry season under a subtropical climate.The abundant charcoalified wood associated with the amber in the same beds is evidence of paleofires that most likely promoted both the resin production and an intensive erosion of the litter,and subsequent great accumulation of amber plus plant cuticles.In addition,for the first time in the fossil record, charcoalified plant fibers as bioinclusions in amber are reported.Other relevant taphonomic data are the exceptional presence of serpulids and bryozoans on the surfaces of some amber pieces indicating both a long exposure on marine or brackish-water and a mixed assemblage of amber.Lastly,new findings of insect bioinclusions,some of them uncommon in the fossil record or showing remarkable adaptations,are reported.In conclusion,a documented scenario for the origin of the El Soplao amber outcrop is provided.