USGS:Science for a changing world

USGS Workshop: SEISMIC AND TSUNAMI HAZARD IN PUERTO RICO AND THE VIRGIN ISLANDS
Colegio de Ingenieros y Agrimensores, San Juan, March 23-24, 1999

Workshop Home Page
Executive Summary
State of Knowledge
Working Group Reports:
 Marine geology/ geophysics
 Paleoseismology
 Earthquake seismology
 Engineering
 Tsunamis
 Societal concerns
Workshop Goals
Participants
Agenda
Acknowledgements

Earthquake Seismology and Engineering Joint Working Group Report

Engineering

E.V. Leyendecker (USGS-EHZ), J.M. Cruzado (U. Puerto Rico)

Members:

Mehmet Celebi (USGS-EHZ)


ENGINEERING

DESIGN ISSUES

  • Spectral acceleration values
  • Time histories
  • Directivity effects
  • Duration of strong ground motion

LIQUEFACTION MAPS

Liquefaction susceptibility maps should be prepared for urban areas. This is an important aspect of geotechnical investigations.

SITE RESPONSE

  • Update and improve types of site conditions in Puerto Rico. This is a first step in determining site amplification factors for use in determining site response.

  • Site effect observations and near-surface geophysical measurements will be needed, if local (urban-area) hazard maps, including site response, are ever anticipated.

INSTRUMENTATION

An expanded strong motion program is needed. This includes both free field instrumentation and building instrumentation. The priority is placed on free field instrumentation. Site locations should be carefully selected and the type of site classified by soil profile and shear wave velocity. Sites should include different types of material in order to evaluate site response.

Weak ground motion instrumentation can be used to obtain site response instrumentation. This type of instrument can be deployed on different types of sites to obtain site amplification in short periods of time. While it can be argued that this type of data might not be suitable for strong ground motion, it can be quite useful.

STRUCTURAL TYPES

Fragility curves should be developed for Puerto Rico construction types and details.

LABORATORY TESTING

Laboratory testing should be done on selected types of mass-produced construction.

CODE ENFORCEMENT

Code enforcement is limited due, in part, to a limited number of inspectors. Inspection of projects to ensure that what was designed is actually built is an important component of earthquake design and improvement is encouraged.

TSUNAMI DESIGN

Tsunami design should be considered in construction projects. This can be done through different means such as relocation or barriers, such as sea walls or wave energy dissipation devices. Maps of wave height and velocity would also be useful.

OUTREACH

  • A campaign to make the public more aware of the consequences of poor earthquake parameters.

  • Map data should be presented in different ways that would make it easier for the public to understand. An example would be a map portraying the probability of exceeding a code level design in the next 50 years.


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