Fumarole migration and fluid geochemistry at Poás Volcano (Costa Rica) from 1998 to 2001

Abstract

We report the results of a geochemical survey of fumaroles, thermal springs, and gas discharges from areas in and around the active crater lake of Pofis volcano (Costa Rica) fi'om February 1998 to February 2001. The springs are highly acidic-sulphate waters with temperatures approaching boiling point, whereas gas chemistry is characterized by typical magmatic species, such as 802, HF, HC1, H2, and CO. From February 1998 new fumarolic fields formed inside the southern part of the crater. They moved anticlockwise from the S to the NE inner walls of the crater, while those located in the southern part of the crater and close to the pyroclastic cone south of the crater lake diminished or disappeared altogether, during 1999 and 2000. This shift was also characterized by chemical variation of the maganatic gas species. In spite of the chemical changes of fumaroles, the composition of the lake changed little during this time. This fact, together with the chemical profile with depth of the lake, suggests that the lake is a very efficient condenser of magmatic fluids. An apparent chemical stratification of the lake suggests that dilution with meteoric water is not complete, due to the presence of liquid sulphur at the lake bottom and/or due to the continuous influx of new magmatic components.

Emisión difusa de CO2 y actividad volcánica en el volcán Poás, Costa Rica

“…Así mismo, en el sector E del área de estudio y en el borde norte del cráter principal se midieron valores altos de flujo de CO 2 (>600 g m -2 d -1 ). Vaselli et al (2003) reportan para el periodo 1999 y 2000 un aumento en el contenido de cloruros de los condensados fumarólicos, sugiriendo la existencia de un aumento en la liberación de fluidos del sistema hidrotermal. Los cambios observados en la composición química de las fumarolas del Poás es el primer estado de los cambios que serán observados en las emisiones difusas del Poás en los años sucesivos.…”

Thermal and geochemical signature of Poás Volcano, Costa Rica (MARCH 2009)

“…9). As suggested by Vaselli et al (2003), the lake SO 2 flux, similar to that emitted by the dome, might result from poor efficiency of the shallow hydrothermal system in condensing magmatic components, i.e. SO 2 and HCl, promoting vigorous sulphur release.…”

“…The lake size, level, temperature and composition are not only controlled by seasonal effects and hydrological features, but also by volcanic activity Martínez et al, 2000;Ramírez et al, 2010). The tracking of parameters such as temperature (Oppenheimer, 1993;Vaselli et al, 2003;Mora et al, 2004;Trunk & Bernard, 2008), water composition (Rowe et al, 1992b;zimmer et al, 2004), plume chemistry (Pfeffer et al, 2006), seismicity (Casertano et al, 1987), ground deformation (Rymer et al, 2000), and gravimetry (e.g., Rymer & Brown, 1989) have been critical for the assessment of magma intrusion, and thus for civil protection purposes, especially after the 1953-55 and the 1980s eruptive episodes, which caused severe damage to the local environment and agriculture (Rymer et al, 2005). Additionally, gases emitted by the volcano may result in significant impacts on human health (e.g., Oppenheimer, 1992;Hansell & Oppenheimer, 2004).…”

Volcano–hydrothermal system of Ebeko volcano, Paramushir, Kuril Islands: Geochemistry and solute fluxes of magmatic chlorine and sulfur

“…A ternary diagram in Fig. 3 shows relative concentrations of CO 2 , S t (total sulfur, SO 2 + H 2 S) and HCl for Ebeko fumarolic gases and compares those with the composition of high HCl gases (N 97°C) at Poas volcano (Costa Rica) based on the data reported at the Volcanic Gas workshop in 2003(Newsletter, 2006. See also Fischer et al, 2015).…”

“…The diagram shows that vapor separated from acidic chloride solution contains high HCl and the concentration of HCl becomes similar to that of high-temperature volcanic (magmatic) vapors (e.g., Taran and Zelenski, 2014). We believe that this is the case for Ebeko, as well as for the Poas low-temperature fumaroles (Rowe et al, 1992;Vaselli et al, 2003;Fischer et al, 2015). The presence a ) The gas content for Well P2 (mmol/mol) was calculated using Ar concentration following the method described in Taran (2005).…”