The high frequency decay parameter κ has been considered as one of the important parameters required in the simulation of earthquake strong ground motions necessary for the proper evaluation of seismic hazard of a region. The present study estimated “ κ” for the highly seismic active region of North East India. The spectral analysis of 598 accelerograms of 32 earthquakes has been done using [1] approach for this purpose. The average values of “ κ” have been found to be 0.049, 0.047 and 0.040 for L-, T- and V-component respectively. The distance dependence of κ is not significant in the region. The κ 0 ( κ at R = 0) for soft rock stations is found to be more than those of hard rock sites in consistent with other similar studies. The correlation between “ κ” and earthquake magnitude at most of the stations for the region under study is not significant which indicates that κ depends on the site conditions in the region. The κ values estimated in the present study are useful for the evaluation of seismic hazard of the region.
The spectral shape of earthquake strong ground motions plays an important role in the simulation of realistic accelerograms using different techniques. The simulated accelerograms are crucial for the proper evaluation of seismic hazard of a region. Different factors including attenuation, velocity and site conditions etc. control the spectral characteristics of the strong ground motions. It has been suggested that the spectrum of strong ground motion from earthquakes is flat above the corner frequency [
[
A = A 0 e − π f ; f > f E (1)
where A0 depends on the source, epicentral distance and other factors, fE is the frequency above which the spectral amplitude follows an exponential decay. The studies have been done to attribute the origin of “k” to source, site and/or path attenuation. [
In spite of the lack of agreement on the physical origin of “k”, it has been widely used in number of seismological applications like computation of site amplification factors, ground motion prediction equations [
In the present study, the high frequency decay parameter “k” has been estimated at different sites and source-receiver distances for the region of North East India. The possible dependence of “k” on distance for hard rock sites and soft soil sites has been investigated. The dependence of “k” on earthquake size has also been examined.
The tectonic map of the NE India region has been shown in
Barapani Shear region, and Mikir Hills, Dhubri, Sylhet and Duaki faults, and Dudhnai and Kulsi faults. The alignment of Kopili fault in NW-SE direction and in North Dhansiri fault separates Mikir Hills from Shillong highlands [
A strong motion accelerographs network has been installed in the region by Department of Earthquake Engineering, Indian Institute of Technology, Roorkee with the objectives of studying the strong ground motions characteristics for earthquake engineering purposes. The 598 accelerograms of 32 earthquakes (mb 3.9 - 6.8) recorded at this network has been used in the present analysis.
Different techniques have been reported in the literature to estimate “k” including use of displacement spectra [
ln A = ln A 0 − π к f (2)
This a linear equation between “lnA” and frequency “f”. The “k” can be estimated from the slope (m) of the line (Equation (2)) as:
к = − m / k (3)
The following procedure has been adopted for the estimation of “k”:
1) First the S-wave portion of the accelerogram is selected.
2) Fourier transform of the selected wave has been obtained using FFT and plotted the same on log-linear scale i.e. with a logarithmic y-axis (amplitude) and a linear x-axis (frequency).
3) Two frequencies have been selected by visual inspection of the spectrum of S-waves: first at the start of linear downward trend in the spectrum (f1) and second at the end of linear downward trend (f2). The visual inspection of S-wave spectrum in selecting the two frequencies is preferred over the automatic procedure as f1 and f2 vary from record to record. The visual inspection avoids the biased estimates of “k”. This procedure has been used in previous studies also (e.g. [
4) A line has fitted between f1 and f2 in a least square sense on log-linear plot. The slope (m) of the line gives the value of “k” (Equation (3)).
The values of “k” have been estimated for the three components (N-S, E-W and Z) of the recorded accelerograms using the procedure described above.
