Nath et al. 2012

class openquake.hazardlib.gsim.nath_2012.NathEtAl2012Lower

Implements GMPE of Nath et. al (2012) for intraplate margin seismicity in the Shillong Plateau of India at 25-45 km deph.

This model is based on stochastic simulation with a mean stress drop of 150 bars.

Verification of mean value data was done by digitizing Figure 11 using http://arohatgi.info/WebPlotDigitizer/app/. Note that this independent verification did not include magnitude dependence or standard deviations.

Reference

Page number citations in this documentation refer to:

Nath, S. K., Thingbaijam, K. K. S., Maiti, S. K., and Nayak, A. (2012). Ground-motion predictions in Shillong region, northeast India. Journal of Seismology, 16(3):475–488.

COEFFS_BEDROCK = <openquake.hazardlib.gsim.base.CoeffsTable object>

Coefficients taken from Table 5, p. 483.

DEFINED_FOR_INTENSITY_MEASURE_COMPONENT = 'Vertical'

In simulations only the vertical component is estimated (see p. 479) and the stochastic dataset is what the GMPE is based on, so this model effectively predicts vertical motions.

DEFINED_FOR_INTENSITY_MEASURE_TYPES = set([<class 'openquake.hazardlib.imt.PGA'>, <class 'openquake.hazardlib.imt.PGV'>, <class 'openquake.hazardlib.imt.SA'>])

Set of intensity measure types this GSIM can calculate. A set should contain classes from module openquake.hazardlib.imt.

DEFINED_FOR_STANDARD_DEVIATION_TYPES = set(['Total'])

The only sigma is reported in the main coefficient table, Table 5 on p. 483, and must be the total standard deviation.

DEFINED_FOR_TECTONIC_REGION_TYPE = 'Subduction Interface'

“studies on micro-earthquakes indicated that reverse faulting is predominant in the region” (p. 476)

REQUIRES_DISTANCES = set(['rrup'])

It is noted that “r_rup is the fault-rupture distance in kilometers” following equation (11) on p. 484.

REQUIRES_RUPTURE_PARAMETERS = set(['mag'])

Sole required rupture parameter is magnitude, since faulting style is not addressed.

REQUIRES_SITES_PARAMETERS = set([])

Required site parameter Vs30 is used to determing the NEHRP site class, and thus to choose site amplification coefficients and site amplification stanard error from Table 5 on p. 208.

get_mean_and_stddevs(sites, rup, dists, imt, stddev_types)

See superclass method for specification of input and result values.

Implements equation (11) on p. 484:

ln(P) = c1 + c2*M + c3*(10 - M)^3 + c4*ln(R + c5*exp(c6*M)

class openquake.hazardlib.gsim.nath_2012.NathEtAl2012Upper

Implements GMPE of Nath et. al (2012) for intraplate margin seismicity in the Shillong Plateau of India above 25 km deph.

This model is based on stochastic simulation with a mean stress drop of 40 bars.

COEFFS_UPPER = <openquake.hazardlib.gsim.base.CoeffsTable object>

Coefficients taken from Table 6, p. 485.

get_mean_and_stddevs(sites, rup, dists, imt, stddev_types)

See superclass method for specification of input and result values.

Implements the correction factor for the upper crust, equation (12) on p. 484:

P' = P x Correction_factor