Possible earthquake trigger for 6th century mass wasting deposit at Lake Ohrid (Macedonia/Albania)

B Wagner,H Vogel,R Sulpizio,G Daut,G Zanchetta,S Krastel,A Francke,S Trajanovski,K Lindhorst,B Lushaj,J Rethemeyer,A Grazhdani

doi:10.5194/cp-8-2069-2012

Abstract

Abstract. Lake Ohrid shared by the Republics of Albania and Macedonia is formed by a tectonically active graben within the south Balkans and suggested to be the oldest lake in Europe. Several studies have shown that the lake provides a valuable record of climatic and environmental changes and a distal tephrostratigraphic record of volcanic eruptions from Italy. Fault structures identified in seismic data demonstrate that sediments have also the potential to record tectonic activity in the region. Here, we provide an example of linking seismic and sedimentological information with tectonic activity and historical documents. Historical documents indicate that a major earthquake destroyed the city of Lychnidus (today: city of Ohrid) in the early 6th century AD. Multichannel seismic profiles, parametric sediment echosounder profiles, and a 10.08 m long sediment record from the western part of the lake indicate a 2 m thick mass wasting deposit, which is tentatively correlated with this earthquake. The mass wasting deposit is chronologically well constrained, as it directly overlays the AD 472/AD 512 tephra. Moreover, radiocarbon dates and cross correlation with other sediment sequences with similar geochemical characteristics of the Holocene indicate that the mass wasting event took place prior to the onset of the Medieval Warm Period, and is attributed it to one of the known earthquakes in the region in the early 6th century AD.

Highlights

Lake Ohrid (40◦54 –41◦10 N, 20◦38 –20◦48 E, Fig. 1) is a transboundary lake located on the Balkan Peninsula and shared between the Republics of Macedonia and Albania
A significant erosional unconformity at the base of MWD1 cannot be detected in the parametric sediment echosounder line at the coring location, probably because MWD1 pinches out only a few hundred meters to the east of the coring location and a potential erosion decreased with increasing distance from the steep slope (Fig. 3)
The Co1262 record shows the high potential of Lake Ohrid for paleoseismicity investigations, by combining seismic, sedimentological, climatic, tephrostratigraphic, and historical information

Summary

Introduction

Lake Ohrid (40◦54 –41◦10 N, 20◦38 –20◦48 E, Fig. 1) is a transboundary lake located on the Balkan Peninsula and shared between the Republics of Macedonia and Albania. The current lake level is at 693 m above sea level (a.s.l.) and the lake is surrounded by the Mokra Mountains to the west (1514 m a.s.l.) and the Galicica Mountains to the east (2265 m a.s.l.; Fig. 1)

Methods

Results

Conclusion