Elektromagnetisk undersökning av den postglaciala Pärvieförkastningen
Tidsperiod: 2015-01-01 till 2016-12-31
Projektledare: Jochen Kamm
Budget: 2 100 000 SEK
Fennoscandian endglacial faults are by far the largest encountered worldwide and are thus of great international interest. They control almost all seismicity in northern Sweden. The Pärvie fault is the largest known endglacial fault (>150 km), formed at the end of the last glaciation in an earthquake of magnitude 7-8, possibly rupturing the complete crust. Recent discoveries indicate that end-glacial faults may occur much further south than previously believed, so that similar ruptures in the future may jeopardize nuclear waste storage safety. Fault reactivation may also pose a seismic hazard for e.g. the Lule river dams or the Kiruna mine. Despite of numerous geological and geophysical investigations, little is known about the faulting mechanism. Thus, the causative conditions can not be determined and neither the fault evolution nor future ruptures can be predicted. Missing key elements are the deep fault geometry and fluid circulation patterns, likely reflected in the electrical conductivity distribution of the subsurface. Therefore, we propose to complement the available data with an electromagnetic data set and to construct a detailed electrical conductivity model of the Pärvie fault system down to several kilometers. Recent seismological evidence indicates that the Pärvie fault may be a reactivated, yet unknown proterozoic original structure, associated to fractured rocks possibly hosting large amounts of fluid - a hypothesis which can be tested using electromagnetics.