07/19/04NGA Workshop: Fling1 Progress Report on Fling Processing Baseline correction Boore’s method (with judgement) Fling model and removal Sine-Pulse model with 3 parameters Minimal effect on SA (T < 10 s)

07/19/04NGA Workshop: Fling2 To model fling we need to accurately recover the residual displacement. Baseline correction of recorded motion is important step. t 1 : acc > 50 cm/sec 2 t 2 (1): Boore v 0 t 2 (2): acc < 50 cm/sec 2 t 2 (3): 2 x t 2 (2) – t 1

07/19/04NGA Workshop: Fling3 Boore’s t 2 tends to give reliable results Unrealistic results omitted (by judgement) Still non-unique (but little significance on fling removal)

07/19/04NGA Workshop: Fling4 Fix T f (pulse period) using numerical simulations, then solve for t 1 (start time)

07/19/04NGA Workshop: Fling5 Simulated Near-fault Displacements for Chi-Chi EQ Measure time between 10% and 90% of final displacement, adjust to sine pulse to determine T f

07/19/04NGA Workshop: Fling6 Sine-pulse fit and corrected displacement for TCU052 (090)

07/19/04NGA Workshop: Fling7 Sine-pulse fit and corrected displacement for TCU068 (000)

07/19/04NGA Workshop: Fling8 Sine-pulse fit and corrected displacement for TCU068 (090)

07/19/04NGA Workshop: Fling9 Conclusions Baseline correction must be done with care. Sine-pulse model for fling provides time domain parameterization and can be related to underlying physical processes - residual displacement (D): fault offset - pulse period (T f ): slip rise time Need to explore possible physical constraints on pulse start time (t 1 ) - S wave arrival?

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