Time-dependent CO variations in Lake Albano associated with seismic activity.

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Bibliographic Details
Title:	Time-dependent CO variations in Lake Albano associated with seismic activity.
Authors:	Chiodini, G.¹, Tassi, F. franco.tassi@unifi.it, Caliro, S.¹, Chiarabba, C.², Vaselli, O., Rouwet, D.³
Source:	Bulletin of Volcanology. May2012, Vol. 74 Issue 4, p861-871. 11p.
Subject Terms:	Crater lakes, Analytical geochemistry, Carbon, Earthquake zones
Geographic Terms:	Rome
Abstract:	Lake Albano (Alban Hills volcanic complex, Central Italy) is located in a densely populated area near Rome. The deep lake waters have significant dissolved CO concentrations, probably related to sub-lacustrine fluid discharges fed by a pressurized CO-rich reservoir. The analytical results of geochemical surveys carried out in 1989-2010 highlight the episodes of CO removal from the lake. The total mass of dissolved CO decreased from ∼5.8 × 10 kg in 1989 to ∼0.5 × 10 kg in 2010, following an exponential decreasing trend. Calculated values of both dissolved inorganic carbon and CO concentrations along the vertical profile of the lake indicate that this decrease is caused by CO release from the epilimnion, at depth <9 m, combined with (1) water circulation at depth <95 m and (2) CO diffusion from the deeper lake layers. According to this model, Lake Albano was affected by a large CO input that coincided with the last important seismic swarm at Alban Hills in 1989, suggesting an intimate relationship between the addition of deep-originated CO to the lake and seismic activity. In the case of a CO degassing event of an order of magnitude larger than the one that occurred in 1989, the deepest part of Lake Albano would become CO-saturated, resulting in conditions compatible with the occurrence of a gas outburst. These results reinforce the idea that a sudden CO input into the lake may cause the release of a dense gas cloud, presently representing the major volcanic threat for this densely populated area. [ABSTRACT FROM AUTHOR]
Database:	Energy & Power Source

Description
Abstract:	Lake Albano (Alban Hills volcanic complex, Central Italy) is located in a densely populated area near Rome. The deep lake waters have significant dissolved CO concentrations, probably related to sub-lacustrine fluid discharges fed by a pressurized CO-rich reservoir. The analytical results of geochemical surveys carried out in 1989-2010 highlight the episodes of CO removal from the lake. The total mass of dissolved CO decreased from ∼5.8 × 10 kg in 1989 to ∼0.5 × 10 kg in 2010, following an exponential decreasing trend. Calculated values of both dissolved inorganic carbon and CO concentrations along the vertical profile of the lake indicate that this decrease is caused by CO release from the epilimnion, at depth <9 m, combined with (1) water circulation at depth <95 m and (2) CO diffusion from the deeper lake layers. According to this model, Lake Albano was affected by a large CO input that coincided with the last important seismic swarm at Alban Hills in 1989, suggesting an intimate relationship between the addition of deep-originated CO to the lake and seismic activity. In the case of a CO degassing event of an order of magnitude larger than the one that occurred in 1989, the deepest part of Lake Albano would become CO-saturated, resulting in conditions compatible with the occurrence of a gas outburst. These results reinforce the idea that a sudden CO input into the lake may cause the release of a dense gas cloud, presently representing the major volcanic threat for this densely populated area. [ABSTRACT FROM AUTHOR]
ISSN:	02588900
DOI:	10.1007/s00445-011-0573-x