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Durham University

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Sea Level Research Unit (SLRU)

A research group of the Department of Geography.

SLRU, established in 1987, specialises in inter-disciplinary basic and applied research funded from a wide range of sponsors, including research councils, the European Union, the U.S. Geological Survey, conservation organisations, Government, business and commerce.

Sea Level Research Unit (SLRU) website

Our main research areas are:

Coastal Evolution

Much of this research addresses land-sea interactions in estuaries and deltas. We use a wide range of field and analytical methods to reconstruct coastal evolution over past millennia. In the UK our work includes the Thames, Tees, Humber, Fenland, Northumberland, Morecambe Bay and Solway Firth. The studies improve understanding of how estuaries responded to changes in relative sea level (heavily influenced by glacio-isostatic land uplift and subsidence), climate, sediment supply, geomorphology, tides and currents. In low latitudes regions where large estuaries and deltas exist, glacio-isostatic land movements are less important in controlling relative sea-level change, while variability of river discharge becomes influential in the evolution history of the coast. As a result, in addition to reconstructing local sea-level histories, in southeast and east Asia for example, monsoon-induced freshwater fluxes have been investigated using carbon isotope ratios. In some large deltas, such as the Yangtze Delta and the Pearl River Delta, a further dimension - human interaction with the environment - is also highly significant.

Selected Publications

  • Zong, Y. (2004). Mid-Holocene sea-level highstand along the southeast coast of China. Quaternary International, 117, 55-67.
  • Waller, M. P. and Long, A. J. (2003) Holocene coastal evolution and sea-level change on the southern coast of England: a review. Journal of Quaternary Science, 18, 351-359.
  • Long, A. J. (2003) The coastal strip: sea-level change, coastal evolution and land-ocean correlation. Progress in Physical Geography, 27, 455-466
  • Shennan, I., Coulthard, T., Flather, R., Horton, B., Macklin, M., Rees, J., and Wright, M. (2003). Integration of shelf evolution and river basin models to simulate Holocene sediment dynamics of the Humber Estuary during periods of sea-level change and variations in catchment sediment supply. The Science of The Total Environment, 314-316, 737-754.
  • Long, A. J. Hipkin, S. and Clarke, H. (2002). Romney Marsh: Coastal and Landscape Change Through the Ages. Oxford University School for Archaeology. 215 pp.
  • Shennan, I., and Andrews, J. E. (2000). Holocene land-ocean interaction and environmental change around the North Sea. Geological Society, Special Publications, 166, London.
  • Shennan, I., Horton, B. P., Innes, J. B., Gehrels, W. R., Lloyd, J. M., McArthur, J. J., and Rutherford, M. M. (2000). Late Quaternary sea-level changes, crustal movements and coastal evolution in Northumberland, UK. Journal of Quaternary Science, 15, 215-237.
  • Shennan, I., Lambeck, K., Flather, R., Horton, B. P., McArthur, J. J., Innes, J. B., Lloyd, J. M., Rutherford, M. M., and Wingfield, R. (2000). Modelling western North Sea palaeogeographies and tidal changes during the Holocene. In "Holocene land-ocean interaction and environmental change around the North Sea." (Shennan, I. and Andrews, J., Eds.), pp. 299-319. Geological Society, Special Publications, 166, London.
  • Zong, Y. and Tooley, M. J. (1999). Evidence of mid-Holocene storm-surge deposits from Morecambe Bay, northwest England: a biostratigraphical approach. Quaternary International, 55, 43-50.
  • Zong, Y. (1998). Diatom records and sedimentary responses to sea-level changes during the last 8000 years in Roudsea Wood, northwest England. The Holocene, 8, 219-228.
  • Lloyd, J. M., Shennan, I., Kirby, J. R., and Rutherford, M. M. (1999). Holocene relative sea-level changes in the inner Solway Firth. Quaternary International 60, 83-105.
  • Long, A. J., Innes, J. B., Kirby, J. R., Lloyd, J. M., Rutherford, M. M., Shennan, I., and Tooley, M. J. (1998). Holocene sea-level change and coastal evolution in the Humber estuary, eastern England: an assessment of rapid coastal change. The Holocene 8, 229-247.
  • Chen, X. and Zong, Y. (1998). Coastal erosion along the Changjiang deltaic shoreline, China: a perspective study. Estuarine, Coastal and Shelf Sciences, 46, 733-742.

Earthquake Hazards

This applied aspect of sea-level research utilises theory and methods of analysis developed at Durham during research in non-seismic locations to quantify relative land and sea-level changes resulting from great earthquakes, caused by inter-plate movements along segments of subduction zones, in Washington, Oregon and Alaska. One future aim is to extend this work to other plate-boundary locations around the Pacific and Indian Oceans.

