Felix Halpaap

Unearthing a link between old and new plate boundaries and present-day seismotectonics of Svalbard: First insights from the new high-res 700k earthquake catalog of the European plate’s far North

Abstract:
Oceanic ridges and transform faults comprise nearly 45% of the Earth’s plate boundaries. Even though they have lower seismic moment release rates than convergent plate boundaries, these intricately segmented oceanic plate boundaries host a large part of Earth’s seismicity. Analyzing how their segmentation is expressed through their seismic behavior has not been commonly possible due to limited observations compared to plate boundaries on land. This knowledge gap has also hampered efforts to understand the causes of seismicity in regions adjacent to the plate boundaries, such as the Svalbard archipelago. A challenge for these remote areas is that there is often no overlap between event catalogs produced routinely from regional networks (typically with M>3.5) or from short local deployments (M<3). To close this gap, we apply a sensitive earthquake detection pipeline to complement a regional catalog over 25 years through HPC-supported template matching. We focus on the 3000 km of oceanic plate boundaries and adjacent areas in the European Arctic (68° – 87°N, 20°W – 40°E). From an initial dataset of 35k earthquakes, we obtain a new catalog of 700k events, including 150k events with high-resolution relative locations and ~80k glacial events. In this talk, I present this new data product with a focus on four areas where our analysis has unearthed completely new faults and seismicity patterns: (i) the amagmatically rifting Lena trough, (ii) the ultraslow-spreading Mohn and Knipovich ridges, (iii) the transform fault-bound Molloy deep, (iv) and the transtensional fault arrays of Nordaustlandet and Spitsbergen. We correlate the latter fault patterns with former plate-bounding thrust faults of the Timanian orogeny and compare the seismicity patterns with those found in transtensional settings along the San Andreas fault. Since this catalog contains far more new seismicity features than one can analyze alone, we invite everyone to explore this unique data product and to discuss new findings in the light of geodynamics and plate tectonics, field and structural geology, ridge tectonics and volcanism, and other phenomena such as methane seeps and glacial activity on Svalbard.