Sr. no | YYYY | MM | DD | LAT.(N) | LON.(E) | MW | Depth(Km) | Stations | Ns |
---|---|---|---|---|---|---|---|---|---|
1 | 1986 | 09 | 10 | 25.38 | 92.07 | 5.2 | 43 | BAIT, DAUK, KHLI, NONK, NONP, NONS, PANI, PYNU, SAIT, UMMU, UMRO, UMSN | 12 |
2 | 1987 | 05 | 18 | 25.27 | 94.20 | 5.7 | 49 | BAIT, BAMU, BERL, BOKA, DIPU, GUNJ, HAFL, HAJA, HATI, LAIS, NONP, PANI, SAIT, UMRO | 14 |
3 | 1988 | 02 | 06 | 24.64 | 91.51 | 5.8 | 33 | BAIG, BAIT, BAMU, DAUK, GUNJ, HAFL, HATI, KATA, KHLI, MAWP, NONK, NONP, PYNU, SAIT, SHIL, UNMU, UMRO, UMSN | 18 |
4 | 1988 | 08 | 06 | 25.14 | 95.12 | 6.8 | 91 | BAIG, BAIT, BAMU, BERL, BOKA, CHER, DAUK, DIPU, DOLO, GUNJ, HAJA, HARE, HOJA, JELA, JHIR, KALA, KATA, KHLI, KOOM, LOHA, MAWK, MAWP, MAWS, NONK, SILC, UMMU, UMRO, UMSN | 28 |
5 | 2008 | 03 | 13 | 26.6 | 91.8 | 4.0 | 33 | MNGB, MORB | 2 |
6 | 2008 | 05 | 29 | 26.6 | 91.8 | 4.2 | 33 | MNGB, MORB | 2 |
7 | 2008 | 12 | 25 | 27.2 | 87.9 | 4.4 | 33 | GANG | 1 |
8 | 2009 | 02 | 15 | 26.0 | 90.2 | 4.4 | 39.3 | BARP, BONG, DHBR, KOKJ, TURA | 5 |
9 | 2009 | 02 | 24 | 25.9 | 94.3 | 4.8 | 10 | DIPU, GOLA, LKHM | 3 |
10 | 2009 | 08 | 11 | 24.4 | 94.8 | 5.6 | 22 | BOKO, BONG, DIPU, GOLP, GWAT, HALK, KARM, KOKJ, NONG, SILC, TEJP, TURA | 12 |
11 | 2009 | 08 | 19 | 26.6 | 92.5 | 4.9 | 20 | BOKO, GWAT | 2 |
12 | 2009 | 08 | 30 | 25.4 | 94.8 | 5.3 | 85 | BOKO, DIPU, GWAT, LKHP, TURA | 5 |
13 | 2009 | 09 | 03 | 24.3 | 94.6 | 5.9 | 100 | BOKO, BONG, DIPU, GOLP, GWAT, HKDI, NONS, SILC, TURA | 9 |
14 | 2009 | 09 | 21 | 27.3 | 91.5 | 6.2 | 8.0 | BOKO, BONG, COVB, DRJL, DIPU, GANG, GOLP, GWAT, KOKJ, NAUG, NONS, LKHP, TEJP | 13 |
15 | 2009 | 10 | 29 | 26.6 | 90.0 | 4.2 | 90 | BONG, GOLP, KOKJ, NONS, TURA | 5 |
16 | 2009 | 10 | 29 | 27.3 | 91.4 | 5.2 | 5.0 | BONG, GOLP, KOKJ, NONG, TURA | 5 |
17 | 2009 | 12 | 29 | 24.5 | 94.8 | 5.5 | 80 | BONG, GOLP, GWAT, HKDI , TEJP, TURA | 6 |
18 | 2009 | 12 | 31 | 27.3 | 91.4 | 5.5 | 7.0 | BONG, GOLP, GWAT, KOKJ, TURA | 5 |
19 | 2010 | 02 | 26 | 28.5 | 86.7 | 5.4 | 28 | BONG, DRJL, GANG, GOLP, GWAT, KOKJ, SILI | 7 |
20 | 2010 | 03 | 12 | 23.0 | 96.0 | 5.6 | 96 | BONG, GOLP, GWAT, HALK, TURA | 5 |
21 | 2010 | 09 | 11 | 25.9 | 90.2 | 5.0 | 20 | BONG, GWAT, KOKJ | 3 |
22 | 2010 | 12 | 12 | 25.0 | 93.3 | 4.8 | 15 | KRMJ, NAUG | 2 |
23 | 2011 | 02 | 04 | 24.8 | 94.6 | 6.4 | 30 | COVB, GWAT, JORH, JOWI, KOKJ, NAUG, SIBS | 7 |
---|---|---|---|---|---|---|---|---|---|
24 | 2011 | 09 | 18 | 27.6 | 88.2 | 6.8 | 10 | CHAN, CHPW, COVB, GANG, KRMJ, KOKJ, MALD, NAUG, PATI, RAXL, SIBS, SILI, UDHM | 13 |
25 | 2011 | 09 | 18 | 27.6 | 88.5 | 5.0 | 16 | COVB, GANG | 2 |
