Title: A simple use of OR techniques to complete seismic records without magnitude value

Authors: M.C.M. Rodrigues; C.S. Oliveira

Addresses: Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal ' CERIS/Instituto Superior Técnico, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal

Abstract: We are working on modelling the phenomenon of seismic occurrences in the Azores region, which requires, among other characteristics, the knowledge of the magnitude of past events. Approximately 18,000 seismic records are available, but more than 3,000 (±17%) have no information on magnitude. In this paper, we propose a methodology to generate the missing values of magnitude. This is based on an unusual but very simple application of OR, where pseudo-random values of magnitude are generated according to the statistical distribution of magnitude in records where information is complete. Special care is exercised on the upper tail of the distribution. The procedure does not determine the magnitude of an earthquake at a specific date, but the records become more complete in the sense that the generated values have a statistical distribution identical to the observed values. Statistical tests and the confirmation of the Gutenberg-Richter law validate the methodology.

Keywords: natural phenomena simulation; simulation to complete missing values; upper tail generation; OR application; magnitude estimation; seismic process of occurrences; earthquake hazards; Azores.

DOI: 10.1504/IJOR.2024.142374

International Journal of Operational Research, 2024 Vol.51 No.3, pp.349 - 366

Published online: 28 Oct 2024 *

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