Wojciech CZUBA, Marek GRAD, Aleksander GUTERCH, Mariusz MAJDAŃSKI, Michał MALINOWSKI, Rolf MJELDE, Mateusz MOSKALIK, Piotr ŚRODA, Monika WILDE−PIÓRKO  and Yuichi NISHIMURA

Seismic crustal structure along the deep transect Horsted’05, Svalbard

 Polish Polar Research 29 (3), 2008: 279-290

ABSTRACT: During the Polish−Norwegian−Japanese Polar Expedition in August 2005 a deep seismic sounding of the Earth’s crust was performed in the southern Svalbard area. It was an introduction to the international Cluster Program 77: Plate Tectonics and Polar Gateways in Earth History, closely related to the International Polar Year. During the expedition onboard r/v Horyzont II, a seismic transect Horsted’05 along Hornsund and crossing Storfjorden and Edgeøya was performed. Seismic energy (provided by an airgun and TNT shots) was recorded by land (onshore) seismic stations and ocean bottom seismometers (OBS) deployed along the transect, resulting in high quality refracted and reflected P−waves record sections. Clear seismic records from airgun shots were obtained up to distances of 150 km at land stations and OBSs. TNT explosions were recorded along the whole transect length even up to distances of 300 km. The obtained 2−D seismic model is complicated in the western part which is located ~100 km east of Knipovich Ridge. The Moho shallows in this area up to 14 km, while beneath the Hornsund it dips down to 33 km. The eastern part of the model is characterized by simpler structure, with two layers in the upper crust Vp = 5.5–6 km/s and in the lower crust Vp = 6.1–6.2 km/s. There is no P−wave velocity higher than 6.5 km/s in the crust of the Storfjorden and Edgeøya area. The Moho depth varies between 26 and 31 km.

Key words: Arctic, Svalbard, Spitsbergen, seismic crustal structure.

Address:(1) Instytut Geofizyki, Polska Akademia Nauk, Księcia Janusza 64, 01−452 Warszawa, Poland wojt@igf.edu.pl mgrad@mimuw.edu.pl aguterch@igf.edu.pl mmajd@igf.fuw.edu.pl michalm@igf.edu.pl mmosk@igf.edu.pl; (2) Instytut Geofizyki, Uniwersytet Warszawski, Pasteura 7, 02−093 Warszawa, Poland mgrad@mimuw.edu.pl mwilde@igf.fuw.edu.pl; (3) Institute of Solid Earth Physics, University of Bergen, Post Box 7800, N−5020 Bergen, Norway Rolf.Mjelde@geo.uib.no; (4) Institute of Seismology and Volcanology, Hokkaido University, N10S8 Kita−ku Sapporo
060−0810, Japan nishi@eos.hokudai.ac.jp