Detecting Near-shore Submarine Permafrost at Barrow, Alaska Using Electrical Resistivity

• Main Authors: Overduin, Pier Paul, Westermann, Sebastian, Haberlau, T., Romanovsky, V., Yoshikawa, K.
• Format: Conference Object
• Language: unknown
• Published: 2010
• Subjects: Arctic; Sion; Barrier Islands; Barrow; Ice; permafrost; Alaska
• Online Access: https://epic.awi.de/id/eprint/22773/; https://hdl.handle.net/10013/epic.35470

Non-consolidated sections of the arctic coastline are generally rich in ground ice and highly dynamic due to the combined effects of thermal abrasion and ero-sion. Subsidence following thaw may contribute to shaping shore-face profile and speed erosion, analo-gous to the removal of material in the near-shore zone. Ice dynamics in the near shore are thus impor-tant to coastal erosion rates. We test electrical resis-tivity tomography as a means of measuring the depth of ice-bearing permafrost within the sediment and to gain insights into how sediment ice content may control coastal dynamics. Coastline position change rate studies at Elson Lagoon at Barrow, USA, pro-vide background information on long-term coastal evolution as far back as the end of the 19th century. We couple observations on change in coastal geo-morphology with geophysical observations along a submarine sub-bottom profile obtained using electri-cal resistivity soundings and drilling. Permafrost on the land-side of the coastline at Elson Lagoon (71° 18' N , 156° 32' W) is ice-rich near the ground surface. It is cold at Barrow (about -9 °C at 20 m, the depth of zero seasonal amplitude) and warmed by about 2°C during the last century. De-spite sheltering by barrier islands, coastal retreat rates on the western and southern coasts of the la-goon have been high over the past few decades. Permafrost evolution after inundation following coastal retreat was examined using a combination of electrical resistivity surveys, sediment sampling and temperature measurements. Sub-bottom apparent electrical resistivity was collected in the summer of 2008 using an IRIS Syscal Pro(TM) system and an electrode cable with 5 m spacing. A GPS and echo-sounder measured position and bathymetry. In spring 2009, 4 boreholes were drilled along 2 tran-sects at 1 and 2.25 m water depth. Borehole tem-peratures, sediment pore water salinity and stable isotope composition were measured. Over twenty offshore profiles were measured with a penetration depth of about 15 m. Resistivity ...