Seismic Hazard Mapping for Guatemala

This is the first report of the study on Seismic Risk for Guatemala. This phase of the study includes the collection and description of geological and seismological environment and the use of that information in developing iso-acceleration maps of Guatemala. This phase of the study gives results on future probable seismic hazard for Guatemala which can be utilized by engineers in formulating the seismic codes, by planners in future developments and by the insurance companies in evaluating the seismic risks and rates. Various state-of-the-art models are used to develop this hazard information.

Phase II of the project will involve the following topics:
- A thorough study of the 1973 UBC, the 1976 UBC and the ATC-3 work currently being completed. The above codes will be evaluated with the seismicity of Guatemala in mind. Such an evaluation will permit the engineers and planners in Guatemala to appreciate and understand 'the current code levels and their relationships with future seismic loading demands.
- A detailed discussion on the purpose and effects of earthquake codes will be presented. This will include the history of earthquake loading criteria, the relation of design loads and quality of structures, the objectives and qualities of workable seismic codes and the role of design detailing and design forces in providing a safe economic construction.
- Introduction to the Proposed Seismic Design Provisions. This will take into account the current codes, their advantages, their shortcomings and the available solutions to eliminate or reduce the shortcomings. This part of the study will explain in detail the concept of acceptable risk and the associated loading levels from the hazard maps of Guatemala. The study will also develop the shape and levels of various design spectra. These spectra will include the site characteristics information.
- A detailed description of the type of structural systems, their effects on the design level and a step-by-step design procedure will be developed.
- Based on the spectral approach of seismic design, a simplified equivalent static load method, similar to the 1976 UBC method of design, will be developed.

It should be emphasized here that a workable code should have the following four ingredients:
1) Simplicity.
2) Rationality.
3) Freedom to use responsible ingenuity for special structures.
4) Reward and encouragement for using dynamic analysis when merited by the complexity of a given structure.

In developing the methodology in part II of this study, the above four ingredients will be kept in mind.

Finally, a detailed comparison with the proposed methodology and the 1976 UBC will be made. This will be done with the seismic environment of Guatemala in mind. It is estimated at this time that the results of phase II study will be submitted before the end of September 1977.