Marine Geophysics

Relitti altomedievale di barca a fondo piatto rinvenuto nel canale Passaora, isola di Sant'Erasmo, laguna nord di Venezia,

by Alberto Lezziero

Published in "Archeologia Veneta", XXXII - 2009

Combinations of volcanic-flank and seafloor-sediment failure offshore Montserrat, and their implications for tsunami generation

by Mark Vardy

Co-authored with: S.F.L. Watt, P.J. Talling, V. Heller, V. Huhnerbach, M. Urlab, S. Sarkar, D.G. Masson, T.J. Henstock, T.A. Minshull, M. Paulatto, A. Le Friant, E. Lebas, C. Berndt, G.J. Crutchley, J. Karstens, A.J. Stinton, and F. Maeno

Recent seafloor mapping around volcanic islands shows that submarine landslide deposits are common and widespread.... more Recent seafloor mapping around volcanic islands shows that submarine landslide deposits are common and widespread. Such landslides may cause devastating tsunamis, but accurate assessment of tsunami hazard relies on understanding failure processes and sources. Here we use high-resolution geophysical data offshore from Montserrat, in the Lesser Antilles, to show that landslides around volcanic islands may involve two fundamentally different sources of sediment (island-flank and larger seafloor-sediment failures), and can occur in multiple stages. A combination of these processes produces elongate deposits, with a blocky centre (associated with island-flank collapse), surrounded by a smoother-surfaced deposit that is dominated by failed seafloor sediment. The failure of seafloor sediment is associated with little marginal accumulation, and involves only limited downslope motion. Submarine landslide deposits with similar blocky and smooth- surfaced associations are observed in several locations worldwide, but the complex emplacement processes implied by this morphological relationship can only be revealed by high-resolution geophysical data. Such complexity shows that the volume of landslide deposits offshore of volcanic islands cannot simply be used in tsunami models to reflect a single-stage collapse of primary volcanic material. By applying predictive equations for tsunami amplitude to investigate general scenarios of volcanic island landslide generation, we show that the tsunami hazard associated with volcanic island collapse remains highly significant. Volcanic flank failures, even if relatively small, may generate large local tsunamis, but associated seafloor sediment failures, even if they have a much greater volume, have a substantially lower potential for tsunami generation.

Between the Lines: Enhancing methodologies for the exploration of extensive inundated palaeolandscapes, In D. Cowley (ed.) Remote Sensing for Archaeological Heritage Management. Occasional Publication of the Aerial Archaeology Research Group No. 3, 173-205.

by Ben Gearey

co-authored with S. Fitch, V. Gaffney and E. Ramsey

In recent years there has been an increasing appreciation of the archaeological potential of European coastal shelves.... more In recent years there has been an increasing appreciation of the archaeological potential of European coastal shelves. This interest has not, however, simply been associated with the progress of traditional maritime history but rather the development of a wider marine archaeology aimed at exploring the settlement and cultural sequences of the immense, prehistoric landscapes that lie off some of our coasts. Inaccessible until quite recently, the development of a variety of remote sensing technologies has made exploration of these inhospitable landscapes a real possibility. The information that is being provided from such work is fundamentally changing our perception of the archaeology of the Palaeolithic and Mesolithic. This paper discusses the application of legacy seismic data to map these palaeolandscapes and contrasts the value of 2D and 3D data for these purposes. The results of new research in the North Sea and off the west coast of the United Kingdom are presented and used to test wide sampling strategies that have the potential to explore areas of the sea that have not been mapped using 3D technologies. The paper argues that a range of prospection strategies should be employed within these environments and that they should be optimised to support specific research goals. In the light of marine development and current economic uncertainty, the paper argues that heritage curators and researchers must take full advantage of data sets that have cost billions to capture and that provide unparalleled opportunities for research and management.

3D seismic analysis of high-amplitude anomalies in the shallow subsurface of the Northern Indus Fan: sedimentary and/or fluid origin

by Peter Clift

Landscape signatures and seabed characterisation in the marine environment of northwest Qatar

by Richard Cuttler

Al-Naimi F. A., Cuttler, R., Alhaidous, I. I., Momber, G., Al Naimi, S., Breeze, P. and Al Kawari, A. A.  Forthcoming, 2012 

Proceedings of the Seminar for Arabian Studies 42.

The Arabian Gulf is a fairly shallow sea and during the Last Glacial Maximum was an open landscape that may have... more The Arabian Gulf is a fairly shallow sea and during the Last Glacial Maximum was an open landscape that may have formed a refugia for human groups. The discovery of archaeological remains predating 8,000 years ago in the marine areas of the North Sea and English Channel would suggest that the Arabian Gulf also has a similar potential for the favorable survival of pre-marine transgression deposits. In addition, The Gulf has been part of a maritime trade network which extends back into the 7th millennium and so the region has the potential for shipwrecks from both the historic and prehistoric periods. However, despite this very little maritime archaeological research directed towards the discovery of such remains has been undertaken. Given the expense and logistical issues associated with diving and underwater survey this may not be entirely surprising. To survey the marine areas of Qatar alone using a team of divers would take many years, particularly given strong regional currents and limited visibility. In recent years the rapid development of geophysics has provided new opportunities to investigate wider areas of the marine landscape and to develop strategies for targeted diver inspections of geophysical anomalies.

The analysis of a large tract of geophysical data off the northwest coast of Qatar revealed more than 80 anomalies with a sea bed expression, some of which were clearly modern, and others that were considered to have reasonable archaeological potential. Of the anomalies subject to subsequent diver inspection, none proved to be of archaeological interest. However, the visual inspection of geophysical anomalies is providing valuable regional baseline data for the interpretation of anthropogenic marine signatures. The clarification of signatures from different types of anomalies enables the calibration of regionally important geophysical data. In addition, these inspections have significantly increased our understanding of the seabed characteristics around Northeastern Qatar. Future geophysical survey will be focused not simply on anomalies but on characterising the submerged landscape using higher resolution geophysical data from a range of sensors.

Tectonic erosion of the Peruvian forearc, Lima Basin, by subduction and Nazca Ridge collision

by Peter Clift

Beverly Goodman, Eduard Reinhardt, Hendrik Dey, Vasıf Şahoğlu, Hayat Erkanal, and Michal Artzy, Evidence for Holocene Marine Transgression and Shoreline Progradation due to Barrier Development in Iskele, Bay of Izmir, Turkey Journal of Coastal Research vol. 24, No: 5, 2008, 1269-1280.

by Vasıf Şahoğlu