26 | 2011 | 09 | 18 | 27.5 | 88.4 | 4.5 | 9 | GANG | 1 |
27 | 2011 | 09 | 18 | 27.6 | 88.4 | 4.2 | 28 | GANG | 1 |
28 | 2011 | 09 | 22 | 27.6 | 88.4 | 3.9 | 30 | GANG | 1 |
29 | 2011 | 11 | 21 | 25.1 | 95.3 | 5.8 | 80 | GWAT | 1 |
30 | 2012 | 05 | 11 | 26.6 | 93.0 | 5.4 | 20.0 | GOLA, JORH, KOKJ | 3 |
31 | 2012 | 07 | 10 | 26.5 | 93.2 | 4.5 | 56 | NAUG | 1 |
32 | 2012 | 07 | 14 | 25.5 | 94.2 | 5.5 | 35 | GOLA, JORA, NAUG | 3 |
It has been found that f1 lies in the range 2-13 Hz while f2 is in the range 20 - 28 Hz. The estimated values of “k” corresponding to three components for the earthquakes and recording stations are given in
The distance dependence of k has been analyzed using the following linear model [
к = к 0 + к R (4)
where k0 is the value of k at distance R = 0. This model has been used in many studies due to its simplicity of formulation (e.g. [
к = 0.037 + 0.0000158 R For vertical component
and
к = 0.041 + 0.0000326 R For horizontal component
We note that distance dependence for both the components is not significant. The values of k0 as 0.041 (horizontal component) and 0.037 (vertical component) represent the overall value for the region. The difference in these two values indicates that site response is different for different components as has been observed in site amplification studies. The estimate of k0 (vertical) is useful along with H/V ratio for the first order estimation of site effect where site-specific borehole data is not available as suggested by [
к = 0.034 + 0.0000158 R For hard rock sites
and
к = 0.037 + 0.000024 R For soft rock sites
The k0 for soft rock stations is found to be more than those of hard rock sites. The ratio of k0 for soft rock to hard rock is equal to 1.09. Similar observations have been found to be in different studies for other regions. [
Sr. no. | Date of Event | Station | Kappa-L | SD | Kappa-T | SD | Kappa-V | SD | Geology |
---|---|---|---|---|---|---|---|---|---|
1 | 1986/09/10 | BAIT | 0.031 | 0.0051 | 0.011 | 0.0049 | 0.015 | 0.0039 | Soft soil |
DAUK | 0.053 | 0.0048 | 0.050 | 0.0048 | 0.037 | 0.0044 | Soft soil | ||
KHLI | 0.035 | 0.0046 | 0.033 | 0.0056 | 0.037 | 0.0052 | Hard rock | ||
NONK | 0.021 | 0.0050 | 0.028 | 0.0055 | 0.020 | 0.0036 | Hard rock | ||
NONP | 0.021 | 0.0032 | 0.014 | 0.0031 | 0.051 | 0.0057 | Hard rock | ||
NONS | 0.023 | 0.0033 | 0.029 | 0.0048 | 0.033 | 0.0040 | Hard rock | ||
PANI | 0.031 | 0.0032 | 0.018 | 0.0033 | 0.039 | 0.0062 | Hard rock | ||
PYNU | 0.036 | 0.0031 | 0.023 | 0.0045 | 0.019 | 0.0056 | Hard rock | ||
