Developing a new, passive diffusion sampling array to detect helium anomalies associated with volcanic unrest

Bulletin of Volcanology
By: , and 

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Abstract

Helium (He) concentration and 3 He/ 4 He anomalies in soil gas and spring water are potentially powerful tools for investigating hydrothermal circulation associated with volca- nism and could perhaps serve as part of a hazards warning system. However, in operational practice, He and other gases are often sampled only after volcanic unrest is detected by other means. A new passive diffusion sampler suite, intended to be collected after the onset of unrest, has been developed and tested as a relatively low-cost method of determining He- isotope composition pre- and post-unrest. The samplers, each with a distinct equilibration time, passively record He concen- tration and isotope ratio in springs and soil gas. Once collected and analyzed, the He concentrations in the samplers are used to deconvolve the time history of the He concentration and the 3 He/ 4 He ratio at the collection site. The current suite consisting of three samplers is sufficient to deconvolve both the magnitude and the timing of a step change in in situ con- centration if the suite is collected within 100 h of the change. The effects of temperature and prolonged deployment on the suite ’ s capability of recording He anomalies have also been evaluated. The suite has captured a significant 3 He/ 4 He soil gas anomaly at Horseshoe Lake near Mammoth Lakes, California. The passive diffusion sampler suite appears to be an accurate and affordable alternative for determining He anomalies associated with volcanic unrest.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Developing a new, passive diffusion sampling array to detect helium anomalies associated with volcanic unrest
Series title Bulletin of Volcanology
DOI 10.1007/s00445-015-0912-4
Volume 77
Issue 3
Year Published 2015
Language English
Publisher Springer
Contributing office(s) National Research Program - Western Branch
Description Article 23; 17 p.
Online Only (Y/N) N
Additional Online Files (Y/N) N