Abstract
Springs at La Soufrière of Guadeloupe have been monitored for nearly four decades since the phreatic eruption and associated seismic activity in 1976. We conceptualize degassing vapor/gas mixtures as square-wave sources of chloride and heat and apply a new semianalytic solution to demonstrate that chloride and heat pulses with the same timing and duration result in good matches between measured and simulated spring temperatures and concentrations. While the concentration of chloride pulses is variable, the local boiling temperature of 96°C was assigned to all thermal pulses. Because chloride is a conservative tracer, chloride breakthrough is only affected by one-dimensional advection and dispersion. The thermal tracer is damped and lagged relative to chloride due to conductive heat exchange with the overlying and underlying strata. Joint analysis of temperature and chloride allows estimation of the onset and duration of degassing pulses, refining the chronology of recent magmatic intrusion.
| Original language | English |
|---|---|
| Pages (from-to) | 3068-3076 |
| Number of pages | 9 |
| Journal | Geophysical Research Letters |
| Volume | 45 |
| Issue number | 7 |
| DOIs | |
| State | Published - Apr 16 2018 |
| Externally published | Yes |
Funding
The authors thank Chi-Yuen Wang and Benoit Villemant for their helpful review comments. Seismic data, temperature, and chemical spring monthly data were collected by OVSG-IPGP team since 1978. The monthly temperature and Cl data of CE, Ga, and CC springs between 1979 and 1992 are provided in the supporting information (Table S3). Funding for Erick R. Burns was provided by the U.S. Department of Energy Geothermal Technologies Program (EERE award number DE-EE0007169), the USGS Energy Resources Program, and the USGS Water Availability and Use Science Program.
Keywords
- heat transport
- magma degassing
- volcanic hydrothermal system