Raghukanth & Iyengar 2007

class openquake.hazardlib.gsim.raghukanth_iyengar_2007.RaghukanthIyengar2007

Implements GMPE of Raghukanth & Iyengar (2007) for stable continental regions of peninsular India.

This model is intended to be used to predict ground motions in peninsular India, a stable continental region with nonetheless significant seismic hazard (see Section 1 “Introduction”, p. 199 and Section 2 “Seismological model”, p. 200)

Page number citations in this documentation refer to:

Raghukanth, S. and Iyengar, R. (2007). Estimation of seismic spectral acceleration in peninsular India. Journal of Earth System Science, 116(3):199–214.

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

Coefficients taken from Table 3, p. 205.

COEFFS_NEHRP = {'A': <openquake.hazardlib.gsim.base.CoeffsTable object at 0x7f5c9b146510>, 'C': <openquake.hazardlib.gsim.base.CoeffsTable object at 0x7f5c9b146190>, 'B': <openquake.hazardlib.gsim.base.CoeffsTable object at 0x7f5c9b146890>, 'D': <openquake.hazardlib.gsim.base.CoeffsTable object at 0x7f5c9b146550>}

Site class coefficients taken from Table 5, p. 208.

DEFINED_FOR_INTENSITY_MEASURE_COMPONENT = 'Average horizontal'

This is not clear in the paper, but Figure 7 shows the model “compared with the average of the response spectrum of the two horizontal components” of a particular recording. AVERAGE_HORIZONTAL, see p. 211.

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

Although “the coefficients of [equation (1)] are obtained from the simulated database of SA by a two-step stratified regression following Joyner and Boore (1981)” (p. 203), the standard deviations of the intermediate steps are not reported, so only total standard deviation is supported.

DEFINED_FOR_TECTONIC_REGION_TYPE = 'Stable Shallow Crust'

Supported tectonic region type is ‘stable continental’ since peninsular India “is similar to many other stable continental regions (SCR) of the world” (p. 200).

REQUIRES_DISTANCES = set(['rhypo'])

Required distance measure is hypocentral distance, see p. 203.

REQUIRES_RUPTURE_PARAMETERS = set(['mag'])

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

REQUIRES_SITES_PARAMETERS = set(['vs30'])

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 the following equations:

Equation (8) on p. 203 for the bedrock ground motion:

ln(y_br) = c1 + c2*(M - 6) + c3*(M - 6)**2 - lnR - c4*R + ln(ε_br)

Equation (9) on p. 207 gives the site amplification factor:

ln(F_s) = a1*y_br + a2 + ln(δ_site)

Equation (10) on p. 207 for the ground motion at a given site:

y_site = y_br*F_s

Equation (11) on p. 207 for total standard error at a given site:

σ{ln(ε_site)} = sqrt(σ{ln(ε_br)}**2 + σ{ln(δ_site)}**2)

get_nehrp_classes(sites)

Site classification threshholds from Section 4 “Site correction coefficients” p. 205. Note that site classes E and F are not supported.

is_bedrock(sites)

A threshhold is not explicitly defined but the intention can be inferred from the statement that “The above results are valid at the bedrock level, with Vs nearly equal to 3.6 km/s.” p. 203

non_verified = True

Verification of mean value data was done by digitizing Figures 3 and 5 using http://arohatgi.info/WebPlotDigitizer/ app/. Maximum error was relatively high, approximately 10%, but could be reduced to approximately 1.5% by making the following changes to what may be typographical errors in the published coefficients. In each case the value sugstituted is interpolated from neighbouring values.

RaghukanthIyengar2007 COEFFS_BEDROCK (Table 3) at 1.200 s:

• change c1 from 0.2904 to 0.1904

RaghukanthIyengar2007 COEFFS_NEHRP_C (Table 5) at 0.750 s:

• change a1 from 0.36 to -0.30

RaghukanthIyengar2007Southern COEFFS_BEDROCK (Table 2(b)) at 2.000 s:

• change c4 from 0.0001 to 0.0010

Note that these would be in addition to the following more obvious correction which was implemented.

RaghukanthIyengar2007Southern COEFFS_BEDROCK (Table 2(b)) at 0.150 s:

• change c1 from .1941 to 2.1941

Note that since test data was dervied from Figures 3 and 5, PGA is not covered.

class openquake.hazardlib.gsim.raghukanth_iyengar_2007.RaghukanthIyengar2007KoynaWarna

Implements GMPE of Raghukanth & Iyengar (2007) for the Koyna-Warna region of India.

The Koyna-Warna region is defined for the purpose of this GMPE by Figure 2. It is approximately a circle of 2° radius centered on 17°N 75°E.

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

Coefficients taken from Table 2(a), p. 202.

class openquake.hazardlib.gsim.raghukanth_iyengar_2007.RaghukanthIyengar2007Southern

Implements GMPE of Raghukanth & Iyengar (2007) for southern India.

Southern India is defined for the purpose of this GMPE by Figure 2, p. 201. It is that part of India which is south of a line from from approximately 22°N 72°E to 17°N 83°E and excluding the Koyna-Warna region, approximately a circle of 2° radius centered on 17°N 75°E.

Note that in Table 2(b) coefficient c1 at 0.150 s is inexplicably missing the digit before the decimal point. This was assumed to be “2”.

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

Coefficients taken from Table 2(b), p. 203.

class openquake.hazardlib.gsim.raghukanth_iyengar_2007.RaghukanthIyengar2007WesternCentral

Implements GMPE of Raghukanth & Iyengar (2007) for western-central India.

Western-central India is defined for the purpose of this GMPE by Figure 2, p. 201. It is that part of India which is north of a line from from approximately 22°N 72°E to 17°N 83°E.

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

Coefficients taken from Table 2(c), p. 204.