A Novel Method for Completeness Period in Seismic Hazard Assessment: Overcoming Drawbacks of Stepp’s Method and Validation Using Regional Catalogue

A crucial aspect of seismic hazard assessment involves evaluating the completeness of the available seismic data. Numerous researchers have introduced different methods for analysing the completeness of event records, with Stepp’s method being one of the most widely utilized approaches. This method relies on calculating the standard deviation of the mean annual occurrence rate of events, which is then plotted on a log-log scale. The completeness period for the seismic event record is determined by identifying the stable slope of the standard deviation in relation to the − 1/2 slope line. Standard deviation is expected to decrease with time, and it will also reduce if events are missing. Hence, it is not very sensitive if events are missing. Again, the position of − 1/2 slope line is decided by eye estimation only, which is highly subjective and not very accurate in finding the completeness period. The primary aim of this study is to evaluate the sensitivity of Stepp’s method and to introduce an alternative approach for estimating the completeness period. This new method is utilizing a moving average approach for the annual frequency of earthquake occurrences, which is anticipated to remain statistically stable over time. Hence, any slight change in the rate can be easily detected if events are missing. In this study, sensitivity of the moving average method is compared with Stepp’s method using a hypothetical catalogue and found to be more sensitive for the missing events. Results from completeness analysis of a regional catalogue by both the methods are also compared, and it is concluded that the moving average method is more sensitive and accurate as compared to the Stepp’s method.