Corinth Virtual Site Survey: Integrating Geophysical Data for Syn-rift Stratigraphy, Fault and Basin Evolution and Advancing IODP Proposed Drilling

Lead Research Organisation: University of Southampton
Department Name: School of Ocean and Earth Science

Abstract

The breaking apart of a continent to form extended continental margins and ultimately ocean basins is a process that can last for 10s of millions of years. The start of this process of rifting is thought to contribute significantly to the structure and sedimentary layering of the continental margins that have formed by its end. Often the details of how rifting initiates and develops in the first few million years are lost in the complexities of deformation and thick sediment layers beneath the continent's edges. To understand the early phases, we have to study areas where rifting has only recently started, and the Gulf of Corinth, Greece, is a key example in its first few millions of years of history. Across the Gulf, the two sides of the rift are moving apart at up to 20 mm every year and this high rate of extension results in numerous earthquakes which historically have been very destructive. The rapid extension also results in a rapidly developing rift basin which is partially submerged beneath the sea and filling with sediments.
Within the Gulf, a large volume of marine geophysical data has been collected, including detailed maps of the seabed, as well as seismic data that use sound sources to give cross-sections of material beneath the seabed. The seismic data allow us to directly image the accumulated sediment layers and to identify faults that offset the layers and create the basin. This project will integrate these data to make a very detailed interpretation of the sediment layers (and their likely age) and fault planes. Imaging and assigning ages to the layers, by comparing with models of climate and sea level change, allows us to determine how the basin has developed through time. The fault planes imaged by the data generate the extension and subsidence of the rift, and their history of activity controls how the basin develops. The results will be used to generate the first high resolution model of rift development over the initial few million years of a rift's history and will help to address some of the unanswered questions of how continents break apart. The model will be used by a range of scientists, including those trying to understand how tectonics, landscape morphology and climate all interact to cause sediments to move from one place to another: rift basins are one of the main sinks for sediments and we will calculate how the volume of sediment delivered to the Corinth basin has changed with time, as faults move and as climate changes.
The majority of the world's petroleum resources are found in old rifts, but often details of how the rift developed and the detailed geometry of the rock units in which the oil is now found are masked by other geological processes and by shallower sediment layers. Understanding the early rift processes is important for determining where and what kind of sediments will be deposited in different parts of the basin with time. We will also analyse details of how individual faults grow and interact with other faults in the rift: this process affects where sediments enter a rift basin and is therefore also important for identifying petroleum reservoirs.
The rift faults are responsible for the destructive earthquakes in central Greece, so this project's analysis of fault location and rate of slip will also help us to better understand the potential hazard, increasing the potential for reduction of associated risk.
Ultimately, the project will be used to select sites for drilling and sampling the sediments of the rift zone, through the Integrated Ocean Drilling Program. These samples would provide: the actual age of sediment layers, and hence well resolved slip rates for each active fault and a test for the rift models generated here; and the types of sediments, that will tell us more about the regional climate of the last few millions of years and where sediments that typically form hydrocarbon reservoirs are located in this analogue for older rift systems like the North Sea.

Planned Impact

The primary non-academic beneficiaries of the proposed project's results will be the petroleum industry (and hence indirectly UK natural resources and their economic impact), the risk assessment and mitigation communities within Greece (including policy makers), Greek and tourist communities impacted by geohazards associated with the Corinth rift, the natural hazard Insurance sector, the general public (through outreach) and local education communities.
Petroleum Resources:
Results will be of direct relevance to petroleum reservoir and trap development in syn-rift settings and therefore of interest to the hydrocarbon industry. The high resolution analysis of sediment distribution in the context of fault and basin growth within a developing rift system, an end product of this project, is directly applicable to hydrocarbon exploration, contributing to assessments of potential reservoir units within syn-rift stage sediments in older hydrocarbon-bearing basins, such as the North Sea. With the expiration of hydrocarbon systems within shallower fields, the petroleum industry are increasingly interested in exploration of deeper stratigraphic levels within the syn-rift phase and the use of modern analogues, such as the Corinth rift, improves knowledge of the likely structure and stratigraphy of these deeper plays. Within this project, we will develop an existing collaboration between Bell (PDRA2) and the petroleum industry (named collaborator: Dr Ben Clements, North Sea Regional team, Statoil, with expertise in large scale rift development), enabling direct engagement with industry.
Geohazards:
This project will refine active fault maps, fault activity history and slip rates (ultimately constrained through drilling) for the Corinth rift, Greece. These results are of direct relevance to seismic hazard assessment and mitigation within Greece. Extension and strain rates in the study area are some of the highest in the world, and the region is one of the most seismically active in Europe, with a long history of destructive earthquakes and secondary tsunami and landslides. The region has high population densities in cities and coastal regions, and is a popular tourist destination. Therefore understanding of potential hazards is critical for improving risk management and mitigation in central Greece. Assessment of these hazards will also impact the wider European population, through tourism, and the Insurance sector. Results will be used to feed into hazard zonation mapping in central Greece and probabilistic seismic hazard assessment and peak ground acceleration models. Through our Project Partners in Greece (including Hellenic Centre for Marine Research (HCMR) and National Observatory Athens (NOA), both national laboratories), we have direct links to government offices and regional civic protection agencies with remits for evaluating seismic risk.
Outreach and Education:
The societal relevance of hydrocarbon resources and geohazards is clear, and this project will therefore be of interest to the wider community. We plan to engage with communities, both in the UK, and through Partners, in Greece, by participation in outreach activities and by interaction with local schools, capitalising on existing links and activities. Participation in general outreach activities (e.g., the annual National Science Week Ocean and Earth Day at Southampton) during the project will deepen the understanding of plate tectonics and why rifting of the Earth's lithosphere is a critical process in the generation of the Earth's natural resources (hydrocarbons) and in controlling natural hazards. Through direct interaction with local school children (PDRA working with a Southampton University Student Ambassador), delivery of the science curriculum will be enhanced by showing how modern research techniques are used to maximise Earth's resources, understand and mitigate against natural hazards, and to deepen our understanding of the plate tectonic process.

