Combining filter based feature selection methods and gaussian mixture model for real-time seismic event classification at Cotopaxi volcan

This paper proposes an exhaustive evaluation of five different filter-based feature selection methods in combination with a Gaussian Mixture Model classifier for almost real time classification of Long-Period and Volcano-Tectonic seismic events recorded at Cotopaxi volcano in Ecuador between 2009 and 2010...Este artículo propone una evaluación exhaustiva de cinco diferentes métodos de selección de características basados en filtrado, en combinación con el Modelo Mixto Gaussiano como clasificador para la categorización prácticamente en tiempo real de eventos sísmicos Largo-Período y Vulcano-Tectónico grabados en el volcán Cotopaxi en Ecuador entre 2009 y 2010..

A New Classification Method of Infrasound Events Using Hilbert-Huang Transform and Support Vector Machine

Infrasound is a type of low frequency signal that occurs in nature and results from man-made events, typically ranging in frequency from 0.01 Hz to 20 Hz. In this paper, a classification method based on Hilbert-Huang transform (HHT) and support vector machine (SVM) is proposed to discriminate between three different natural events. The frequency spectrum characteristics of infrasound signals produced by different events, such as volcanoes, are unique, which lays the foundation for infrasound signal classification. First, the HHT method was used to extract the feature vectors of several kinds of infrasound events from the Hilbert marginal spectrum. Then, the feature vectors were classified by the SVM method. Finally, the present of classification and identification accuracy are given. The simulation results show that the recognition rate is above 97.7%, and that approach is effective for classifying event types for small samples

Application of Geographical Information Systems to Lahar Hazard Assessment on an Active Volcanic System

Lahars (highly dynamic mixtures of volcanic debris and water) have been responsible for some of the most serious volcanic disasters and have killed tens of thousands of people in recent decades. Despite considerable lahar model development in the sciences, many research tools have proved wholly unsuitable for practical application on an active volcanic system where it is difficult to obtain field measurements. In addition, geographic information systems are tools that offer a great potential to explore, model and map hazards, but are currently under-utilised for lahar hazard assessment. This research pioneered a three-tiered approach to lahar hazard assessment on Montserrat, West Indies. Initially, requirements of potential users of lahar information (scientists and decision-makers) were established through interview and evaluated against attainable modelling outputs (given flow type and data availability). Subsequently, a digital elevation model, fit for modelling lahars, was used by a path of steepest descent algorithm and a semi-empirical debris-flow model in the prediction of lahar routes and inundation areas. Limitations of these established geographical information system (GIS) based models, for predicting the behaviour of (relatively under-studied) dilute lahars, were used to inform key parameters for a novel model, also tightly coupled to a GIS, that simulated flow routes based on change in velocity. Importantly, uncertainty in model predictions was assessed through a stochastic simulation of elevation error. Finally, the practical utility of modelling outputs (visualisations) was assessed through mutual feedback with local scientists. The new model adequately replicated past flow routes and gave preliminary predictions for velocities and travel times, thus providing a short-term lahar hazard assessment. Inundation areas were also mapped using the debris-flow model to assist long-term planning. Ultimately, a GIS can support ‘on the ground’ planning decisions, but efficacy is limited by an active volcanic system which can restrict feedback to and from end-users. *[The appendices for this thesis were submitted as separate files which could not be uploaded to the repository. Please contact the author for more information.]

El Hierro Island Global Geopark

This open access book explores El Hierro Island, which is geologically the youngest of the Canary Islands (Spain). Having registered its latest volcanic eruption in 2011-2012, it is an oceanic subtropical island with low population pressure and a largely unchanged natural landscape. Accordingly, a great geodiversity of volcanic morphologies and erosion processes has been preserved. In addition, half of the land is protected as a Biosphere Reserve and as a UNESCO Global Geopark, and the island is pursuing energy self-sufficiency. Local tourism is a sustainable activity, as the main attractions are either diving or hiking through the island’s various volcanic landscapes. Covering these and other aspects, and using accessible language, the book will appeal to scientists specialized in geotourism, active leisure entrepreneurs, and members of the general public interested in volcanic geoheritage and geotourism

El Hierro Island Global Geopark

This open access book explores El Hierro Island, which is geologically the youngest of the Canary Islands (Spain). Having registered its latest volcanic eruption in 2011-2012, it is an oceanic subtropical island with low population pressure and a largely unchanged natural landscape. Accordingly, a great geodiversity of volcanic morphologies and erosion processes has been preserved. In addition, half of the land is protected as a Biosphere Reserve and as a UNESCO Global Geopark, and the island is pursuing energy self-sufficiency. Local tourism is a sustainable activity, as the main attractions are either diving or hiking through the island’s various volcanic landscapes. Covering these and other aspects, and using accessible language, the book will appeal to scientists specialized in geotourism, active leisure entrepreneurs, and members of the general public interested in volcanic geoheritage and geotourism

