The International Macroseismic Scale 2025 (IMS-25) developed by the IMS working group should be the basis for the evaluation of seismic intensity world-wide now and for next generations of seismologists and engineers. IMS-25 is a revision and extension of parts of the European Macroseismic Scale of 1998 (EMS-98), which was also published in the series of the Cahiers du Centre Européen de Géodynamique et de Séismologie du Conseil de l’Europe, but contains innovative elements and implements lessons learned from earthquakes and macroseismic observations since 1998.
The main considerations in developing the IMS are seen in the introduction of additional building types and in the elaboration of an extended Vulnerability Table, covering 26 types of structure, for each defining a most likely class and probable ranges among the six vulnerability classes (A to F). Tables with drawings for the classification of damage grades for additional building types were generated. The tables describe the five damage grades for adobe, masonry, reinforced concrete, traditional and common timber structures.
The assignment of vulnerability classes and damage grades is supported by an extended set of example illustrations. Focus is given to provide more insight and an as easy as possible entrance for users without engineering expertise in the evaluation of buildings with Earthquake-Resistant Design (ERD).
Following the Introductory Notes on background, principles and aims of the scale, the IMS-25 consists of Part I, i.e., the Core Scale (pages 17 - 28), including the description of the basic terms used in the scale, the short form (page 29) and is supplemented by Part II, the guidelines for using the scale and assigning intensity (pages 31 -85) and its dominating innovative part, the collection of 67 example illustrations (pages 87 – 153).
Fundamental principles in developing the IMS-25 were, first, not changing the internal consistency with the EMS-98. Thus, the IMS-25 maintains backward compatibility and the scale's simplicity such that it not only meets the needs of seismologists but also the needs of building inspectors and civil engineers.
The development of the IMS-25 was the subject of symposia or sessions at the World Conference on Earthquake Engineering (IAEE) 2024 in Milan, the General Assembly of the European Seismological Commission (ESC) 2024 in Corfu, Greece, and the European Conference on Earthquake Engineering (EECE) 2026 in Berlin. The presentations and papers provide essential background information about the contributions of the authors and other experts to IMS-25.
The International Macroseismic Scale 2025 IMS-25 by G. Grünthal, R.M.W. Musson, J. Schwarz, R. Spence, D.J. Wald, T. Wenk DOI: https://doi.org/10.25643/dbt.69483 is now available.
