El Chichón crater lake dynamic based on continuous physical data and mass-heat budget
Abstract
The March-April 1982 Plinian eruption of El Chichón volcano destroyed the summit domes system and created a new 200 m deep crater. Since then, a shallow lake (~3 m) with acidic pH (~2.3), and temperature around 30°C appeared in the crater. This lake has never disappeared until now although its volume has suffered important variations from 40,000 m3 to 160,000 m3. Chemical composition of the lake is also highly variable (Cl/SO4 = 0-79 molar ratio), alternating between acid-sulfate and acid-chloride-sulfate composition. These variations can occur very fast within few weeks and are not directly correlated with precipitation. Due to its shallow depth and small volume, El Chichón crater lake is probably one of the most dynamic crater lake on earth. These rapid changes in chemistry and volume reflect the dynamic of one group of geyser-type springs ('Soap Pools springs, SP') located offshore and the input of hydrothermal steam underneath the crater. The SP springs discharge sporadically to the lake neutral waters with Cl content currently around 3000 mg/l, while the condensed steam feeds the lake with Cl-free and SO4-rich acid water. In this study, we present for the first time continuous physical data of the crater lake (temperature, depth, meteoric precipitation, wind velocity, solar radiation, air humidity). These data were registered by a meteorological station and two dataloggers installed inside and outside the lake. Using a mass and heat budget model constrained with these data, we were able to estimate the flux of 'hydrothermal' fluid entering the lake through the sub-lacustrian fumaroles and SP springs. Tracing the variations of the input flux in time can be help to understand the dynamic of the 'crater lake-SP springs-fumaroles' system but also can provide an efficient way of monitoring the volcanic activity. During the observation period, the mean mass flux entering the lake (Min) was respectively of 12 ± 2 kg/s, corresponding to a total heat flux (Ein) of 154 ± 23 W/m2. However, exceptional events of precipitation and evaporation can affect the 'equilibrium' state of the lake and cause some temporary fluctuations in the Min and Ein values. We also evaluated the mean mass fluxes lost by evaporation (Mev) and seepage (Ms), as well as the input by precipitation (Mr). The estimated values for the Mev, Ms y Mr parameters were respectively of 8 ± 2 kg/s, 10 ± 1.5 y 16 ± 2 kg/s. This data set constitutes a baseline to monitor the future activity of El Chichón volcano.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFM.V53A2596P
- Keywords:
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- 8419 VOLCANOLOGY / Volcano monitoring;
- 8424 VOLCANOLOGY / Hydrothermal systems