TITLE:
A Mega-Tsunami in the Baltic Sea 1171 BC: Geological Records with Special Reference to the Lake Mälaren Area in Sweden
AUTHORS:
Nils-Axel Mörner, Björn Ambrosiani, Phyllis Anderson Ambrosiani
KEYWORDS:
Tsunami Deposits, Mega-Tsunami, Wave Height and Run-Up, Kaali Impact, Archaeological Reinterpretations, The Bronze Age, Lake Mälaren Area, Sweden
JOURNAL NAME:
International Journal of Geosciences,
Vol.11 No.10,
October
30,
2020
ABSTRACT: At about
3000 C14-year BP or 1200 cal. yrs BC, the Baltic Sea experienced a mega-tsunami
with a wave-height of 10 m or more, and a run-up height of up to 16.5 m. This
event had significant geological and archaeological effects. We explore the
records from the Lake M?laren area in Sweden. The tsunami event is linked to
seismic ground shaking and methane venting tectonics at several sites. The
triggering factor is proposed to be the Kaali meteor impact in Estonia of the
same age. The documentation of a mega-tsunami in the middle of the Bronze Age
has wide implications both in geology and in archaeology. The archaeological
key sites at Annelund and Apalle are reinterpreted in terms of tsunami wave
actions remodelling stratigraphy. By extensive coring, we are able to trace the
tsunami effects in both off-shore and on-shore environment. At the time of the
event, sea level was at +15 m (due to isostatic uplift). The tsunami wave
erosion is traced 13.5 m below sea level. The tsunami run-up over land is
traced to +29.5 m to +31.5 m (occasionally even higher), implying a run-up of
14.5 - 16.5 m. In ?ngermanland, the
tsunami event was absolutely dated at 1171 varve years BC. Archaeologically, the tsunami event coincides
well with the transition between Periods II and III of the South Scandinavian
Bronze Age. Period III has traditionally been difficult to identify in the
cultural materials of the Lake M?laren region.