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Abstract. Glacier melt is an essential source of freshwater for the arid regions surrounding the Tian Shan. However, the knowledge about glacier volume and mass changes over the last decades is limited. In the present study, glacier area, glacier dynamics and mass changes are investigated for the period ~1975–2007 for Southern Inylchek Glacier (SIG) and Northern Inylchek Glacier (NIG), the largest glacier system in Central Tian Shan separated by the regularly draining Lake Merzbacher. The area of NIG increased by 2.0 ± 0.1 km2 (~1.3%) in the period ~1975–2007. In contrast, SIG has shrunk continuously in all investigated periods since ~1975. Velocities of SIG in the central part of the ablation region reached ~100–120 m a−1 in 2002/2003, which was slightly higher than the average velocity in 2010/2011. The central part of SIG flows mainly towards Lake Merzbacher rather than towards its terminus. The measured velocities at the distal part of the terminus downstream of Lake Merzbacher were below the uncertainty, indicating very low flow with even stagnant parts. Geodetic glacier mass balances have been calculated using multi-temporal digital elevation models from KH-9 Hexagon (representing the year 1975), SRTM3 (1999), ALOS PRISM (2006) and SPOT-5 high-resolution geometrical (HRG) data (2007). In general, a continuous mass loss for both SIG and NIG could be observed between ~1975 and 2007. SIG lost mass at a rate of 0.43 ± 0.10 m w.e. a−1 and NIG at a rate of 0.25 ± 0.10 m w.e. a−1 within the period ~1975–1999. For the period 1999–2007, the highest mass loss of 0.57 ± 0.46 m w.e. a−1 was found for NIG, whilst SIG showed a potential moderate mass loss of 0.28 ± 0.46 m w.e. a−1. Both glaciers showed a small retreat during this period. Between ~1975 and 1999, we identified a thickening at the front of NIG with a maximum surface elevation increase of about 150 m as a consequence of a surge event. In contrast significant thinning (>0.5 m a−1) and comparatively high velocities close to the dam of Lake Merzbacher were observed for SIG, indicating that Lake Merzbacher enhances glacier mass loss.

SUMMARY Significant land subsidence was recently recognized in northeast Iran, near the city of Mashhad. Precise levelling surveys performed in 1995, 2002 and 2005, indicate as much as 90 cm of subsidence during the 1995–2005 period. Continuous GPS monitoring approximately 8 km northwest of Mashhad City shows more than 20 cm yr−1 subsidence between 2005 and 2006. We use Interferometric Synthetic Aperture Radar (InSAR) measurements to detect the temporal and spatial pattern of this surface deformation. 13 interferograms from 10 C‐band SAR images acquired by the Enivsat satellite from 2003 to 2005 are analysed and stacked. Our InSAR mapping suggests that subsidence occurs within a northwest–southeast elongated elliptic‐shaped bowl along the axis of the Mashhad valley, with a peak amplitude of ∼28–30 cm yr−1 for the 2003–2005 time period. The InSAR data indicate that approximately 70 km2 in the valley floor, including the northwestern part of Mashhad City, subsided at a rate exceeding 15 cm yr−1 between 2003 and 2005, and that the subsidence area is structurally controlled by the trends of Quaternary faults cutting the valley floor. Analysis of piezometric records suggests that subsidence likely results from extensive overdrafting of the aquifer system in the valley that has caused as much as 65 m of water table decline since 1960s.

S U M M A R YDifferential radar interferometry provided high-quality near-field deformation data for the 2003 Bam earthquake and therefore strong constraints on its source parameters. The ruptured fault segments could be clearly detected by using a Sobel Edge Filter on the phase-unwrapped deformation field. The estimated total rupture length is about 24 km. More than 80 per cent of the seismic moment was released from its southern segment of about 13 km, where the slip reached a maximum of up to 270 cm resulting in a stress drop of at least 6 MPa. In addition, optical remote sensing data show that the Bam fault is not a single fault but consists of a 4-5 km wide fault system with the known main branch running between the city of Bam and Baravat. The fault ruptured by the Bam earthquake appears to continue the NW branch of this fault system from Bam city southwards. Based on these results, we suggest that the Bam earthquake ruptured a hidden or new fault and that in this process an unusually strong asperity was involved.