FN Archimer Export Format PT J TI Microevents produced by gas migration and expulsion at the seabed: a study based on sea bottom recordings from the Sea of Marmara BT AF TARY, Jean-Baptiste GELI, Louis GUENNOU, Claude HENRY, Pierre SULTAN, Nabil CAGATAY, N. VIDAL, V. AS 1:1;2:1;3:5;4:2;5:1;6:3;7:4; FF 1:;2:PDG-REM-GM;3:;4:;5:PDG-REM-GM-LES;6:;7:; C1 IFREMER, Dept Marine Geosci, F-29280 Plouzane, France. Aix Marseille Univ, CEREGE, CNRS, UMR 6635, F-13545 Aix En Provence 4, France. Istanbul Tech Univ, Min Fac, Dept Geol, TR-34469 Istanbul, Turkey. Univ Lyon, Phys Lab, Ecole Normale Super Lyon, CNRS, F-69364 Lyon 07, France. Univ Western Brittany, UMR 6538, European Inst Marine Studies IUEM, F-29280 Plouzane, France. C2 IFREMER, FRANCE UNIV AIX MARSEILLE, FRANCE UNIV TECH ISTANBUL, TURKEY UNIV LYON, FRANCE UBO, FRANCE SI BREST SE PDG-REM-GM PDG-REM-GM-LES IN WOS Ifremer jusqu'en 2018 copubli-france copubli-univ-france copubli-int-hors-europe copubli-sud IF 2.85 TC 24 UR https://archimer.ifremer.fr/doc/00089/20012/17825.pdf LA English DT Article CR MARMARASCARPS MARMESONET MARNAUT BO L'Atalante Le SuroƮt DE ;Time series analysis;Gas and hydrate systems;Body waves;Interface waves;Seismic attenuation;Wave propagation AB Different types of 4-component ocean bottom seismometers (OBS) were deployed for variable durations ranging from 1 week to about 4 months in 2007, over soft sediments covering the seafloor of the Tekirdag Basin (western part of the Sea of Marmara, Turkey). Non-seismic microevents were recorded by the geophones, but generally not by the hydrophones, except when the hydrophone is located less than a few tens of centimetres above the seafloor. The microevents are characterized by short durations of less than 0.8 s, by frequencies ranging between 4 and 30 Hz, and by highly variable amplitudes. In addition, no correlation between OBSs was observed, except for two OBSs, located 10 m apart. Interestingly, a swarm of similar to 400 very similar microevents (based on principal component analysis) was recorded in less than one day by an OBS located in the close vicinity of an active, gas-prone fault cutting through the upper sedimentary layers. The presence of gas in superficial sediments, together with analogies with laboratory experiments, suggest that gas migration followed by the collapse of fluid-filled cavities or conduits could be the source of the observed microevents. This work shows that OBSs may provide valuable information to improve our understanding of natural degassing processes from the seafloor. PY 2012 PD AUG SO Geophysical Journal International SN 0956-540X PU Wiley-blackwell VL 190 IS 2 UT 000306279100020 BP 993 EP 1007 DI 10.1111/j.1365-246X.2012.05533.x ID 20012 ER EF