The December 26 2005 plate-boundary earthquake off Indonesia, causing the devastating tsunami in the Indian Ocean, was of smaller magnitude than the 1964 great earthquake in Alaska. To help minimise loss from such catastrophes it is important to understand the mechanism and processes of great sub-marine earthquakes (magnitude ≥8.0) and associated tsunami. Future earthquake forecasting and reduction of loss require knowing the history of great earthquakes, including their frequency and how patterns of land movement vary during different earthquakes.

Recent research in Alaska, Washington and Oregon by the Sea Level Research Unit reveals that great plate-boundary earthquakes and tsunami hazards occur periodically over the past few thousand years, for example, eight in the last 5000 years in Washington. In Alaska we record six great earthquakes during the past 3300 years, at intervals that range from ~500 to ~900 years. In contrast to geodetic observations that are limited to the post-seismic phase since the 1964 earthquake, we quantify varying spatial patterns of uplift and subsidence through complete earthquake cycles. Relative land uplift characterises each inter-seismic phase of cycles, whereas each great earthquake had a precursor: a short period of pre-seismic relative land subsidence. Our analysis reveals a pre-seismic land subsidence or relative sea-level rise a common feature for at least 4 other late Holocene great earthquakes in Alaska and our current research focuses upon whether pre-seismic land subsidence represents a pre-cursor to great earthquakes.

Selected Publications

  • Hamilton, S., and Shennan, I. (2005). Late Holocene relative sea-level changes and the earthquake deformation cycle around upper Cook Inlet, Alaska. Quaternary Science Reviews, 24, 1479.
  • Hamilton, S., Shennan, I., Combellick, R., Mulholland, J., and Noble, C. (2005). Evidence for two great earthquakes at Anchorage, Alaska and implications for multiple great earthquakes through the Holocene. Quaternary Science Reviews, 24, 2050.
  • Hamilton, S. L., and Shennan, I. (2005). Late Holocene great earthquakes and relative sea-level change at Kenai, southern Alaska. Journal of Quaternary Science, 20, 95-111.
  • Zong, Y., Shennan, I., Combellick, R. A., Hamilton, S., and Rutherford, M. (2003). Microfossil evidence for land movements associated with the AD 1964 Alaska earthquake. The Holocene 13, 7-20.
  • Shennan, I., Scott, D. B., Rutherford, M. M., and Zong, Y. (1999). Microfossil analysis of sediments representing the 1964 earthquake, exposed at Girdwood Flats, Alaska, USA. Quaternary International, 60, 55-73.
  • Shennan, I., Long, A. J., Rutherford, M. M., Innes, J. B., Green, F. M., and Walker, K. J. (1998). Tidal marsh stratigraphy, sea-level change and large earthquakes--II: submergence events during the last 3500 years at netarts Bay, Oregon, USA. Quaternary Science Reviews, 17, 365-393.
  • Shennan, I., Long, A. J., Rutherford, M. M., Green, F. M., Innes, J. B., Lloyd, J. M., Zong, Y., and Walker, K. J. (1996). Tidal marsh stratigraphy, sea-level change and large earthquakes, i: a 5000 year record in washington, U.S.A. Quaternary Science Reviews, 15, 1023-1059.
  • Long, A. J., and Shennan, I. (1998). Models of rapid relative sea-level change in Washington and Oregon, USA. The Holocene, 8, 129-142.
  • Nelson, A. R., Shennan, I., and Long, A. J. (1996). Identifying coseismic subsidence in tidal-wetland stratigraphic sequences at the Cascadia subduction zone of western North America. Journal of Geophysical Research, 101, 6115-6135.
  • Long, A. J., and Shennan, I. (1994). Sea-level changes in Washington and Oregon and the 'earthquake deformation cycle'. Journal of Coastal Research, 10(4), 825-838.

Human Impacts and Coastal Hazards

This is an area of applied research of the Unit, ranging from coastal hazards to human impacts on coastal environment, targeting large low-lying coastal areas, often densely populated, in both developed and developing countries. Many of our projects analyse historical and modern records of storms, floods and tsunamis, whilst others develop Geographical Information Systems for cases studies to assess hazard vulnerability and preventive measures. Statistical analysis is also applied to predict potential impacts of future sea-level rise on coastal lowlands, lives and properties. Some results of our projects appear in academic journals while others directly inputs for policy makers such as the Environment Agency (UK), the Metropolitan Government of Shanghai, the US Geological Survey and the Bureau for Land Management, Alaska. Some projects are specifically designed to help industries such as insurance companies.

