Complete historical chronology of complex landslide movements? Improving the tree-ring based results using multidisciplinary approaches

• A unique landslide chronology was compiled from three independent sources. • Dendrogeomorphology , archival data and monitoring data were combined. • The maximum complete chronology has a length of 184 years. • The chronological data was used for the analysis of potential triggers. Chronologies of landslide movements are a key dataset for determining their frequency, assessing landslide hazard and potential triggers. However, data on historical landslide activity are incomplete or completely lacking, so the accurate alternative to obtain them is to use dendrogeomorphic methods. Even this approach has its limitations, and the resulting chronologies of movements are generally considered to be minimal and including uncertainties. Thus, in the context of this study, an attempt was made to complement and cross-validate tree-ring based chronologies of landslide movements with two other independent sources of chronological information. The main part of the chronology was constructed from 177 disturbed European beech ( Fagus sylvatica L.) individuals. Archival records helped to complement the data from an earlier period than the age of the trees and to verify the chronology, and conversely, the more recent period (approximately the last two decades) was accurately supplemented with monitoring data. The resulting chronology thus reaches 184 years (1839–2022) and was used for the analysis of potential triggers, which are represented by several days of extreme rainfall. This study also discusses the limitations of the different approaches, which are mainly related to the different ability to add spatial information to the chronology and the different abilities to determine the magnitude of the landslide movement. This study clearly indicated that historical forest management data can be used (necessary in the case of high intensity of management) in dendrogeomorphic reconstruction. These data will allow a more effective interpretation of the detected tree growth disturbances as well as the chronological evolution of sample size, which is crucial for the calculation of an event-response index expressing the intensity of the landslide event.