Marine Geophysics and Hydroacoustics

Caldera Lake Bolsena (Italy)


The Bolsena caldera formed between 0.6 and 0.2 Ma is an ideal site to study the tectonic and volcanic evolution of calderas. The main area is covered by an 150 m deep lake. A High resolution hydro-acoustic survey using a multichannel reflection seismic system and a sediment echo-sounder system were conducted in Sept. 2012.

As space was limited we used a rowing boat towed by a rubber boat to handle a 36 m long and 24 channel streamer to receive seismic reflections produced using a Mini GI-Gun (0.25 l). More


The subsurface structure of Lake Bolsena was imaged up to a sediment depth of ~ 190 m, which is estimated to have filled over a period of 333 kyrs. Massive pyroclastic flow deposits found in the deeper parts of the basin indicate an initial infill of volcanic deposits from two adjacent younger calderas, the Latera (W) and Montefiascone (SE) calderas.

Our data suggest that the caldera has a long history of active volcanism, because the lacustrine sediments show post-sedimentary influences of geothermal fluids. Our new geophysical data set is a valuable record with a potential to constrain the sedimentary and volcanic evolution of the Vulsini Volcanic District in areas that have not been assessed previously due to logistical challenges of conducting surveys in water-filled settings.

Seismic Beispiel

Seismic cross section at Lake Bolsena with interpreted drawing.

Innomar Beispiel

Innomar sediment echosounder image of Lake Bolsena.


Person to contact: Prof. Dr. Sebastian Krastel

Participants: Katja Lindhorst

scientific expedition: September 2012

project publications:

  • Lindhorst, K., Krastel, S., Wagner, B., Schuerer, A., 2017. Evidence for sub-lacustrine volcanic activity in Lake Bolsena (central Italy) revealed by high resolution seismic data sets. Journal of Volcanology and Geothermal Research.