Seismic survey on an open pingo system in Adventdalen Valley, Spitsbergen, Svalbard
2018
We present the results of a seismic survey on an open-system pingo, the Innerhytta pingo, located
in the Adventdalen Valley, Spitsbergen Island of the Svalbard Archipelago, Norway. To evaluate the
temporal evolution of permafrost, we need detailed knowledge of its heterogeneities, of which pingos
are the most visible markers. The seismic velocity contrasts and inversions peculiar to these
features can be a problem for a successful seismic survey. The present paper focusses on the limits
and benefits of various seismic methods for imaging the subsurface structure of the pingo, with the
aim of defining the best practice for shallow seismic exploration. We performed several tests, using
classical reflection/refraction arrays, seismic tomography, and surface wave analysis. We tested different
kinds of seismic sources and receivers. The combined use of several sources and receivers
sets and patterns, and the use of surface wave analysis and body wave tomography allowed constructing
a three-dimensional model of the velocities. For this particular pingo, beneath an approximately
15-m thick high-velocity layer, low velocities are found to be present at an anomalously
shallow depth. This low-velocity layer is interpreted to host the ground water circulation that controls
the pingo’s structural evolution. Such observations suggest feeding water flow from depth
rather than from the near surface, as commonly supposed for open-system pingos.
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