Publications

10 25 50
 
Description The details of how a rift has developed in its earliest history at very high resolution, i.e. at 10,000s of years timescale and km's spatial scale. This involves details of fault activity and how these faults influence for the formation of a basin and how sediments then fill that basin.
Exploitation Route The primary results are now published within a journal article in Tectonics. The results have also been presented at several international conferences. Several other publications are in preparation.
The results have been used to submit a proposal for drilling within the Corinth rift - this proposal was rated excellent, went forward for scheduling, and the expedition (IODP 381) took place in October-December, 2017 and February 2018. The expedition was extremely successful, in large part as a result of this grant/project.
Sectors Energy,Environment

 
Description Drilling has now taken place, in part as a result of this grant/project. A new chronology is being developed for the syn-rift stratigraphy and material gathered for further dating. These will be used to update fault slip rates and these will then be incorporated into regional earthquake hazard maps and planning. We will work with Greek partners to ensure this happens.
Sector Environment
Impact Types Societal,Economic

 
Description Corinth Rift Drilling Workshop - Magellan ECORD Funding
Amount € 14,980 (EUR)
Organisation European Consortium for Ocean Research Drilling (ECORD) 
Sector Public
Country European Union (EU)
Start 10/2013 
End 07/2014
 
Title Corinth rift fault and stratigraphic horizon and seismic reflection database 
Description Integrated database of all seismic reflection data within the Corinth Rift, Greece Complete integrated interpretation of all faults and syn-rift stratigraphic horizons within the offshore rift Complete and full fault map for the Corinth rift system 
Type Of Material Database/Collection of data 
Year Produced 2014 
Provided To Others? Yes  
Impact We are just completing the integration process and therefore envision wider distribution of the database over the next few years. This is and will be used for new PhD student projects in UK, Norway and Greece. The database will also be passed to partners in Greece for integration into regional natural hazards/earthquake hazard assessment databases. The database has now been provided to NGDC for archiving and availability to the wider community. 
 
Description Collaborations between UK, Greece, Norway, France, and US partners in preparation of IODP ocean drilling proposal for drilling in the Corinth rift 
Organisation Hellenic Centre for Marine Research (HCMR)
Country Greece 
Sector Public 
PI Contribution Hosting research workshop in Greece, February 2014 Successful submission of ocean drilling proposal to IODP, October 2014 Planning for ocean drilling IODP expedition 381, to take place in 2017
Collaborator Contribution Workshop hosting and support, data contributions for proposal, and intellectual input to proposal
Impact Ocean drilling workshop report for EOS (AGU publication) and ECORD (European Ocean Drilling)
Start Year 2012
 
Description Corinth rift ocean drilling workshop, Athens, Greece 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact The workshop brought together 25-30 key international scientists working in the Corinth rift and in active rift zones globally to a) determine key global rifting science questions and b) address how these can be tackled through drilling within the Corinth rift.
The workshop resulted in submission of an IODP proposal for drilling in the Corinth rift in October, 2014

As yet no direct impacts, but successful drilling would be high profile in Greece (for the public as well as scientific community) and will provide extremely valuable fault slip and earthquake potential data (input to regional earthquake hazard assessment) from within the rift system.
Year(s) Of Engagement Activity 2014
 
Description Major National Oceanography Centre Southampton Open Day: Ocean and Earth Day, 2014 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact ~3000 members of the public of all ages visit during the Open Day. Display and discussion provided about plate tectonics and earthquake and volcanic hazards.

No specific impacts related to this part of the event but questionnaires completed by the public for the overall event indicating specific impact
Year(s) Of Engagement Activity 2014