This is an older version of the hazard software. It was used for earlier versions (pre-1996) of the hazard maps. It was not used for the 1996 or newer hazard maps.

Background Information

Seisrisk III is the last published version of a series of programs used to produce probabilistic earthquake ground motion hazard maps for the United States from 1972 to 1992. Though it has been superseded in the US Geological Survey by a more flexible program allowing for sources based on smoothing of historical seismicity, Seisrisk III is still being used as a teaching tool in academia and for hazard mapping in other countries. In the past decade, Seisrisk III has been used for hazard mapping in Italy, Turkey, Iran, in the Mediterranean countries as a whole, and in the West Indies, for example.

Because of this continuing interest, we are continuing to host the source code and references to publications on the structure and the use of Seisrisk III, including auxiliary programs for the construction of input. However, except for answering a few helpful questions, we are no longer providing support or advice for users. We are also hosting a set of program modifications to Seisrisk III written by a colleague in the Bureau of Reclamation. We are aware that other modifications exist, for instance, one version adapted to use intensity and its uncertainties instead of parametric ground motions, and another adapted to use non-circular isoseismals for point sources. These can be found by diligent search of the internet.

Known Issues

We are aware of some known issues with the software however we have no plans to fix any of the following or other issues: