In location-based social Q&A services, people ask a question with a high expectation that local residents who have local knowledge will answer the question. However, little is known about the locality of user activities in location-based social Q&A services. This study aims to deepen our understanding of location-based knowledge sharing by investigating the following: general behavioral characteristics of users, the topical and typological patterns related to geographic characteristics, geographic locality of user activities, and motivations of local knowledge sharing. To this end, we analyzed a 12-month period Q&A dataset from Naver KiN "Here," a location-based social Q&A mobile app, in addition to a supplementary survey dataset obtained from 285 mobile users. Our results reveal several unique characteristics of location-based social Q&A. When compared with conventional social Q&A sites, users ask and answer different topical/typological questions. In addition, those who answer have a strong spatial locality wherein they primarily have local knowledge in a few regions, in areas such as their home and work. We also find unique motivators such as ownership of local knowledge and a sense of local community. The findings reported in the article have significant implications for the design of Q&A systems, especially location-based social Q&A systems.