A tsunami is a series of waves in a body of water, which – instead of being generated by the wind or the gravitational pull of the moon and the sun – are caused by the displacement of a large volume of water. Earthquakes, volcanic eruptions and other underwater explosions (including intentional detonations, landslides, meteorite impacts and other disturbances) above or below water can all cause devastating tsunamis. 

One of the worst in recent history was the one that occurred in 2004 under the Indian Ocean, when an earthquake caused huge damage on the coasts of Indonesia, Thailand, Sri Lanka, India and other countries.

Tsunamis are a relatively common event along the eastern Mediterranean coastline, with historical records and geographic data showing one tsunami occurring per century over the last 6,000 years. The record for earlier tsunami events, however, is less clear. Tsunami events in antiquity had a profound influence on coastal societies. Six thousand years of historical records, and geological data show that tsunamis are a common phenomenon affecting the eastern Mediterranean coastline. However, the possible impact of older

tsunamis on prehistoric societies has not been investigated.

Researchers at the department of marine geosciences at the University of Haifa; the Scripps Center for Marine Archaeology at the University of California at San Diego; the department of geosciences at Utah State University; and the Institute of Geophysics and Planetary Physics at the University California at Santa Cruz went back even farther. They describe in the prestigious journal PLoS (US Public Library of Science) a large early-Holocene tsunami deposit (between 9,910 to 9,290 years ago) in coastal sediments at Tel Dor in northwest Israel, a maritime city-mound occupied from the Middle Bronze II period (2000-1550 BCE) through the Crusader period.

To conduct their analysis, the authors used photogrammetric remote- sensing techniques to create a digital model of the Tel Dor site some 30 kilometers south of Haifa, combined with underwater excavation and terrestrial borehole drilling to a depth of nine meters.

Along the coast of the study area, the scientists found an abrupt marine shell and sand layer with an age of constraint 9,910 to 9,290 years ago, in the middle of a large ancient wetland layer spanning from 15,000 to 7,800 years ago. 

The journal article appears under the title “A Neolithic mega-tsunami event in the eastern Mediterranean: Prehistoric settlement vulnerability along the Carmel coast, Israel”  at https://doi.org/10.1371/journal.pone.0243619.

They estimated that the wave was capable of depositing seashells and sand in the middle of what was at the time fresh to brackish wetland must have travelled 1.5 to 3.5 kilometers, with a coastal wave height of 16 to 40 meters. For comparison, previously documented tsunami events in the eastern Mediterranean have travelled inland only around 300 meters — suggesting that the tsunami at Dor was generated by a far stronger mechanism. 

Local tsunamis tend to arise due to earthquakes in the Dead Sea Fault system and submarine landslides; the authors note that an earthquake contemporary to the Dor paleo-tsunami (dating to around 10,000 years ago) has already been identified using cave damage in the nearby Carmel ridge, suggesting this specific earthquake could have triggered an underwater landslide causing the massive tsunami at Dor.

This paleo-tsunami would have occurred during the Early to Middle Pre-Pottery Neolithic B cultural period of the regio, and potentially wiped out evidence of previous Natufian (12,500–12,000 years ago) and Pre-Pottery Neolithic coastal villages (previous surveys and excavations show a near absence of low-lying coastal villages in this region). The re-appearance of abundant Late Neolithic archaeological sites (about 6,000 BCE) along the coast in the years after the Dor tsunami coincides with the resumption of wetland deposition in the Dor core samples and indicates resettlement followed the event–highlighting residents’ resilience in the face of massive disruption. 

According to Gilad Shtienberg, an Israeli postdoctoral scholar at the Scripps Center for Marine Archaeology who is studying the sediment cores, “Our project focuses on reconstructing ancient climate and environmental change over the past 12,000 years along the Israeli coast; we never dreamed of finding evidence of a prehistoric tsunami in Israel.  Scholars know that at the beginning of the Neolithic Period around 10,000 years ago, the seashore was four kilometers from where it is today. When we cut the cores open in San Diego and started seeing a marine shell layer embedded in the dry Neolithic landscape, we knew we hit the jackpot.”