Selected Publications

  • Hamilton, S. L., and Shennan, I. (2005). Late Holocene great earthquakes and relative sea-level change at Kenai, southern Alaska. Journal of Quaternary Science, 20, 95-111.
  • Huang, Z., Zong, Y. and Zhang, W. (2004). Coastal inundation due to sea-level rise in the Pearl River delta. Natural Hazards, 33, 247-264.
  • Long, A. J., Bridgland, D. R., Innes, J. B., Mitchell M. R., and Vyner B. (2004). The Swale-Ure Washlands: Landscape History and Human Impacts. University of Durham, 24pp.
  • Cundy, A. B., Long, A. J., Hill, C. T., Spencer C., and Croudace I. W. (2002). Sedimentary response of Pagham Harbour, southern England to barrier breaching in AD 1910. Geomorphology, 46, 163-176
  • Papathoma M., Dominey-Howes D., Zong Y. and Smith D. (2003). Assessing tsunami vulnerability, an example from Herakleio, Crete. Natural Hazards and Earth System Sciences, 3, 377-389.
  • Zong, Y. and Tooley, M.J. (2003). Historical coastal floods in Britain: storm track patterns. Natural Hazards, 29, 13-36.
  • Chen, X., Zong, Y., Zhang, E., Xu, J. and Li, S. (2001). Human impacts on the Changjiang (Yangtze) River Basin, China, with special reference to the impacts on dry season water discharges into the sea. Geomorphology, 41, 111-123.
  • Zong, Y. and Chen, X. (2000). The 1998 flood on the Yangtze, China. Natural Hazards, 22, 165-184.
  • Zong, Y. and Chen, X. (1999). Typhoon hazards in the Shanghai area, China. Disasters, 23, 66-80.
  • Chen, X. and Zong, Y. (1999). Impacts of sea-level rise on agriculture in the Shanghai area, China. Applied Geography, 19, 69-84.
  • Chen, X. and Zong, Y. (1998). Coastal erosion along the Changjiang deltaic shoreline, China: a perspective study. Estuarine, Coastal and Shelf Sciences, 46, 733-742.
  • Zong, Y., Tooley, M. J. and Donoghue, D. M. N. (1995). Geographical Information Systems and sea flooding risk assessment in the Thames Lowlands. Journal of the Society of Fellows, 9, 3-18.
  • Shennan, I. (1993). Geographic information systems and future sea-level rise. In "Climate and Sea Level Change: observations, projections and implications." (Warrick, R. A., Barrow, E. M. and Wigley, T. M. L., Eds.), 215-228. Cambridge University Press, Cambridge.
  • Shennan, I. (1993). Sea-level changes and the threat of coastal inundation. The Geographical Journal, 159, 148-156.
  • Shennan, I. (1992). Impact of sea-level rise on the Wash. In "Impacts of sea-level rise on European coastal lowlands." (Tooley, M. J. and Jelgersma, S., Eds.), 72-93. Blackwell, Oxford.

Land Uplift and Subsidence

Much of this research derives from analyses of databanks of radiocarbon dated sea-level index points, first for the UK, initiated in 1980 and expanded as contributions to various International Geological Correlation Programme Projects.

First analyses, published 1987 and 1989, quantified the regional-scale pattern of uplift and subsidence around the North Sea and were followed, in the Journal of Quaternary Science for 1989, by the first analysis for 35 years to provide a quantitative estimate of current land uplift and subsidence in mainland Great Britain to be supported by both geological and oceanographic data. Significant advances in data quality and spatial cover followed over the next 10 years, culminating in the recent analysis (Shennan & Horton, 2002) that includes tidal range changes and anthropogenic-induced land subsidence.

Other analyses, Geophysical Journal International 1992, with an updated analysis in 1999, was the first from the United Kingdom to correlate the long-term geological trends and short-term tide gauge data, resulting in a quantitative estimate of the current absolute rate of sea-level rise. This indicated no evidence for an acceleration in the rate of rise, that could be expected to result from the enhanced greenhouse effect.

Recent work involves collaboration with geophysical modellers (Kurt Lambeck at ANU; Richard Peltier at Toronto; Glenn Milne at Durham) to expand and improve understanding of interactions between earth rheology, ice sheet histories and the global signals contained within the sea-level records from the UK.

