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Hydrothermal alteration was analyzed in the active Turrialba Volcano, Central Volcanic Range, Costa Rica. Principal component analysis (PCA) techniques were applied to Thematic Mapper (1986 and 2001) and MODIS/ASTER airborne imagery (2003). Analyses were carried out using 4 input bands in PCA transformations to detect clays and iron oxides. The tec...
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... is known as Turrialba 'graben'. It has some particular features, such as: (1) three conserved craters -Northeastern, Central and Southwestern-at the almost flat summit, (2) one collapsed crater at the southwestern-most margin of the summit, and (3) two pyroclastic cones, El Armado and Tiendilla, which are built over Ariete Stream fault. (Fig. 2). According to Soto (1988), Turrialba 'graben' seems to have a length of 11 km, including two stratovolcanoes emplaced in the same NE-trending as Turrialba's craters (Finca Liebres at the SW and Dos Novillos). A great avalanches amphitheatre (2.5 km-wide and 3.5 km-length) enhances the physiographic ex- pression because it is limited by ...
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Hydrothermal alteration was analyzed in the active Turrialba Volcano, Central Volcanic Range, Costa Rica. Principal component analysis (PCA) techniques were applied to Thematic Mapper (1986 and 2001) and MODIS/ ASTER airborne imagery (2003). Analyses were carried out using 4 input bands in PCA transformations to detect clays and iron oxides. The te...
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Citations
... Along these mountain ranges there are many hot springs (Alvarado & Vargas, 2017;Bundschuch et al., 2007). These have been analyzed mostly in relation to their volcanic activity (Bragado-Massa et al., 2014), but ...
We used the 16S rRNA gene pyrosequencing approach to investigate the microbial diversity and community composition in several Costa Rican hot springs alongside the latitudinal axis of the country, with a range of temperatures (37–63°C), pH (6–7.5) and other geochemical conditions. A principal component analyses of the physicochemical parameters showed the samples were separated into three geochemically distinct habitats associated with the location (North, Central, and South). Cyanobacteria and Chloroflexi comprised 93% of the classified community, the former being the most abundant phylum in all samples except for Rocas Calientes 1, (63°C, pH 6), where Chloroflexi and Deinococcus‐Thermus represented 84% of the OTUs. Chloroflexi were more abundant as temperature increased. Proteobacteria, Bacteriodetes and Deinococcus‐Thermus comprised 5% of the OTUs represented. Other Phyla were present in very small percentages (<1%). A LINKTREE analysis showed that the community structure of the mats was shaped primarily by pH, separating samples with pH > 6.6 from samples with pH < 6.4. Thus, both pH and temperature were relevant for community composition even within the moderate ranges of variables studied. These results provide a basis for an understanding of the physicochemical influences in moderately thermophilic microbial mats. In this work we describe the diversity of microbial mats in hot springs at different temperatures and geographical locations in Costa Rica, using high throughput sequencing methods in order to answer questions about the combined potential influence of pH and temperature on bacterial communities.
The Turrialba Volcano is a stratovolcano located approximately 35 km northwest from San José, Costa Rica’s capital city. Since October 29, 2014, until at least late 2015, a series of eruptions has represented the most significant activity of this volcano since the 1860s. These eruptions dispersed a significant volume of ash that reached the most populous areas of the country. In this article, the characteristics of the ash particles are analyzed in order to establish the nature of the eruptive events that occurred on 2014 and 2015, and to monitor the evolution of the eruptive processes. The analysis was carried out utilizing optical microscopy and stereomicroscopy techniques, as well as novel scanning electron microscopy (SEM) methods that involve imaging and element composition analysis by means of Energy Dispersive X-Ray Spectroscopy (EDX). Results show the evolution of the Turrialba eruptions from phreatic events in 2014, with ashes composed entirely of non-juvenile fragments, to phreatomagmatic events starting on March 12, 2015 with the appearance of a significant fraction of juvenile components in the ash.
