Seismic expressions of shallow gas in the lacustrine deposits of Lake Balaton, Hungary

F. Visnovitz, T. Bodnár, Z. Tóth, V. Spiess, I. Kudó, G. Timár, F. Horváth

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Lake Balaton, a large shallow lake in Central Europe (Hungary), has been the site of extensive ultrahigh- resolution acoustic and multichannel seismic profiling in the period of 1997-2013. These surveys showed the widespread occurrence of shallow gas in the lake sediments and their immediate substrata. We analyzed about 2000 km of two-dimensional profiles and mapped the different gas occurrences in the uppermost 20 m. The anomalies caused by free gas were identified, classified, and assigned to upper, middle and lower levels based on gas signatures and stratigraphic position. Monitoring of the uppermost gas front has revealed temporal variations between surveys from different years and seasons that manifested in the changes of free gas content in the upper two levels. Free gas in the lower part of the lake sediments and at around the base of the mud indicated greater stability. The different nature of the three free gas levels can be explained by vertical changes in quantity, production rate, and solubility of methane and carbon dioxide gases. We suggest that methane was derived from the microbial decomposition of organic matter in the mud and Pleistocene peat at the base of the mud, whereas CO2 is transported to the lower mud layers by upwelling fluids.

Original languageEnglish
Pages (from-to)433-446
Number of pages14
JournalNear Surface Geophysics
Volume13
Issue number5
DOIs
Publication statusPublished - Oct 1 2015

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Hungary
lakes
lacustrine deposit
deposits
lake
mud
gases
gas
sediments
methane
occurrences
peat
Central Europe
upwelling water
dioxides
carbon dioxide
upwelling
solubility
temporal variation
acoustics

ASJC Scopus subject areas

  • Geophysics

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Seismic expressions of shallow gas in the lacustrine deposits of Lake Balaton, Hungary. / Visnovitz, F.; Bodnár, T.; Tóth, Z.; Spiess, V.; Kudó, I.; Timár, G.; Horváth, F.

In: Near Surface Geophysics, Vol. 13, No. 5, 01.10.2015, p. 433-446.

Research output: Contribution to journalArticle

Visnovitz, F. ; Bodnár, T. ; Tóth, Z. ; Spiess, V. ; Kudó, I. ; Timár, G. ; Horváth, F. / Seismic expressions of shallow gas in the lacustrine deposits of Lake Balaton, Hungary. In: Near Surface Geophysics. 2015 ; Vol. 13, No. 5. pp. 433-446.
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