Abstract
During the past century, seismicity along the Tjornes Fracture Zone (TFZ), North Iceland, resulted in infrastructure damage and landscape changes. However, many faults responsible for these events (up to Mw 7) including those that form the Dalvík Lineament (DL), are poorly understood. Remote sensing mapping coupled with fit-for-purpose drone-derived structure from motion data and field mapping were used to identify faults, dikes, and Quaternary elements such as large landslides along the DL. Importantly, in contrast to other faults or seismic lineaments in the TFZ, there is no through-going mappable DL fault scarp. Instead, there is a coincidence between the mapping of dikes and seismicity as generally north-south trends. Landslide distribution and frequency are correlated with seismicity along portions of the DL and dikes mapped in the field. These landslides are most spatially concentrated in zones with higher microseismicity. Many of the landslides have headscarps coincident with dikes that cut the regional lava pile. While prior studies suggest that landslide events were triggered by glacial debuttressing and permafrost melt, our data suggest seismic and structural controls (i.e. dikes) on major landslide frequency and distribution in the Tröllaskagi region. Through the development of a 3D model of one local along the northwestern area of the DL, it is clear that low-temperature geothermal fields in the Tröllaskagi Peninsula align with these dikes. This shows the importance of geological structures in controlling subsurface fluid flow, in particular when regional bedding of the stratified sequences intersects dikes down dip which can aid geothermal exploration.