Pseudo 3-D P wave refraction seismic monitoring of permafrost in steep unstable bedrock

Michael Krautblatter, Daniel Draebing

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


Degrading permafrost in steep rock walls can cause hazardous rock creep and rock slope failure. Spatial and temporal patterns of permafrost degradation that operate at the scale of instability are complex and poorly understood. For the first time, we used P wave seismic refraction tomography (SRT) to monitor the degradation of permafrost in steep rock walls. A 2.5-D survey with five 80 m long parallel transects was installed across an unstable steep NE-SW facing crestline in the Matter Valley, Switzerland. P wave velocity was calibrated in the laboratory for water-saturated low-porosity paragneiss samples between 20°C and -5°C and increases significantly along and perpendicular to the cleavage by 0.55-0.66 km/s (10-13%) and 2.4-2.7 km/s (>100%), respectively, when freezing. Seismic refraction is, thus, technically feasible to detect permafrost in low-porosity rocks that constitute steep rock walls. Ray densities up to 100 and more delimit the boundary between unfrozen and frozen bedrock and facilitate accurate active layer positioning. SRT shows monthly (August and September 2006) and annual active layer dynamics (August 2006 and 2007) and reveals a contiguous permafrost body below the NE face with annual changes of active layer depth from 2 to 10 m. Large ice-filled fractures, lateral onfreezing of glacierets, and a persistent snow cornice cause previously unreported permafrost patterns close to the surface and along the crestline which correspond to active seasonal rock displacements up to several mm/a. SRT provides a geometrically highly resolved subsurface monitoring of active layer dynamics in steep permafrost rocks at the scale of instability. Key Points Seismic refraction tomography is applied first time to rock wall permafrost The applicability is demonstrated in the lab and the field at relevant depths High-potential tool to investigate destabilization processes in permafrost rocks

Original languageEnglish
Pages (from-to)287-299
Number of pages13
JournalJournal of Geophysical Research: Earth Surface
Issue number2
StatePublished - Feb 2014


  • climate change
  • cryospheric change
  • permafrost degradation
  • rock permafrost
  • seismic refraction tomography
  • slope instability


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