Selected Publications

  • Shennan, I., and Horton, B. P. (2002). Holocene land- and sea-level changes in Great Britain. Journal of Quaternary Science, 17, 511-526.
  • Shennan, I., Peltier, W. R., Drummond, R., and Horton, B. (2002). Global to local scale parameters determining relative sea-level changes and the post-glacial isostatic adjustment of Great Britain. Quaternary Science Reviews, 21, 397-408.
  • Shennan, I., Lambeck, K., Horton, B. P., Innes, J. B., Lloyd, J. M., McArthur, J. J., Purcell, T., and Rutherford, M. M. (2000). Late Devensian and Holocene records of relative sea-level changes in northwest Scotland and their implications for glacio-hydro-isostatic modelling. Quaternary Science Reviews, 19, 1103-1136.
  • Woodworth, P. L., Tsimplis, M. N., Flather, R. A., and Shennan, I. (1999). A review of the trends observed in British Isles mean sea level data measured by tide gauges. Geophysical Journal International, 136, 651-670.

Late-Quaternary Sea-Level and Environmental Changes

Our research in this area develops and applies a wide range of methods of palaeo-environmental reconstruction (field, laboratory, microfossil, isotopic, experimental and analytical techniques) to understand earth/ ice sheet/ ocean/ sea level/ climate interactions since the Last Glacial Maximum. Much of the work involves high resolution relative sea-level reconstructions based on lake isolation data. These lakes were once below sea-level but have been uplifted from the sea by glacio-isostatic rebound. By coring them and examining their sediment for diatoms and other environmenatl proxies, it is possible to reconstruct the spatial and temporal pattern of uplift and deglacial history of a region. Recent projects include field locations in west and northwest Scotland, Greenland, Iceland and Norway (near-field locations). Other projects, in areas far away from the Last Glacial Maximum ice masses (far-field locations), also contribute to a better understanding of large scale sea-level change as well as local-scale coastal processes.

A combination of sea-level records from near-field and far-field locations, some covering more than 16,000 years, constrain global models of earth rheology and glacial history since the Last Glacial Maximum, providing quantitative limits on global meltwater discharge in terms of timing, magnitude and source.

Selected Publications

  • Shennan, I., Hamilton, S., Hillier, C., and Woodroffe, S. (2005). A 16 000-year record of near-field relative sea-level changes, northwest Scotland, United Kingdom. Quaternary International, 133-134, 95-106.
  • Zong, Y. and Hassan, K. B. (2004). Diatom assemblages from two mangrove tidal flats in peninsular Malaysia. Diatom Research, 19, 329-344.
  • Zong, Y. (2004). Mid-Holocene sea-level highstand along the Southeast Coast of China. Quaternary International, 117, 55-67.
  • Long, A. J., Roberts, D. H. and Rasch, M. (2003). The deglacial and relative sea-level history of Innaarsuit, Disko Bugt, West Greenland". Quaternary Research, 60, 162-171.
  • Shennan, I., and Milne, G. (2003). Sea-level observations around the Last Glacial Maximum from the Bonaparte Gulf, NW Australia. Quaternary Science Reviews, 22, 1543-1547.
  • Lloyd, J. M. and Evans, J. R. (2002). Contemporary and fossil foraminifera from isolation basins in northwest Scotland". Journal of Quaternary Science, 17, 431-443.
  • Shennan, I., Lambeck, K., Horton, B. P., Innes, J. B., Lloyd, J. M., McArthur, J. J., Purcell, T., and Rutherford, M. M. (2000). Late Devensian and Holocene records of relative sea-level changes in northwest Scotland and their implications for glacio-hydro-isostatic modelling. Quaternary Science Reviews, 19, 1103-1136.
  • Shennan, I., Lambeck, K., Horton, B. P., Innes, J. B., Lloyd, J. M., McArthur, J. J., and Rutherford, M. M. (2000). Holocene isostasy and relative sea-level changes on the east coast of England. In "Holocene land-ocean interaction and environmental change around the North Sea." (Shennan, I. and Andrews, J., Eds.), pp. 275-298. Geological Society, Special Publications, 166, London.
  • Long, A. J., Roberts D. H. and and Wright, M (1999). Isolation basin stratigraphy and Holocene relative sea-level change on Arveprinsen Ejland, Disko Bugt, West Greenland. Journal of Quaternary Science, 14, 323-345.
  • Lloyd, J. M., Shennan, I., Kirby, J. R., and Rutherford, M. M. (1999). Holocene relative sea-level changes in the inner Solway Firth. Quaternary International, 60, 83-105.

Research Areas

  • Coastal Evolution
  • Earthquake Hazard
  • Human Impacts and Coastal Hazards
  • Land Uplift and Subsidence
  • Late-Quaternary sea-level and environmental changes

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