Geofizički seminar: Lars Ottemöller

SAŽETAK:

Earthquake swarms are observed in various tectonic environments such as plate boundaries and volcanoes and are often associated with migration of fluids. However, they also occur in intraplate areas that are located away from plate boundaries and tectonically less active. This presentation will focus on earthquake swarm activity in the Nordland region of Norway, and compare to New Madrid (USA) and Palghar (India). The main physical cause for earthquakes is tectonic stress, but fluids and hydrological load are considered to play a triggering role. In Norland, we find that load change due to snow is observed in GNSS data and that maximum snow load correlates with triggering of earthquake swarms. Stress transfer between earthquakes and pore pressure diffusion are considered to maintain the swarm activity once it starts. In Nordland, the nature of swarm activity appears to change over relatively short distance, and can be linked either to complex fracture zones or localized fault intersections.