A Mahalanobis-Distance-Based Copula Model Averaging Approach for Dependence Modelling with an Application to the Tehran Province Earthquake Catalogue

Document Type : original

Authors

Department of Statistics, Faculty of Mathematical Sciences, Alzahra University

Abstract
Copula models provide a flexible framework for modelling complex dependence structures between continuous variables. However, several competing copula families may provide similarly satisfactory fits, making inference based on a single selected model potentially unstable. To address this issue, a Mahalanobis-distance-based copula model-averaging approach is adopted to account for model uncertainty and obtain more stable estimates of conditional exceedance probabilities. Its performance is evaluated through simulation studies across a range of Kendall's $\tau$ values and illustrated using an earthquake catalogue from Tehran Province, Iran, to examine dependence between earthquake magnitude and inter-event time. The simulation results demonstrate stable estimation across different dependence structures. In the real-data application, appropriate marginal models are fitted before applying the copula framework, and the estimated conditional exceedance probabilities vary only slightly across elapsed-time thresholds. These findings suggest that elapsed time alone provides limited predictive information about the magnitude of subsequent earthquakes and highlight the value of incorporating model uncertainty into copula-based dependence modelling.

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Articles in Press, Accepted Manuscript
Available Online from 02 October 2026