ALBERT

Description: Forests, Vol. 9, Pages 480: Modelling the Effect of Weed Competition on Long-Term Volume Yield of Eucalyptus globulus Labill. Plantations across an Environmental Gradient Forests doi: 10.3390/f9080480 Authors: Felipe Vargas Carlos A. Gonzalez-Benecke Rafael Rubilar Manuel Sanchez-Olate Several studies have quantified the responses of Eucalyptus globulus Labill. plantations to weed control on its early development (2–3 years after establishment). However, long-term results of competing vegetation effects have not been included into growth and yield models that incorporate treatments of competing vegetation control, and its interaction with site resource availability. In this article, we compared several models predicting stand volume yield of E. globulus plantations established across an environmental gradient, growing under different intensity levels of competing vegetation control. Four sites were selected encompassing a gradient in rainfall and amount of competing vegetation. Treatments were applied at stand establishment and were monitored periodically until age 9 years. Competing vegetation control intensity levels considered 0, 5, 20, 44, and 100% weed-free cover around individual E. globulus cuttings. Maximum competing vegetation biomass production during the first growing season were 2.9, 6.5, 2.2, and 12.9 Mg ha−1, for sites ranging from low to high annual rainfall. As expected, reductions in volume yield at age 9 years were observed as competing vegetation control intensity decreased during the first growing season. A strong relationship was established between stem volume yield loss and the intensity of competing vegetation control, the amount of competing vegetation biomass produced during the first growing season and mean annual rainfall. The slope of the relationship was different among sites and was related mainly to water and light limitations. Our results suggest that the biomass of competing vegetation (intensity of competition), affecting site resource availability, contribute to observed long-term effects on E. globulus plantations productivity. The site with the lowest mean annual rainfall showed the highest volume yield loss at age 9 years. Sites with highest rainfall showed contrasting results related to the amount of competing vegetation biomass.

Description: The Colombian volcano Galeras is one of the most active volcanoes in the world, and it has an andesitic composition and high explosive potential. We consider the period of 1989–2015, in which the volcano manifested frequent eruptions and high seismic activity. To study the temporal variations in the seismic structure beneath Galeras, we implemented an algorithm of repeated tomography using selected data sets with similar geometries. We obtained the variations in the seismic velocity structures beneath Galeras during the three time episodes of 1989–2000, 2001–2007, and 2008–2015. In the second episode, we observe a columnar anomaly with a high V p/V s ratio that possibly represents a conduit transporting a new portion of magma material from below. This result may indicate that in this period, which culminated with dome emplacement and collapse, the volcano was directly fed from deeper magma sources. In other episodes, the conduit is less visible in the tomography models, and we propose that the volcanic activity was merely controlled by shallow magma reservoirs at 2–4 km below the surface. ©2018. American Geophysical Union. All Rights Reserved.

Description: During the outgoing year, successful events took place, as Latin American and Caribbean Seismological Commission Assembly, on July 23, 24, 25, in Bogotá, Colombia. In that academic event, the relevant results associated with the seismotectonic behavior of the Latin America and Caribbean region were addressed, as well as the implications of active exploration of the tectonic conditions, the socio-economic impacts of exploration and extraction of economic resources, and the implementation of non-conventional techniques for exploring and mining that can contribute to sustainable development. Another event was the Shale Colombia 2014, unconventional oil and gas development congress, aimed to determine the next steps towards the commercialization of unconventional oil and gas development for the country. The event hosted case studies from some of the pioneers in Colombian development, using the latest reservoir data fiscal updates and global scale technology case studies, to evaluate real potential Colombia holds for unconventional development. In the outlook of 2015, one of the main events is the 26th International Union of Geodesy and Geophysics General Assembly, to be realized between June 22 and July 2, in Prague, Czech Republic. You are on time to participate in this event yet. In Colombia will take place the XV Colombian Congress of Geology on 31 August to 5 September. This event is a bi-annual meeting gathering scientists, academicians, and researchers from the region, with an extensive participation of international guests. The Congress wants to provide a scenery to discuss the perspectives of mineral resources, new exploration techniques related to energy supply, proposals for optimized management of mining and mineral resources, between other topics. Finally, we want to introduce you the manuscripts selected for this edition. There is a broad range of information about seismology with four papers coming from different countries. The first one is an analysis of the elastic structure beneath Australia shown by means of S-velocity maps and determined by the regionalization and inversion of Rayleigh wave dispersion. The obtained S-velocity models suggest the existence of lateral and vertical heterogeneity in the structure. From Turkey, the second manuscript presents a site response analysis and estimation of S-wave velocity depending on acceleration data. The other two articles in seismology for this edition are based on improving accuracy and reliability of the first arrival times through Cross Correlation Technique, and in the characterization of seismic events using only one seismological station. In other knowledge field, it is presented a mineralization potential study of the intrusive bodies in Valis, northwest of Iran. A very graphical manuscript coming from the Gaza strip shows a study in sand dunes, from morphology, textural characteristics, and associated environmental impacts. From Morocco, a study aimed to evaluate geostatistical methods for delimitation of anomalies detected in the phosphatic series of Sidi Chenane found that the exponential model is the best one to represent the spatial variability of their geoelectric data; models of the geology were successfully obtained from geostatistical method, which help mapping the phosphate deposit inclusions and the estimations of phosphate reserves were improved and better constrained. In geotechnics, three important works are displayed. One is about the experimental triaxial tests developed to estimate undrained critical shear strength under monolithic loadings; the second one reads about classification of caving depth by feature extraction in cutting images, and the other is a simulation using artificial neural network and adaptative neuro-fuzzy system of compression ratio in a municipal solid waste. Last two works talk about GIS and Kriging techniques applied to map a spatial distribution of sediments pollution in the Khajeh Kory river and an assessment of the land ecological security for Yancheng city, in China. We hope you may find interesting information in our ESRJ.   Carlos Alberto Vargas Earth Sciences Research Journal Editor in Chief 

