Projects / Programmes
Application of sonar in research of active tectonics and paleoseismology in low-strain environments
| Code |
Science |
Field |
Subfield |
| 1.06.06 |
Natural sciences and mathematics |
Geology |
Regional geology |
| Code |
Science |
Field |
| P005 |
Natural sciences and mathematics |
Geology, physical geography |
| Code |
Science |
Field |
| 1.05 |
Natural Sciences |
Earth and related Environmental sciences |
paleoseismology, active tectonics, geophysical investigations, sonar
Researchers (13)
Organisations (2)
Abstract
We propose the application of high-resolution acoustic sonar surveying of microtopography and sub-bottom structure of sub-aqueous sediments as a potentially powerful tool in identifying indicators of active tectonic deformation and paleoseismicity. The normally good preservation of sediments in sub-aqueous environments coupled with sub-decimeter resolution of the method make our approach particularly suitable to low-strain tectonic environments, where conventional indicators of active tectonics may be absent or difficult to identify. Additionally, surveying on water bodies is in most cases simpler, quicker and cheaper than conventional land-based geophysical surveying and paleoseismological trenching. Our principal objective is to develop and calibrate the methodology, and to test it on selected well-investigated marine, lacustrine and riverine sites in Slovenia where active tectonic deformation was already confirmed by other methods. Results of the project may therefore also improve the existing regional seismotectonic models and the reliability of seismic hazard assessment.
Significance for science
In investigations of active tectonics and paleoseismology, the sub-bottom and multibeam sonar surveying of the bathymetry and subsurface structure represents a complementary method and sometimes a cheap alternative to reflection seismic surveying. Sonar surveying facilitates data acquisition in higher resolution which can be carried out in practically all types of waterbodies, regardless of water depth and navigability. The high-resolution of acquired data makes this method particularly suitable for detecting small offsets in slowly deforming regions. Marine, lacustrine and fluvial sediments represent one of the most reliable and accessible archives of recent tectonic activity in environments of low-intensity deformation. Therefore our proposed method presents an important tool in paleoseismic research and subsequent hazard assessment. In the project we developed a workflow which is fully 3D based and which introduces techniques common in reflection seismics to sonar data acquisition, processing and interpretation. The workflow is based on using relatively low-cost surveying equipment, coupled with open-source and free software for processing and interpretation of the data, which makes it accessible to a wide range of users from the academic and private sectors. In the project we investigated Quaternary tectonic deformation in the Gulf of Trieste, which is a part of the wider Adria-Eurasia collision zone. The 3D structure, recent activity and the rates and localization of deformation in this zone represent one of the outstanding problems in understanding of the recent dynamics of the Alpine orogenic system. In our reflection seismic profiling campaign SLOMARTEC 2013 we obtained key data for defining the geometry, kinematics and temporal evolution of tectonic structures in the Slovenian coastal area. Our study area furthermore represents a unique setting where offshore structures can be directly correlated with the structures that were mapped and investigated in detail onshore in the Slovenian coastal region. Our results prove that in the Gulf of Trieste there was no major Quaternary tectonic deformation, which suggests that the active part of the collision front is located further to the north. We identified several offshore sub-vertical Quaternary-active faults. Our analysis of geomorphic indicators of tectonic activity suggest that an active seismogenic fault is located in the Gulf, probably near the Debeli rtič Cape. Our application of sonar-derived bathymetric and paleotopographic models as geomorphic indicators of tectonic activity presents a novel approach in studying of active tectonic processes. Despite the low value of estimated tectonic displacement rates, our results warrant a new evaluation of the seismic hazard in the Gulf of Trieste and its surroundings. We used high-resolution sonar profiling to study the stratigraphic architecture and geomorphic features of the youngest part of the sedimentary record of the Gulf of Trieste, which comprises transgressional transition from Pleistocene continental to Holocene marine sedimentation. Our project was the first to use a 3D approach to study the sediment architecture and sediment deposition mechanisms in the Gulf of Trieste. We also compiled data from Slovenian and Italian project partners to create the first transboundary map of the Holocene marine sediment thickness in the Gulf. This map will facilitate future integrative studies of sedimentary, tectonic, erosional and climatic processes affecting Holocene marine sedimentation in this area.
Significance for the country
The methodology of sonar surveying developed in this project has considerable potential for commercial applications. It is suitable for site assessment when designing major infrastructural objects which are critically vulnerable to seismic hazard and are directly or indirectly associated with water bodies, such as hydroelectric and nuclear power plants, but also in site investigations and hazard assessment of existing objects such as hydroelectric dams. Project results are directly relevant for the co-funding company Harpha Sea d.o.o., as the developed methods and workflows will considerably increase its portfolio of expertise and services. Of key importance is the newly established interdisciplinary connection with geology, which will in future projects and applications allow Harpha Sea staff to independently interpret the acquired geophysical data. It is expected that the existing clients such as hydroelectric power companies and port authorities will be highly interested in the expanded know-how and expertise, whereas the offer of new services that integrate surveying and data acquisition with interpretation will likely allow the expansion of operation in foreign markets. The project has provided important new data about Quaternary tectonic activity in the coastal area of Slovenia, which was so far not investigated in this respect. The new data represent entry parameters for seismic hazard assessment, which serves for development of State-prescribed guidelines for designing and building of infrastructural, industrial and private facilities. The multichannel seismic reflection data from the Slovenian offshore, acquired in the project in the SLOMARTEC 2013 campaign in collaboration with the partner OGS (Istituto Nazionale di Oceanografia e Geofisica Sperimentale), represent a major new asset for the Republic of Slovenia. This industrial-grade geophysical survey is the first investigation of subsurface geological structure in the territorial waters of Slovenia, and is fundamental for evaluation and development of natural resources and alternative energy sources. Survey data was delivered to three government Ministries. In the frame of the project we developed a long-term collaboration with the OGS institute, which involved training of researchers, exchange of research equipment, and knowledge transfer. At the Faculty of Natural Sciences and Engineering of the University of Ljubljana we established the infrastructure for processing and interpretation of acoustic geophysical surveys, comprising hardware, software and data archiving facilities. Training of a new PhD specialized in geophysical surveying of seabottom sediments was started in the project. New knowledge and data products acquired in the project were introduced in the teaching process at the faculty at all three study levels.
Most important scientific results
Annual report
2013,
final report
Most important socioeconomically and culturally relevant results
Annual report
2013,
2014,
2015,
final report
