Project Title/ID Number Next Generation Attenuation (NGA) Models, WUS Shallow Crustal Earthquake—Lifelines 1L01
Start/End Dates 10/1/02—9/30/03
Project Leader Maurice Power (Geomatrix/Industrial Collaborator)
Team Members Robert Youngs (Industrial Collaborator), I.M. Idriss (UCD/Faculty), Kenneth Cambell (ABS/Industrial Collaborator), Yousef Bozorgnia (Industrial Collaborator)
Project goals and objectives

The overall goal of project 1L Series is to develop Next-Generation Ground Motion Attenuation (NGA) Models for shallow crustal earthquakes in the western United States. Project Task No. 1L01 covers two components of the NGA project:

  1. project coordination – project coordinator Maurice Power; and
  2. participation of three of the teams developing NGA models – Robert Youngs and Brian Chiou (Task 1L01 provides support for Robert Youngs; Brian Chiou is directly supported by Caltrans); Kenneth Campbell and Yousef Bozorgnia; and I.M. Idriss.
Role of this project in supporting PEER’s vision

Estimation and characterization of seismic ground motion at structure sites (seismic hazard) is a key component of performance–based earthquake engineering. Ground motion attenuation models describing median estimates and uncertainty of peak ground acceleration, peak ground velocity, peak ground displacement, and response spectral values at various periods of vibration, are a vital element of the ground motion estimation and characterization process. The NGA project integrates the results of comprehensive PEER-Lifelines Program research, both completed and ongoing, which develops the scientific knowledge, data bases, statistical analysis techniques, and ground motion modeling methods required to achieve the goal of developing improved ground motion attenuation models.

Methodology employed

During the project, interaction and coordination with and among various groups is essential to assure that the research products are appropriate, that there are not significant gaps, that the work is completed on schedule, and that the developed NGA models are accepted for use by the broad scientific and engineering user community. Achieving this interaction, and adjusting the NGA program as needed based on the input received is a key part of the coordination process. The groups that must be involved in this process include:

  1. the researchers who are developing the data bases and research results from the various tasks
  2. the ground motion attenuation modelers, who will develop the NGA models using the data bases and research results; and
  3. various user and liaison organizations, who will directly or indirectly use the products of the NGA project. A series of workshops and working group meetings are being conducted to achieve the necessary communication, coordination, and consensus.

The coordination task includes the following elements.

  • At the outset of the project, a project work plan was prepared that includes a summary of task elements and a schedule. The NGA model developers were selected in this beginning phase of the project.
  • A 2-day project kickoff meeting was held to present the project plan and obtain input from the participants. Participants include project researchers, developers of attenuation models, user and liaison organizations, and representative of PEER-Core Program and the sponsoring organizations of PEER-Lifelines Program.
  • Quarterly 2-day workshops are being held involving the project participants. The objectives are to discuss data bases and research results relevant to NGA relationship development, review progress, and, as needed, develop recommendations for program adjustments.
  • Ongoing program coordination with and among the various researchers, attenuation relationship developers, and other project participants occur at working group meetings between quarterly workshops to discuss databases and research results and plan supplemental work to support NGA relationship development.
  • A 2-day final “Users” Workshop will be conducted to present the NGA project results to user liaison organizations. A workshop proceedings will be prepared. Recommendations for follow-on work will be either presented in the proceedings or in a separate document.

The elements of work for NGA developers of attenuation relationships include: participation in the kickoff meeting, quarterly workshops, and the final workshop; participation in working groups as required for NGA relationship development; development of NGA attenuation relationships for response spectral values; peak ground acceleration, peak ground velocity, and peak ground displacement of ground motions; and preparation of reports documenting the NGA models including the bases for modeling decisions.

Brief description of past year’s accomplishments and more detail on expected Year 6 accomplishments

To date, project coordination has been an integral part of the planning and holding of the kickoff meeting (October 2002) and first and second workshops (February and May 2003); the formation and initiation of activities of six working groups who are planning and evaluating research and databases in support of NGA relationship development; and the planning and review of research and database development activities for scope, completeness, and timely delivery of results to project participants. Project coordination will continue in these areas for the duration of the project in accordance with the overall plan for project activities.

Attenuation relationship developers have fully participated in the kickoff meeting, workshops, and in working groups. They will continue to participate in workshops and working groups and will begin more intensive work on development of attenuation relationships following the October 2003 workshop.

Other similar work being conducted within and outside PEER and how this project differs

The NGA project is unique in providing a focused synergistic effort to integrate the latest scientific knowledge and research results, a comprehensive database, advanced statistical analysis techniques, and ground motion modeling methods to develop a next generation of ground motion attenuation relationships.

Plans for Year 7 if this project is expected to be continued

The NGA project is scheduled to be completed by the end of June 2004. At present, there are no specific plans for project continuation beyond that date.

Describe any instances where you are aware that your results have been used in industry


Expected milestones

Major milestones for the coordination effort are the scheduled workshops, each of which has objectives to present and discuss databases and research results that are needed as input to the development of NGA relationships. The final coordination milestone is completion of the Users Workshop in June 2004. Major milestones for attenuation relationship developers are initial completion of NGA relationships, scheduled for January 2004, and final completion of NGA relationships and report documentation, scheduled for April 2004.


The main project deliverable for NGA developers are the final NGA models as documented in the final report of each developer team, scheduled to be completed by April 2004. For the coordination task, interim deliverables are the reports of the conclusions of the kickoff meeting and workshops. The final coordination task deliverable will be the proceedings of the Users Workshop in June 2004, which will describe and compare the NGA models for the benefit of the user community and provide recommendations for follow-on research.