Near-surface seismic refraction tomography and electrical resistivity imaging were used to study the collapse and subsidence of two asphalt roads on the campus of South Valley University in southern Egypt. The roads surround a garden where irrigation water was suspected to be the cause of the damage to the asphalt roads. Two seismic refraction tomography (SRT) lines were measured on the asphalt roads, and a single SRT line and an electric resistivity tomography (ERT) line were measured within the garden. The tomographic inversion of the SRT lines on the road shows several low velocity anomalies indicating areas of weakness beneath the asphalt. The SRT and ERT lines in the garden show a thin surface soil of fine sand and clay overlying a low electric resistivity and low seismic velocity clay layer. Examination of the results suggests that the damage to the asphalt roads could be caused by the presence of loose silt and clay soil that was used as a sub-base for the asphalt. This soil had not been compacted and engineered for use as a strong base layer. Instead, the asphalt was laid directly on top of it, which later led to the

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 80m 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 degrees C and -5 degrees C and increases significantly along and perpendicular to the cleavage by 0.55-0.66km/s (10-13%) and 2.4-2.7km/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.