SAIT | 0.024 | 0.0037 | 0.026 | 0.0041 | 0.027 | 0.0041 | Soft soil | ||
UMMU | 0.035 | 0.0032 | 0.024 | 0.0041 | 0.043 | 0.0061 | Hard rock | ||
UMRO | 0.036 | 0.0055 | 0.027 | 0.0047 | 0.027 | 0.0056 | Soft soil | ||
UMSN | 0.013 | 0.0051 | 0.014 | 0.0044 | 0.030 | 0.0038 | Hard rock | ||
2 | 1987/05/18 | BAIT | 0.027 | 0.0032 | 0.023 | 0.0035 | 0.020 | 0.0049 | Soft soil |
BAMU | 0.024 | 0.0052 | 0.028 | 0.0062 | 0.034 | 0.0056 | Soft soil | ||
BERL | 0.036 | 0.0061 | 0.029 | 0.0057 | 0.024 | 0.0052 | Soft soil | ||
BOKA | 0.019 | 0.0040 | 0.034 | 0.0046 | 0.017 | 0.0048 | Soft soil | ||
DIPU | 0.042 | 0.0072 | 0.039 | 0.0070 | 0.028 | 0.0049 | Soft soil | ||
GUNJ | 0.031 | 0.0050 | 0.038 | 0.0048 | 0.027 | 0.0073 | Soft soil | ||
HAFL | 0.030 | 0.0039 | 0.029 | 0.0035 | 0.039 | 0.0073 | Soft soil | ||
HAJA | 0.026 | 0.0055 | 0.028 | 0.0054 | 0.029 | 0.0063 | Soft soil | ||
HATI | 0.032 | 0.0048 | 0.022 | 0.0045 | 0.027 | 0.0039 | Soft soil | ||
LAIS | 0.15 | 0.005 | 0.036 | 0.0037 | 0.043 | 0.0046 | Hard rock | ||
NONP | 0.022 | 0.0042 | 0.023 | 0.0040 | 0.041 | 0.0068 | Hard rock | ||
PANI | 0.032 | 0.0066 | 0.033 | 0.0068 | 0.030 | 0.0092 | Hard rock | ||
SAIT | 0.030 | 0.0075 | 0.022 | 0.0072 | 0.032 | 0.0119 | Soft soil | ||
UMRO | 0.053 | 0.0074 | 0.034 | 0.0063 | 0.033 | 0.0084 | Soft soil | ||
3 | 1988/02/06 | BAIG | 0.043 | 0.0049 | 0.041 | 0.0047 | 0.031 | 0.0072 | Soft soil |
BAIT | 0.052 | 0.0051 | 0.038 | 0.0047 | - | - | Soft soil | ||
BAMU | 0.028 | 0.0043 | 0.027 | 0.0048 | 0.051 | 0.0071 | Soft soil | ||
DAUK | 0.034 | 0.0040 | 0.033 | 0.0039 | 0.023 | 0.0080 | Soft soil | ||
GUNJ | 0.035 | 0.0037 | 0.033 | 0.0037 | 0.034 | 0.0052 | Soft soil | ||
HAFL | 0.026 | 0.0033 | 0.033 | 0.0035 | 0.043 | 0.0086 | Soft soil | ||
HATI | 0.034 | 0.0051 | 0.034 | 0.0045 | 0.036 | 0.0090 | Soft soil | ||
KATA | 0.012 | 0.0035 | 0.028 | 0.0031 | 0.035 | 0.0033 | Soft soil | ||
KHLI | 0.033 | 0.0059 | 0.034 | 0.0048 | 0.053 | 0.0084 | Hard rock | ||
MAWP | 0.019 | 0.0051 | 0.016 | 0.0048 | 0.032 | 0.0104 | Hard rock | ||
NONK | 0.040 | 0.0045 | 0.036 | 0.0038 | 0.015 | 0.0039 | Hard rock | ||
NONP | 0.034 | 0.0070 | 0.026 | 0.0064 | 0.050 | 0.0059 | Hard rock |
PYNU | 0.041 | 0.0047 | 0.040 | 0.0059 | 0.014 | 0.0052 | Hard rock | ||
---|---|---|---|---|---|---|---|---|---|
SAIT | 0.027 | 0.0038 | 0.023 | 0.0055 | 0.015 | 0.0049 | Soft soil | ||
SHIL | 0.033 | 0.0050 | 0.029 | 0.0046 | 0.024 | 0.0053 | Hard rock | ||
UMMU | 0.045 | 0.0109 | 0.060 | 0.0134 | 0.049 | 0.0124 | Hard rock | ||
