Seismic Research in the Thinia valley

2022 Fieldwork Report

We have been able to carry out a huge amount of important fieldwork in 2022 due to the generous support of our donors. If you donated, thank you. If this report and the information you can find on this website prompts you to support the Odysseus Unbound project, click here for details of how you can help.

The 2022 fieldwork was planned to be closely focussed on making a final determination of the fundamental “island hypothesis”: that Paliki was a separate island in the Late Bronze Age, the time of Odysseus.

Seismic surveys of the Thinia valley

In May, we welcomed teams from Uppsala University in Sweden and the Politecnico di Torino in Italy, who joined our long-time collaborator, Professor George Apostolopoulos of the National Technical University of Athens, to carry out seismic and gravity surveys across the Thinia valley.

  • For our seismic surveys, up to 200 geophones were laid in long lines to listen for seismic waves refracted and reflected through the geology beneath...

  • The vibrations that travel through the rocks were made with a heavy drop hammer...

  • ...or sometimes in a more traditional way!

  • Seismic data picked up by the geophones generates images like this that then have to be expertly analysed.

The aim was to image deep cross-sections of the valley right down to sea level and below, to look for evidence of the former marine channel that we propose existed along the valley in the Late Bronze Age.

No signs of the channel remain on the surface. Any evidence for it is buried within the complex geology of the valley subsurface.

Previous ERT surveys and boreholes have given us a good understanding of the sub-surface structure down to some 165 metres but the seismic data should give us further clues about the geology of the valley to a depth of 300m or more, well below today’s sea level.

It may even able to identify remnants of the channel sides.

Active and passive seismic measurements

Two different seismic techniques were used. Active seismic data collection generates an image of the subsurface in great detail but to a limited depth due to the small seismic sources used. Passive seismic “sees” much deeper, but in less detail.

Map of seismic lines
The three active seismic arrays (coloured lines), the passive seismic array (dark blue stars), and the gravity stations (yellow spots), with the Fugro borehole positions (green circles with yellow pins), superimposed on a Google Earth image of the Thinia valley. (Image: George Apostolopoulos, NTUA)

Professor Alireza Malehmir (Uppsala University) discusses the Active Seismic method

Professor Valentia Socco (Politecnico di Torino) describes the Passive Seismic method

Combining the data from both techniques with the lithological data from several boreholes drilled by FUGRO in the Thinia valley over ten years ago will give us our best possible understanding of the valley structure.

OSL dating

Dr Jean-Luc Schwenninger came to Kefalonia in October to collect samples for OSL analysis in his Luminescence Dating laboratory at Oxford University to help us determine when the landslip that closed the channel happened.

Dr Jean-Luc Schwenninger explains the OSL technique.

Optically Stimulated Luminescence (OSL) reveals the date when a sediment sample was buried by discovering when it was last exposed to sunlight.

2022 fieldwork - OSL Trench

Two trenches were dug near what we call the “wooded triangle”, a tree-covered area at the southern end of the Thinia valley, where landslip material has splashed over the bedrock on the western side of the valley and buried ancient walls.

The trenches lie on the western end of the southern seismic profile (pink line in Google Earth image, above) which ties the dates obtained to the deposition and tectonic movement of the wider area.

View of the "wooded triangle"
Looking west across the southern end of the Thina valley towards the “wooded triangle”
2022 fieldwork - obtaining an OSL Sample
Dr Jean-Luc Schwenninger collecting a sediment sample for OSL dating.

Jean-Luc collected samples from within the trenches at different depths which should give us the date for when the walls were buried.

Marine fossils at southern exit

Also in October, Professor Maria Triantaphyllou, a micro-palaeontologist from the National and Kapodistrian University of Athens, surveyed and took surface samples from the southern exit of the Thinia valley.

John and Maria field walk the southern exit of the Thinia valley
Professors John Underhill and Maria Triantaphyllou field walk the southern exit of the Thinia valley
2022 fieldwork - Professor Maria Triantaphyllou collects a sediment sample
Professor Maria Triantaphyllou collects a sediment sample

Here, on the edge of the massive landslip that we suggest closed the marine channel, though still uplifted by some 30 or 40 metres, the channel is likely to have been much less damaged.

2022 fieldwork - Professor Maria Triantaphyllou collects a sediment sample
Professor Maria Triantaphyllou collects a sediment sample
2022 fieldwork - the sample is bagged
The sample is bagged for transport to the laboratory

While any obvious surface evidence for the channel has been eroded, today’s surface sediments may still have originated from the channel floor. If they did, they will contain marine micro-fossils deposited when the sediments lay at the bottom of the channel.

Maria will examine her samples under an electron microscope in her lab in Athens to identify any micro-fossils.

Finding such micro-fossils at that height above sea level would be significant evidence that a marine channel once existed.

Bronze Age tomb site excavations

This year we continued our close collaboration with the Ephorate of Antiquities of Kefalonia, the Greek government archaeologists on the island.

Excavations at a known Mycenaean site on Paliki produced further tantalising clues that this was a significant area of human occupation in the Late Bronze Age.

Results expected in early 2023

A huge amount of data has been collected in 2022 and it will take time to analyse and understand it all properly.

Our grateful thanks go to all the scientists who have generously given their time and expertise.

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