SEISMIC RISK – Mitigation of induced seismic risk in urban environments

In the SEISMIC RISK -Mitigation of induced seismic risk in urban environments -project, the research consortium consisting of University of Helsinki, VTT Technical Research Centre of Finland and Geological Survey of Finland is studying how to mitigate induced seismic risk associated with deep geothermal power stations in Finland. Small-magnitude earthquakes pose a risk to critical sensitive infrastructure such as hospitals, data centres and underground construction. Risk can be mitigated with transparent permitting, seismic monitoring and regional planning. The project will publish a set of seismic hazard maps of Finland and especially of the Helsinki Capital Region and assess the potential impact of seismic waves on different parts of the capital area via3D models: shear wave tomography, conceptual soil and bedrock model. The project will study the different roles the national, regional and municipal governance in the “wicked” permitting processes. It will assess what information on induced seismicity and associated risks and at what level of detail the authorities need it.Non peer reviewe

From a collage of microplates to stable continental crust - an example from Precambrian Europe

Volume: 15 Host publication title: EGU General Assembly 2013 Proceeding volume: 15Svecofennian orogen (2.0-1.7 Ga) comprises the oldest undispersed orogenic belt on Baltica and Eurasian plate. Svecofennian orogenic belt evolved from a series of short-lived terrane accretions around Baltica’s Archean nucleus during the formation of the Precambrian Nuna supercontinent. Geological and geophysical datasets indicate W-SW growth of Baltica with NE-ward dipping subduction zones. The data suggest a long-lived retreating subduction system in the southwestern parts whereas in the northern and central parts the northeasterly transport of continental fragments or microplates towards the continental nucleus is also documented. The geotectonic environment resembles that of the early stages of the Alpine-Himalayan or Indonesian orogenic system, in which dispersed continental fragments, arcs and microplates have been attached to the Eurasian plate margin. Thus the Svecofennian orogeny can be viewed as proxy for the initial stages of an internal orogenic system. Svecofennian orogeny is a Paleoproterozoic analogue of an evolved orogenic system where terrane accretion is followed by lateral spreading or collapse induced by change in the plate architecture. The exposed parts are composed of granitoid intrusions as well as highly deformed supracrustal units. Supracrustal rocks have been metamorphosed in LP-HT conditions in either paleo-lower-upper crust or paleo-upper-middle crust. Large scale seismic reflection profiles (BABEL and FIRE) across Baltica image the crust as a collage of terranes suggesting that the bedrock has been formed and thickened in sequential accretions. The profiles also image three fold layering of the thickened crust (>55 km) to transect old terrane boundaries, suggesting that the over-thickened bedrock structures have been rearranged in post-collisional spreading and/or collapse processes. The middle crust displays typical large scale flow structures: herringbone and anticlinal ramps, rooted onto large scale listric surfaces also suggestive of spreading. Close to the original ocean-continent plate boundary, in the core of the Svecofennian orogen, the thickened accretionary crust carries pervasive stretching lineations at surface and seismic vp-velocity anisotropy in the crust. The direction of spreading and crustal flow seems to be diverted by shapes of the pre-existing boundaries. It is concluded that lateral spreading and midcrustal flow not only rearrange the bedrock architecture but also stabilize the young accreted continental crust in emerging internal orogenic systems. Pre-existing microplate/ terrane boundaries will affect the final architecture of the orogenic belt.Non peer reviewe

BABEL7: Crustal‐Scale Extension Associated with the Formation of the Baltic Sea Paleorift, Fennoscandian Shield

Peer reviewe

BABEL4: Crustal Structures of the Precambrian Svecofennian Accretionary Orogen in the Fennoscandian Shield

Peer reviewe

BABEL3&3a : Crustal-Scale Structures of the Precambrian Svecofennian Accretionary Orogen in the Fennoscandian Shield

obs typo in the title: The title will be changed to FIRE3&3A: Crustal-Scale Structures of the Precambrian Svecofennian Accretionary Orogen in the Fennoscandian Shield. in the second printed version.Peer reviewe

Development of an in-situ magmatic dome (Svecofennian accretionnary orogen, Finland)

Volume: 16This study focuses on the formation of the 100 km wide Vaasa magmatic dome (Svecofennian orogen, Finland). It is cored by diatexite migmatites and granitoids and gradually mantled by metatexite migmatites and mica schist. Geochemical data have demonstrated that the later are the sources of the melted core. This is an agreement with new petrological modeling showing an increase of temperature from 500C to up to 800C at constant pressure (5-6 kbar) from the border to the core of the dome (peak). Field work studies highlights the initial formation of a layered middle crust with a strong lateral increases of in-situ melt content towards the core of the dome. It is followed by a regional shortening and exhumation along sub-vertical shear zone during a persistent high-temperature thermal anomaly. This may be the result of distributed thickening competing with regional shortening and perturbed by lateral increase of in-situ melting within middle crust towards the dome core. Sub-crustal continuous underplating of magma in this accretionnary orogen might be responsible for the origin of the thermal anomaly and formation of this 1.87 Ga in-situ magmatic dome.Non peer reviewe

OpenFIRE – A Web GIS Service for Distributing the Finnish Reflection Experiment Datasets

Non peer reviewe

How to deliver information on induced seismicity to the authorities and general public?

Non peer reviewe

Geoterminen energia ja politiikkaongelmien hallitsemisen tiedollinen haaste

Peer reviewe