Reliable Floating Accumulation Chamber method for measuring CO2 emissions from volcanic crater lakes
Abstract
Temporal variations in CO2 fluxes can be related to changes in the volcanic activity and may be important for the mitigation of the volcanic risk. On the recorded eruptions from 73 volcanoes hosting a lake some of them had devastating consequences on inhabited areas surrounding the volcanoes as the 1919 Kelud (Indonesia) eruption that killed 5160 people. Lake water contributed largely to the devastating lahars surrounding the volcano area. In order to measure CO2 flux from crater lakes it is necessary to measure fluxes at the water lake surface. CO2 degassing through the lake surface occurs by bubbling (convective /advective degassing) and diffusion through the water/air interface. CO2 flux survey on the surface of lakes has been performed by using the floating accumulation chamber method. With the CO2 flux measured at several sites that covered the entire lake the CO2 emission rate is quantified from the studying lake. This survey can be repeated to see any change in the CO2 degassing from the volcanic lake. Moreover, the CO2 flux surveys can give insight into the local structures present locally or regionally. In 2011, a CO2 flux campaign was performed on Lake Rotomahana, New Zealand. Lake Rotomahana was formed during the 1886 Mt. Tarawera eruption along a 17 km long fracture between Mt Tarawera and Waimangu. Pre-1886, there were two small lakes in the area occupied by present-day Lake Rotomahana. Violent phreatic and phreatomagmatic eruptions deepened and enlarged the two small lakes to form the Rotomahana Crater, now filled to a depth of ~125 m forming a lake five times larger. Today thermal activity occurs mainly along the western shore of the lake with intense bubbling areas occurring in the lake close to these geothermal manifestations. The mean CO2 flux calculated by sequential Gaussian simulation from the lake was 57 ± 5.7 g/m2/day with total emission of 549 ± 72 t/day. The mapping of the CO2 flux over the lake and the sublacustrine bottom vents detected during the survey highlighted the craters formed during the 1886 eruption.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.V52B..03M
- Keywords:
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- 8419 VOLCANOLOGY / Volcano monitoring;
- 8424 VOLCANOLOGY / Hydrothermal systems;
- 8430 VOLCANOLOGY / Volcanic gases