International Macroseismic Scale

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Macroseismic Intensity is a classification of the severity of ground shaking on the basis of observation of observed effects in a limited area. Macroseismic Intensity has a very important role in seismology as for many events only observations are available, including events distant from ground measurement instruments, and those which took place in the historic past. Of the several macroseismic intensity scales in use, EMS-98 is the one with the clearest distinction between effects on different types of building. It was originally designed for use in Europe, but has been widely used internationally.

Following an initiative by the GEM Foundation in 2010, a Working Group was set up to review EMS-98 with a view (amongst other aims) to extending and clarifying its description of building type, so that it can be used internationally, and to create a new International Macroseismic Scale.

CAR were commissioned by the GEM Foundation to prepare a draft of Part III of IMS, the Building Guide, (covering Building Typology, Vulnerability and Damage). Specific extensions beyond what is included in EMS-98 included:

  • More precise definitions of the building typologies and sub-types which are needed for vulnerability class definition.

  • Information on a range of regional variations of the principal building typologies, and likely vulnerability classes for each variant.

  • Refinement of the way in which the level of earthquake resistant design is to be identified, and used to define the vulnerability class, extending earthquake-resistant design modifiers to masonry, steel and timber structures.

  • Roughly quantified vulnerability modifiers to enable effects of e.g. age condition and configuration to be approximately accounted for in assigning a vulnerability class to a building or group of buildings.

  • Additional photographic examples of buildings with different damage states.

  • A new set of diagrammatic representations of damage at each of the 5 damage states, including drawings for steel and timber buildings, as well as new drawings for reinforced concrete and masonry buildings.

The draft submitted to the Working Group in October 2014 can be found at:

 

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PDF icon RISK Intl Microseismic scale.pdf1.04 MB
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