The collision of the Indian and Eurasian plates caused a massive surface uplift and formed the Himalayas. Throughout the 2500-km long Himalaya mountain range, significant earthquake hazards have occurred either on the interface between the plates, above the interface at the Himalayan wedge, or below the interface within the subducting Indian plate (Bai et al., 2019; Bilham et al., 2019; Shi et al., 2020). Future destructive earthquakes will continue to be major sources of seismic hazard to millions of people in the region. It is thus important to examine the properties of large earthquakes that have occurred along the Himalayan orogenic belt. Here we revisit the source parameters of the 2005 Mw7.6 Kashmir earthquake and its aftershock sequence that have occurred at the western Himalaya syntaxis. The major tectonic feature for source area of the 2005 Kashmir earthquake is the rapid shift of the Himalayan orogenic belt from southeast to southwest direction. Introduction to the 2005 Kashmir earthquake On October 8, 2005 at 3:50 am GMT time (8:50 am local time), a Mw7.6 earthquake occurred in Kashmir, western Himalayan syntaxis (Fig. 1). This earthquake occurred at the densely-populated northern Pakistan close to the Kohistan Arc and Peshawar Basin, caused more than 87000 fatalities, a fivefold number of injuries and nearly four million people homeless (Powali et al., 2020). Since last century, more than 20 earthquakes of Mw ≥ 7.0 have occurred on the Himalayan orogenic belt (Bilham et al., 2019) (inset in the Fig. 1). This was the most catastrophic earthquake among them. According to the International Seismological Centre (ISC) catalog, there were more than 1000 aftershocks with magnitudes greater than 3.5 within two years after the mainshock. Though local seismic stations are rare, many of these earthquakes were well-recorded by regional and teleseismic stations. In addition, there were developments in seismic velocity models, data processing methodologies, such as the multiple event location algorithm. These advances have made it worthwhile to revisit the source parameters of the 2005 Kashmir earthquake sequence. Relocations of the 2005 Kashmir earthquake and its aftershocks We relocated the mainshock and aftershocks using a multiscale double-difference earthquake relocation method (multiDD) (Bai et al., 2015, 2019), which we developed from the hypoDD method (Waldhauser and Ellsworth, 2000). The hypoDD method assumes a flat Earth model and is appropriate for local-scale calculations. We developed the multiDD method to include arrival times of other phases recorded by local, regional and teleseismic networks by taken the sphericity of the Earth into account. It minimize residuals between observed and theoretical travel time differences for pairs of earthquakes observed at the same station to reduce errors made by velocity models in locating earthquakes. We used arrival time data from reviewed ISC catalog for the mainshock and 800 aftershocks of Mw ≥ 4.0 within two-year time period. A vast number of new phase readings have been made on permanent and temporary A Reappraisal of the 2005 Kashmir Earthquake in the Northwestern Himalaya Syntaxis BAI Ling 1, 2, * , SU Hui 2 and ZHOU Yuanze 2 1 Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China 2 University of Chinese Academy of Sciences, Beijing 10086, China Citation: Bai et al., 2021. A Reappraisal of the 2005 Kashmir Earthquake in the Northwestern Himalaya Syntaxis. Acta Geologica Sinica (English Edition), 95(supp. 1): 22–24. * Corresponding author. E-mail: bailing@itpcas.ac.cn © 2021 Geological Society of China http://www.geojournals.cn/dzxbcn/ch/index.aspx https://onlinelibrary.wiley.com/journal/17556724 Fig. 1. Tectonic map of the study area. The red star is the 2015 Kashmir mainshock and red dots are aftershocks relocated in this study. Beach balls are focal mechanisms of the mainshock obtained from this study and those of the aftershocks of Mw ≥ 4.8 taken from the global centroid moment tensor (gCMT) catalog. The gray patches are coseismic rupture area. Black lines are the major faults. Thick arrow is the direction of Indian plate movement with respect to the Eurasian plate (Ischuk et al., 2013). The inset in the upper-right corner show the study area (red rectangle) and historic earthquakes of Mw ≥ 7.0 occurred since 1900. Acta Geologica Sinica (English Edition), 2021, 95(supp.1): 22–24