Quantitative lacustrine paleoseismology in Carinthia, Austria: improving the Environmental Seismic Intensity Scale and assessing strong earthquake recurrence in formerly-glaciated intraplate settings (Quake-Lake Carinthia)

Funded by the Austrian Science Fund (FWF) (09.2017-08.2021)

PI: Jasper Moernaut

Co-PI: Michael Strasser

Project Member: Christoph Daxer

Fog over Klopeiner SeeDespite being considered a country of moderate seismicity, several historical earthquakes in Austria caused massive impact on infrastructures and landscape.  Seismological data and historical records generally do not extend far enough back in time to make correct estimates of where and how often such catastrophic events could take place. It is possible that very strong earthquakes took place in prehistorical times and are thus overlooked in the present estimates of seismic hazard. As a consequence, future events may come with an “unexpected” large impact to (critical) infrastructure and excessive economic and human losses.    

We overcome this knowledge barrier by using lake sediments as natural seismometers. Strong earthquakes can deform lacustrine sediments and produce underwater landslides. Laminations of the Klopeiner SeeDue to the continuous accumulation of mud on the lake bottom, such evidence of past earthquakes gets preserved and can get retrieved by geophysical techniques and sampled by sediment cores. The Quake-Lake Carinthia project applies this paleoseismic research strategy on the large lakes in Carinthia, one of Austrias most seismic areas. Due to its unique setting −where many lakes have been impacted by several well-documented historical earthquakes− we determine relationships between the strength of shaking and the characteristics of the sedimentary features.  In this way, our records do not only show when strong earthquakes took place in the last 14.000 yrs, but also show how strong they were and in which area their epicenter was located. These long earthquake archives will also generate new insights about how earthquake activity changed over time as a consequence of the melting of the alpine icecap since the last Ice Age.   

The first core of the project arrives onboardPaleoseismological research is relatively new in Austria, and lake sediments as a natural earthquake archive have not been studied there. We implement and improve the newest methods in lacustrine paleoseismology: i) in-situ geotechnical tests to calculate how strong shaking needs to be to destabilize underwater slopes, ii) different geochemical and physical proxies to better understand the nature of the earthquake impact on lake sediments and surrounding landscapes.   

The detailed work on the Carinthian lakes forms the fundaments of a worldwide comparison of lake paleoseismology, where we evaluate how different sedimentary features in different lake systems can be used to reveal the shaking strength of past earthquakes. We combine present and new knowledge to construct a generic methodology which can be applied to improve seismic hazard assessments in many places worldwide.

Project Collaborators:

Karin Koinig (Institute of Ecology at University of Innsbruck)
Christa Hammerl (ZAMG - Central Institute for Meteorology and Geodynamics, Vienna)
Kurt Decker (University of Vienna)
Franz Neubauer (Salzburg University)
Marc De Batist (Ghent University, Belgium)
Achim Kopf (MARUM, Bremen, Germany)
Wolfgang Recheis (Innsbruck Medical University)