Implements GMPE developed by G. R. Toro, N. A. Abrahamson, J. F. Sneider and published in “Model of Strong Ground Motions from Earthquakes in Central and Eastern North America: Best Estimates and Uncertainties” (Seismological Research Letters, Volume 68, Number 1, 1997) as utilized by the National Seismic Hazard Mapping Project (NSHMP) for the 2008 US hazard model.
This class replicates the algorithm for the Toro et. al. 1997 GMPE as coded in the subroutine getToro in the hazgridXnga2.f Fortran code available at: http://earthquake.usgs.gov/hazards/products/conterminous/2008/software/
The class assumes rupture magnitude to be in Mblg scale (given that MFDs for central and eastern US are given in this scale). The equation implements also the finite-fault correction as given in “Modification of the Toro et al. 1997 Attenuation Equations for Large Magnitudes and Short Distances” (available at: http://www.riskeng.com/downloads/attenuation_equations). The correction uses Mw. Therefore Mblg is converted to Mw using both the Atkinson & Boore 1987 and Johnston 1996 conversion equations and an average correction term is computed.
Coefficients are given for the B/C site conditions.
Coefficient table obtained from coefficient arrays (tb1, tb2, tb3, tb4, tb5, tb6, tbh) defined from line 1596 - 1614 in hazgridXnga2.f
Supported intensity measure component is the geometric mean of attr:~openquake.hazardlib.const.IMC.AVERAGE_HORIZONTAL,
Supported intensity measure types are spectral acceleration, and peak ground acceleration
Supported standard deviation type is only total.
Supported tectonic region type is stable continental crust, given that the equations have been derived for central and eastern north America
Required distance measure is rjb
Required rupture parameter is only magnitude (Mblg).
No site parameters required
See superclass method for spec of input and result values.
Extend ToroEtAl1997MblgNSHMP2008 but assumes magnitude to be in Mw scale.
Coefficients are Mw-specific and no magnitude conversion is considered to take into account finite-fault correction.
Coefficient table obtained from coefficient arrays (tc1, tc2, tc3, tc4, tc5, tc6, th) defined in subroutine getToro in hazgridXnga2.f