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URI permanente para esta colecciónhttp://10.0.96.45:4000/handle/11056/24484

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International geosciences field research with undergraduate students: Three models for experiential learning projects investigating active tectonics of the Nicoya Peninsula, Costa Rica
(Geological Society of America, 2009) Marshall, Jeffrey S.; Gardner, Thomas W.; Protti, Marino; Nourse, Jonathan A.
International field experiences offer exceptional opportunities for effective student learning in the geosciences. Over the 10 yr period between 1998 and 2008, more than 40 undergraduate students from 14 institutions participated in fi eld research investigating active tectonics on the Nicoya Peninsula, Costa Rica. Three different project models were used: (1) a month-long summer research project, (2) a series of 1 to 2 wk independent field study projects, and (3) a week-long field research module. These projects shared a common research theme (active tectonics), field area (Nicoya Peninsula), and pedagogy (experiential learning), thus allowing for easy comparison of teaching methods, logistics, and learning outcomes. Each model has unique pedagogical benefits and challenges, and is therefore better suited for a different group size, student to faculty ratio, project duration, and budget. Collectively, these student research projects generated significant publishable data relevant to ongoing investigations of forearc tectonics and earthquake hazards along the Costa Rican Pacific margin. Individual student projects were carefully designed to provide a quality field learning experience, while adding a new piece to the larger research puzzle. Indicators of project success include levels of student engagement; gains in technical and cognitive field skills; and productivity of student-authored publications, reports, and presentations. Students commonly described these projects as instrumental in shaping their professional identity as geoscientists. Blending international field research with experiential learning pedagogy creates a powerful synergy that captures student imagination and motivates learning. By placing students beyond the comfort of their home learning environment, inter national field projects pique student curiosity, sharpen awareness and comprehension, and amplify the desire to learn. Experiential learning pedagogy encourages students to define their own research agenda and solve problems through critical thinking, inquiry, and reflection. The potent combination of international fieldwork and experiential learning helps students to develop the self-confidence and reasoning skills needed to solve multifaceted real-world problems, and provides exceptional training for graduate school and professional careers in the geosciences.
Volcano Seismology: Detecting Unrest in Wiggly Lines
(Springer Science and Business Media Deutschland GmbH, 2019) Salvage, Rebecca; Karl, Sandra.; Neuberg, Jourgen. W.
Seismology is a useful tool to gain a better understanding of volcanic unrest in real time as it unfolds. The generation of seismic signals in a volcanic environment has been linked to a number of different physical processes occurring at depth, including fracturing of the volcanic edifice (producing high frequency seismicity) and movement of magmatic fluids (producing low frequency seismicity). Further classification of seismic signals according to their waveform similarity, in addition to their frequency content, allows greater detail in temporal and spatial changes of seismicity to be detected. At Soufrière Hills volcano, Montserrat, one of the target volcanoes of the VUELCO project, families of similar waveforms provided valuable insight into evaluating the significance of ongoing unrest. In June 1997 over 6000 more events were able to be identified over a 5 day period of interest (22 to 25 June) by using families of seismic events, rather than a standard amplitude-based detection algorithm. In total, 11 families were identified, with the events clustering into a number of swarms, suggesting a repeating and non destructive cyclic source mechanism. Since each family is believed to represent a distinct source location and mechanism, identifying 11 coexisting families reflects the complex diversity of physical processes which act simultaneous at this volcano. In July 2003, conditions at the volcano had clearly changed since only one family of seismicity was identified. The source location of this family appeared to shift with time from 8 July (when no events from the family were identified) to 12 July (where most events had a cross correlation coefficient over 0.9). In addition, the use of families appears to greatly aid hindsight forecasting attempts for the large scale dome collapses of 1997 and 2003 using the Failure Forecast Method. Knowledge of the temporal and spatial extent of seismicity during periods of unrest, its source mechanism and its relationship to physical processes at depth is essential for decision and policy makers for risk mitigation. However, the source mechanisms of such volcanic seismicity is still much debated and appears to often be misinterpreted because of compromising assumptions used in the numerical modelling of inverting such sources. Use of a spatially extended source such as a ring fault structure, rather than a single point for determining the origin of low frequency seismicity, is now thought to be more realistic for the mechanism of such events since it more accurately represents the movement of magma through a conduit. However, use of this spatially extended source instead of a simple single point results in a large underestimation of slip from P-wave amplitudes, which may lead to an underestimation in magma ascent rates, with large consequences for eruption forecasting. Additionally, the P-wave radiation patterns exhibited by these two mechanisms are remarkably similar, and can only be distinguished if the small radial radiation lobes can be determined. In a volcanic environment this is extremely difficult due to large uncertainties in earthquake source depth locations, and the implementation of small aperture seismic networks

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Examinando Capítulo de libro por Materia "SEISMOLOGY"