DSpace Community: 02. Cryosphere

Glacio RADAR system and results

Sun, 25 May 2008 22:58:59 GMT

Title: Glacio RADAR system and results

Authors: Zirizzotti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Baskaradas, J. A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Bianchi, C.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Sciacca, U.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia; Tabacco, I. E.; Università di Milano/ Dipartimento scienza della terra, Via Cicognara 7 20129 Milano Italy; Zuccheretti, E.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia

Editors: IEEE Aerospace and Electronics Systems Society, (AESS); IEEE Aerospace and Electronics Systems Society

Abstract: Since 1997 the Istituto Nazionale di Geofisica e Vulcanologia (INGV) in Italy has been involved in the development of the airborne RES system named Glacio RADAR, which is continuously upgraded. Radio Echo Sounding (RES) techniques are widely used in glaciological measurements. They are based on the use of radar systems, to obtain information concerning ice thickness of ice sheets and ice shelves, internal layering of glaciers, detection of inhomogeneities, exploration of subglacial lakes and identification of physical nature of subglacial interface. The Glacio RADAR is mounted on an aircraft and flies at an altitude around 300m above the ice surface during the survey. The first prototype operates in bistatic mode with separate transmit and receive one wire folded dipole installed beneath the aircraft wings. It works at 60 MHz with an envelope pulse width variable between 0.3 s and 1 s. The receiving window is 64 s which implies a maximum penetration depth (range) in the ice of about 5.3 km. The horizontal sampling rate is 10 traces/s at a mean aircraft speed of about 70 m/s. This would produce roughly 143 traces per kilometre (horizontal resolution of 1 trace every 7 m). The Navigation and geographical information is based on a on board GPS receiver giving longitude, latitude, altitude and time for the acquired radar trace. This radar was used in several Italian Antarctic Expeditions (1997, 1999, 2001 and 2003) and highlights of data results from these expeditions are presented here.

Glacio RADAR system and results

Sun, 25 May 2008 22:58:59 GMT

Sedimentation and aspects of glacial dynamics from physical properties, mineralogy and magnetic properties at ODP Sites 1166 and 1167, Prydz Bay, Antarctica

Mon, 29 Oct 2007 22:58:59 GMT

Title: Sedimentation and aspects of glacial dynamics from physical properties, mineralogy and magnetic properties at ODP Sites 1166 and 1167, Prydz Bay, Antarctica

Authors: Forsberg, C. F.; Norwegian Geotechnical Institute, P.O. Box 3930 Ullevaal Stadion, N-0806 Oslo, Norway; Florindo, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Grützner, J.; University of Bremen,; Venuti, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; Solheim, A.; Norwegian Geotechnical Institute, P.O. Box 3930 Ullevaal Stadion, N-0806 Oslo, Norway

Abstract: Trough mouth fans are formed by aggradation of glacial debris flows from sediment deposited by fast flowing ice streams extending to the shelf edge. We here present investigations at two sites, ODP Site 1166 on the shelf and ODP Site 1167 drilled on the Prydz Channel Fan in order to contribute to the understanding of Neogene ice flow patterns in Prydz Bay. The mineralogy, wt.% > 63 μm, physical and magnetic properties were analyzed. The mineralogy of Neogene strata at Site 1166 can be correlated to nearby ODP Site 742 drilled during Leg 119. Moreover an increase in the shear strength of the sediments (Leg 119 load event 3) is found both at Site 1166 and Site 742. This load event probably indicates that the oldest glacial configuration involved thicker glaciers than the later ones. The results from Site 1167 show that there has been a significant change in the provenance of the sediments during the past 2 million years. The greatest change occurred at about 1.13 Ma and implies a shift in the glacial configuration in Prydz Bay with a greater contribution of material from western parts of the drainage basin during the deposition of Unit II (> 1.13 Ma; 217–435 mbsf) at Site 1167 on the Prydz Channel Fan.

grid_strain and grid_strain3: software packages for strain field computation in 2D and 3D environment

Sat, 22 Sep 2007 22:58:59 GMT

Title: grid_strain and grid_strain3: software packages for strain field computation in 2D and 3D environment

Authors: Teza, G.; Geoscienze, Università Padova; Pesci, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Bologna; Galgaro, A.; Geoscienze, Università Padova

Abstract: Two MatlabTM software packages for strain field computation, starting from displacements of experimental points (EPs), are here presented. In particular, grid_strain estimates the strain on the nodes of a regular planar grid, whereas grid_strain3 operates on the points of a digital terrain model (DTM). In both cases, the computations are performed in a modified least square approach, emphasizing the effects of nearest points. This approach allows users to operate at different scales of analysis by introducing a scale factor to reduce or also exclude too far points from grid nodes. The input data are displacements (or velocities) that can be provided by several techniques (e.g. GPS, total topographical station, terrestrial laser scanner). The analysis can be applied to both regional- and local-scale phenomena, to study tectonic crustal deformations or rapid landslide collapses, and to characterize the kinematics of the studied system. Errors on strains and geometric significance of the results are also provided.