Review of GPS and Quaternary fault slip rates in the Himalaya-Tibet orogen

Previous studies related to the active deformation within the India-Asia collision zone have relied on slip rate data from major faults to test kinematic models for the region. However, estimated geodetic and Quaternary slip rates demonstrate large variability for many of the major faults in the region (e.g., Altyn Tagh and Karakorum faults). As a result, several studies have challenged the assumption that geodetic slip rates are representative of Quaternary slip rates. In this review, slip rate data from the Quaternary fault database for Central Asia are used to determine the overall relationship between Quaternary and Global Positioning System (GPS) slip rates for 19 faults. A least squares and Pearson correlation analysis are applied to investigate this relationship. To evaluate the sensitivity of the slip rate relationship to the presence/absence of individual faults and different Quaternary dating methods, the slip rates were systematically re-sampled. To account for the range of published uncertainties for slip rates, the Monte Carlo method was applied. Regression through 57 Quaternary/GPS slip rate pairs yields an r² value of 0.71. Results from the re-sampling analysis show that the inclusion or exclusion of slip rate data from specific faults (e.g., the Ganzi fault, Karakorum fault, Himalayan Main Frontal thrust and Main Pamir thrust) have the highest influence on the strength of the correlation (changing the Pearson correlation coefficient by + 0.08, + 0.05, − 0.06, and + 0.06, respectively). Furthermore, there appears to be a systematic bias in the agreement between rates such that Quaternary rates tend to be higher than GPS rates. This bias is likely due to assumptions embedded in the geomorphic reconstructions of offset landforms used for estimating Quaternary slip rates in the dataset. Taken together, these results suggest that GPS slip rates are more likely to represent Quaternary slip rates when strict fault selection and geomorphic dating criteria are applied. Cases of inconsistencies in slip rates over different time scales may point to differences in the sensitivity of various fault slip measurement methods more often than secular rate changes.