What is below the water masses? Multibeam studies of Öskjuvatn, Thingvallavatn and Kleifarvatn

• Main Author: Árni Friðriksson 1990-
• Other Authors: Háskóli Íslands
• Format: Thesis
• Language: English
• Published: 2014
• Subjects: Jarðfræði; Dýptarmælingar; Botnrannsóknir; Öskjuvatn; Kleifarvatn; Þingvallavatn; Kongsberg; Vatnið; Vötn
• Online Access: http://hdl.handle.net/1946/18548

Multibeam echo sounding systems are used worldwide to survey ocean floors, ship canals and lake floors. They transmit pulses of acoustic waves at various frequencies into the water and listen to the returning echoes. Most systems record both bathymetry and the strength of the returning echoes (backscatter intensity). Three Icelandic lakes, Öskjuvatn, Kleifarvatn and Thingvallavatn, are all situated in volcanological environment. Their surroundings have been studied extensively but lack of high-resolution bathymetric data has limited the possibility of studying the lake floors. In June and September 2012 and November 2013 Kleifarvatn, Öskjuvatn and the SW-part of Thingvallavatn respectively, were surveyed with a Simrad EM3002 high-resolution multibeam echo sounder from Kongsberg Maritime. The results of these surveys are three bathymetric maps with 2 m horizontal resolution and 10 m contours, three backscatter intensity maps with 2 m horizontal resolution and three generalized geologic maps of the surveyed areas. Three craters, or cones, five lava flows, six solfataras and massive landslides were observed underwater in the Öskjuvatn caldera. Numerous faults, volcanic deposits and lava flow fronts were observed in SW-Thingvallavatn. However, no geothermal activity was recorded in the survey area. Four volcanic ridges, six solfataras and numerous faults, all of which aligned in a similar manner to regional topography, were observed on the lake floor of Kleifarvatn. Fjölgeisla bergmálsdýptarmælar eru notaðir út um allan heim til mælinga á höfum, í skipaskurðum og á stöðuvötnum. Þeir senda hljóðbylgjur niður í vatnið og hlusta svo eftir endurköstum frá botninum eða hlutum í vatninu. Flestir fjölgeisla bergmálsdýptarmælar safna og vista bæði dýptarmælingar og styrk endurkastanna frá hljóðbylgjunum. Rannsóknarsvæðin voru þrjú vötn í eldvirku umhverfi, Öskjuvatn, Kleifarvatn og suðvesturhluti Þingvallavatns. Mælingar fóru fram á Kleifarvatni í júní 2012, Öskjuvatni í september 2012 og Þingvallavatni í nóvember 2013. ...