Database of Ground Motions For NGA East

A Presentation by Chris Cramer

at the Stakeholder NGA East Workshop

NIST Gaithersburg, MD

March 7, 2008

Overview

• Goal

• Previous Work

• Tasks

• Summary

Goal

Develop a database of Stable Continental Region ground motions from Eastern North America and around the world for a broad range of geologic site conditions for use in developing Next Generation Attenuation (NGA) relations that compliment the recently developed PEER Center Active Tectonic Region NGA relations.

Key

Gather representative ground motion and geologic data for thin and thick soil conditions over hard rock, as well as hard rock sites, from Stable Continental Regions worldwide.

Previous Work

Databases (Not Data Sources)

• LDEO/NCEER StrongMo Database– Online, Searchable, Waveforms available– Only pre-1990 (not actively maintained or added to)

• Atkinson and Boore, 2006 Electronic Supplement– Table– Hard Rock, Eastern Canada Only

• PEER NGA Database– Online, Searchable, Waveforms available– Parameter Table Available for Attenuation Relation

Developers – Active Tectonic Regions Only

No Stable Continental Region Database Available

• Needed Parameters for NGA Development

• Current

• Worldwide

• Accessible Online

Tasks

General Steps

• Database Design

• Data Gathering

• Data Processing

• Data Simulation*

• Data Distribution

Database Design• Based on PEER NGA Model:

– Database of Waveforms and Metadata (Station, Earthquake, Record, Geology, etc. information)

– Parameter Flat File for Developers (i.e., PGA, PGV, PGD, Sa at 102 periods, and earthquake, station, seismological, and geotechical information)

• Input from NGA East Participants (November 29, 2007 Workshop) and colleagues (2007 ES-SSA and Fall AGU meetings)

Data Gathering

• Geotechnical Data– General Geology (Q, T, M, etc.)– Regional Information (reference Vs

profiles, depth-to-bedrock)– Site-Specific Profiles

• Available Profiles (Memphis, Charleston, St. Louis, Evansville, some owners)

• Measurements at Important Stations*

Data Gathering

• Waveforms (Broadband and Accelerometer) [Largest M down to M3]– Eastern North America

• IRIS Data Center• Canadian National Data Center• LDEO/NCEER StrongMo Database• Others (CERI, COSMOS, etc.)

– International*• Europe• India (some data at CERI, COSMOS)• Australia

Data Processing• Develop Processing and Quality Control

Standards and Procedures with aid of Advisory Committee– Instrument Correction, Waveform Filtering– Acceleration, Velocity, Displacement– Response and Fourier Spectra– Extraction of Specified Parameters (Seismological and

Geotechnical)

• Apply to gathered data and load results into database and then flat file for NGA East developers

Data Simulation

• Extend database to be sure needed site conditions (Vs30s), distances, and magnitudes are represented for NGA East relation development*

Data Distribution

• Flat file to NGA East developers

• Website for access to ground motion database and flat file*

Summary

Conclusions

• Development of a Stable Continental Regions database of ground motions for representative site conditions is crucial for the development of NGA relations for central and eastern US as none is currently available.

• National and international support and cooperation will be required for successful development of this NGA East database.