Description: Seismic event characterization is often accomplished using algorithms based only on information received at seismological stations located closest to the particular event, while ignoring historical data received at those stations. These historical data are stored and unseen at this stage. This characterization process can delay the emergency response, costing valuable time in the mitigation of the adverse effects on the affected population. Seismological stations have recorded data during many events that have been characterized by classical methods, and these data can be used as previous “knowledge” to train such stations to recognize patterns. This knowledge can be used to make faster characterizations using only one three-component broadband station by applying bio-inspired algorithms or recently developed stochastic methods, such as kernel methods. We trained a Support Vector Machine (SVM) algorithm with seismograph data recorded by INGEOMINAS’s National Seismological Network at a three-component station located near Bogota, Colombia. As input model descriptors, we used the following: (1) the integral of the Fourier transform/power spectrum for each component, divided into 7 windows of 2 seconds and beginning at the P onset time, and (2) the ratio between the calculated logarithm of magnitude (Mb) and epicentral distance. We used 986 events with magnitudes greater than 3 recorded from late 2003 to 2008.The algorithm classifies events with magnitude-distance ratios (a measure of the severity of possible damage caused by an earthquake) greater than a background value. This value can be used to estimate the magnitude based on a known epicentral distance, which is calculated from the difference between P and S onset times. This rapid (〈 20 seconds) magnitude estimate can be used for rapid response strategies.The results obtained in this work confirm that many hypocentral parameters and a rapid location of a seismic event can be obtained using a few seconds of signal registered at a single station. A cascade scheme of SVMs or other appropriate algorithms can be used to completely classify an event in a very short time with acceptable accuracy using data from only one station.   Resumen Los algoritmos de determinación de parámetros hipocentrales empleados en la actualidad, se basan específicamente en la información recibida en las estaciones de monitoreo mas cercanas al epicentro y no tienen en cuenta la valiosa información histórica registrada a lo largo del tiempo en dichas estaciones. Es por esto que los procesos de caracterización toman varios minutos, tiempo precioso que podría ser de gran utilidad en la generación de alertas tempranas que permitan una oportuna reacción ante el evento. El registro de información, a lo largo el tiempo, de sismos ocurridos en los alrededores de la estación, puede ser empleada para dotarla de algún grado de experiencia que le permita, mediante detección y clasificación de patrones, realizar una caracterización previa mucho mas rápida, mediante el empleo de técnicas modernas las cuales pueden ser algoritmos bio-inspirados o métodos estocásticos mas recientes conocidos como métodos Kernel. En el presente trabajo se emplea un método conocido como Maquinas de Soporte Vectorial (MSV), entrenando dicho algoritmo con información de la relación del área bajo la curva de la potencia de la transformada de Fourier de las componentes N-S, E-W y Vertical, calculada para 5 ventanas de 2 segundos, desde la onda p, de 123 sismos de magnitud superior a 3, desde 2004 hasta 2008, alrededor de la estación El Rosal, de la Red Sismológica Nacional de Ingeominas. El Algoritmo clasifica sismos que superen un umbral predeterminado de la relación entre el Logaritmo de la magnitud y la distancia, que refleja, de alguna manera, la intensidad del sismo. Con la obtención de este parámetro será posible conocer la magnitud del evento, debido a que la distancia puede ser calculada, con base en picado de la onda S, y de esta manera establecer una aproximación rápida de la magnitud en un tiempo aproximado de 20 segundos después del evento. Los resultados obtenidos permiten confirmar que con poco tiempo se señal en una sola estación sismológica es posible obtener información confiable para ser empleada en alertas tempranas.

Description: We have conducted experiments of the Faraday instability in a network of square cells filled with water for driving frequencies and amplitudes in the intervals 10≤F≤22 Hz and 0.1≤A≤3 mm, respectively. The experiments were aimed at studying the effects of varying the size of the cells on the surface wave patterns. Images of the surface wave patterns were recorded with a high-speed camera. The time series of photographs composing each video was Fourier analyzed, and information about the waveforms was obtained by using a Pearson correlation analysis. For small square cells of side length l=2.5 cm, adjacent cells collaborate synchronously to form regular patterns of liquid bumps over the entire grid, while ordered matrices of oscillons are formed at higher frequencies. As the size of the cells is increased to l=5 cm, collective cell behaviour at lower frequencies is no longer observed. As the frequency is increased, a transition from three triangularly arranged oscillons within each cell to three, or even four, irregularly arranged oscillons is observed. The wave patterns, the waveforms and the energy content necessary to excite Faraday waves are seen to depend on the cell size.