Natural Disasters in Latin America and the Caribbean: An Overview of Risk

Escrito como resenha do livro "A nova razão do mundo: ensaio sobre a sociedade neoliberal" organizado por Pierre Dardot e Christian Laval. DARDOT, Pierre; LAVAL, Christian. A nova razão do mundo: ensaio sobre a sociedade neoliberal. Tradução Mariana Echalar. São Paulo: Boitempo, 2016

Natural Disasters in Latin America and the Caribbean: An Overview of Risk

This paper integrates information from both economics and the physical sciences to survey the effects of natural disasters in the region. A first section surveys the human and economic impact of natural disasters in the region at both the household and aggregate levels, noting both the geographical distribution of disaster risk and its long-term implications for development. A second section reviews types of disasters prevalent in the region, and future disaster risks, as well as the socio-economic sources of vulnerability to disasters resulting from development and migration patterns. A third section discusses risk management strategies at the household and community level, with public policy options and proposals for emergency response and finding an appropriate mix of local, national and market-based solutions.

Combining experimental volcanology, petrology and geophysical monitoring techniques

In general, an understanding of the complex processes acting before and during volcanic eruptions is approached from various different sides, e.g. laboratory experiments on fragmentation and/or bubble burst eruption mechanisms, petrological analysis of the eruptive products and various geophysical monitoring and source localization techniques. Each of these techniques can deliver valuable insights by adding pieces of information about the physical processes that drive the volcanic activity. However, often studies are focussing on a single aspect of the process, without setting the results in a more general context. Often, this strategy is absolutely valid, when the focus is laid on a single piece in the complex chain of processes taking place in volcanic eruptions. This must fail when the results aim to suggest a valid model for the combined observations at volcanoes using the above described techniques. The resulting models of volcanic source mechanisms and eruptive features can therefore lead to biased assumptions. This study aims to close this gap between laboratory experiments, petro-chemical analysis and modern geophysical monitoring and source localization techniques in a case study of Mt. Yasur (Vanuatu) volcano. The presented laboratory experiments on explosive volcanic eruptions upon rapid decompression show that decompression rate is the dening parameter in the experiments and that a scaling to large-scale processes is valid. Furthermore, a model is presented that correlates measured particle velocities to decompression rate and initial gas-overpressure. This model is used to estimate source volumes and overpressures at Volcan de Colima (Mexico) and Mt. Yasur (Vanuatu). A petrographically and geochemically characterization of Mt. Yasurs eruptive products suggests a shallow magma-mingling process at both of Mt. Yasurs active craters, perhaps due to rejuvenation of material slumped from the crater walls into an open conduit system. A study on the time-reversal imaging technique and its ability to detect the details of finite rupture (or time-variant) processes shows that the limitations of TR imaging start where the source stops being point-localised with respect to the used wavelength. Inversion of the source mechanisms of Strombolian explosions at Mt. Yasur are performed using a multi-parameter dataset consisting of seismic, acoustic and Doppler-radar data. Time-reversal imaging and moment tensor inversion are used to invert the source location of the seismic long-period (f < 1Hz) signals, which is supposed to refl ect fluid movement at depth. The source is located in the north-east of the crater region in a depth of several hundred meters. Furthermore, the source volume of the radiated infrasound signals is estimated from fundamental resonance frequencies. The results showed that the maximum particle velocity measured with the Doppler radar correlates nicely with the estimated source volumes lengths. The inverted seismic moment does not show any correlation with the estimated slug sizes, i.e. the slug size does not map in seismic moment. This is an important information, as it states that a larger source volume does not necessarily produces a larger seismic moment. From these combined results, a common feeder system for all active craters at Mt. Yasur is proposed. The differences in event recurrence rate at the three active craters are believed to be controlled by either the conduit geometry or variations in degassing or cooling rate. Strombolian-type eruptions at Mt. Yasur are suggested to be due to the burst of gas slugs with lengths and overpressures comparable to volcanoes showing similar eruptive patterns. The results illustrate the importance of combined studies that overcome the limitations of single disciplines. In this way, a more comprehensive view of volcanic eruptions and the associated observations is possible. Such a multi-disciplinary approach will contribute to a better understanding of volcanic processes and the associated hazards