Improved Seismic Monitoring with OBS Deployment in the Arctic: A Pilot Study from Offshore Western Svalbard

Sr No: 95

SYMPOSIUM : J6 Marine Geophysics

Improved Seismic Monitoring with OBS Deployment in the Arctic: A Pilot Study from Offshore Western Svalbard

Zeinab Jeddi, University of Bergen, Norway
Lars Ottemoller, University of Bergen, Norway
CORRESPONDING & PRESENTING AUTHOR:
Mathilde Sorensen, University of Bergen, Norway
Sara Rezaei, University of Bergen, Norway
Steven Gibbons, Norwegian Geotechnical Institute, Norway
Marte Stromme, University of Bergen, Norway
Peter Voss, Geological Survey of Denmark and Greenland, GEUS, Denmark
Trine Dahl-Jensen, Geological Survey of Denmark and Greenland, GEUS, Denmark

The mid-ocean ridge system is the main source of earthquakes within the Arctic region. The earthquakes
are recorded on the permanent land-based stations in the region, although smaller earthquakes remain
undetected. In this study, we make use of three Ocean Bottom Seismographs (OBSs) that were deployed
offshore western Svalbard, along the spreading ridges. The OBS arrival times were used to relocate the
regional seismicity, using a Bayesian approach, which resulted in a significant improvement with tighter
clustering around the spreading ridge. We also extended the regional magnitude scales for the northern
Atlantic region for OBSs, by computing site correction terms. Besides location and magnitude improvement,
the OBS network was able to detect hundreds of earthquakes, mostly with magnitude below Mw 3, including
a swarm activity at the Molloy Deep. Our offshore observations provide further evidence of a low-velocity
anomaly offshore Svalbard, at the northern tip of Knipovich ridge that was previously seen in full-waveform
inversion. We conclude that even a single permanent OBS near the ridge would make a significant difference
to earthquake catalogs and their interpretation.

KEYWORDS : OBS, seismicity, arctic