Overview of NGA Database Model Development to Date

Overview of NGA Database, Model Development to Date, and Next Steps PEER-NGA Workshop April 12, 2005

NGA Database Overview • 173 earthquakes • ~ 1600 strong-motion stations • 3547 recordings

NGA Database Overview • Metadata – Earthquake Source • Basic source parameters (hypocenter, magnitude, strike, dip, rake, …. . • Finite source parameters (fault length and width) – Distance measures – Footwall/hanging – Directivity parameters – Recording Site • Site location, owner, Station ID number, geology, …… • Soil condition – Geomatrix’s classifications – Vs 30 (measured or inferred)

Previous Data New EQ Data - Kobe - Kocaeli - Chi - Duzce - Hector Mine - Denali

NGA Database Overview Ground Motion Data – Processed time histories (baseline corrected and filtered) – Rotation to strike-normal and strike-parallel directions – Ave. horizontal component at random orientation • Defined as the 50 th percentile value of the geometric mean over the non-redundant 90 degree range of rotation (Dave Boore, 2005) – Time histories and response spectra

NGA Database Overview • Flatfile – A table of selected metadata and response spectra – New version of flatfile in mid March • Ave. horizontal component with random orientation • Fault normal and fault parallel components • Closest distance to the seismogenic zone

NGA Database Overview • NGA data on PEER’s web site (Debra Bartling) – Prototype on http: //peer. berkeley. edu/nga/search. html – For trial use • Searchable • Content of flatfile • Time history data file – Documentation will be added later – Feedbacks to PEER

Model Development • Preliminary model for PGA and pseudo spectral acceleration at 0. 1, 0. 2, 0. 5, 1, and 3 seconds – Changes since last December • Chance to give developers feedbacks before models are finalized

Next Steps • Workshop #9, September 21, 2005 – Final NGA models for • Ave. horizontal component, with directivity effect • Strike-normal and strike-parallel components • USGS ground motion workshop (October 2005) – Reviews and discussions of NGA models