UMRO | 0.037 | 0.0048 | 0.033 | 0.0035 | 0.041 | 0.0050 | Soft soil | ||
UMSN | 0.017 | 0.0040 | 0.019 | 0.0033 | 0.024 | 0.0043 | Hard rock | ||
4 | 1988/08/06 | BAIG | 0.056 | 0.0053 | 0.018 | 0.0051 | - | - | Soft soil |
BAIT | 0.019 | 0.0040 | 0.019 | 0.0035 | 0.012 | 0.0126 | Soft soil | ||
BAMU | 0.026 | 0.0042 | 0.022 | 0.0036 | 0.033 | 0.0045 | Soft soil | ||
BERL | 0.034 | 0.0040 | 0.021 | 0.0032 | 0.021 | 0.0035 | Soft soil | ||
BOKA | 0.017 | 0.0039 | 0.007 | 0.0039 | 0.005 | 0.0035 | Soft soil | ||
CHER | 0.034 | 0.0037 | 0.032 | 0.0040 | 0.013 | 0.0034 | Hard rock | ||
DAUK | 0.036 | 0.0030 | 0.040 | 0.0034 | 0.021 | 0.0041 | Soft soil | ||
DIPU | 0.026 | 0.0039 | 0.029 | 0.0036 | 0.047 | 0.0116 | Soft soil | ||
DOLO | 0.036 | 0.0037 | 0.042 | 0.0036 | 0.016 | 0.0043 | Soft soil | ||
GUNJ | 0.027 | 0.0033 | 0.026 | 0.0042 | 0.027 | 0.0049 | Soft soil | ||
HAJA | 0.046 | 0.0102 | 0.033 | 0.0083 | 0.027 | 0.0074 | Soft soil | ||
HARE | 0.031 | 0.0040 | 0.036 | 0.0037 | 0.027 | 0.0039 | Soft soil | ||
HOJA | 0.021 | 0.0037 | 0.034 | 0.0057 | 0.014 | 0.0067 | Soft soil | ||
JELA | 0.042 | 0.0047 | 0.045 | 0.0051 | 0.037 | 0.0043 | Soft soil | ||
JHIR | 0.038 | 0.0047 | 0.042 | 0.0056 | 0.034 | 0.0062 | Soft soil | ||
KALA | 0.036 | 0.0047 | 0.042 | 0.0056 | 0.034 | 0.0062 | Soft soil | ||
KATA | 0.074 | 0.0097 | 0.074 | 0.0098 | 0.035 | 0.0050 | Soft soil | ||
KHLI | 0.024 | 0.0073 | 0.022 | 0.0115 | 0.026 | 0.0045 | Hard rock | ||
KOOM | 0.036 | 0.0041 | 0.045 | 0.0061 | 0.040 | 0.0057 | Soft soil | ||
LOHA | 0.041 | 0.0052 | 0.034 | 0.0057 | 0.029 | 0.0043 | Soft soil | ||
MAWK | 0.040 | 0.0082 | 0.029 | 0.0073 | 0.007 | 0.0105 | Hard rock | ||
MAWP | 0.026 | 0.0040 | 0.038 | 0.0037 | 0.018 | 0.0048 | Hard rock | ||
MAWS | 0.016 | 0.0031 | 0.015 | 0.0041 | 0.025 | 0.0062 | Hard rock | ||
NONK | 0.026 | 0.0032 | 0.030 | 0.0029 | 0.013 | 0.0056 | Hard rock | ||
NONS | 0.030 | 0.0081 | 0.042 | 0.0064 | 0.054 | 0.0071 | Hard rock | ||
PANI | 0.045 | 0.0087 | 0.020 | 0.0096 | 0.021 | 0.0048 | Hard rock | ||
PYNU | 0.035 | 0.0068 | 0.062 | 0.0082 | 0.019 | 0.0094 | Hard rock | ||
SAIT | 0.025 | 0.0048 | 0.022 | 0.0069 | 0.020 | 0.0108 | Soft soil | ||
SHIL | 0.028 | 0.0071 | 0.013 | 0.0082 | 0.046 | 0.0115 | Hard rock | ||
SILC | 0.039 | 0.0061 | 0.038 | 0.0054 | 0.035 | 0.0061 | Soft soil | ||
UMMU | 0.041 | 0.0084 | 0.044 | 0.0104 | 0.022 | 0.0143 | Hard rock | ||
UMRO | 0.040 | 0.0061 | 0.039 | 0.0052 | 0.029 | 0.0043 | Soft soil | ||
UMSN | 0.026 | 0.0077 | 0.011 | 0.0076 | 0.022 | 0.0089 | Hard rock | ||
5 | 2008/03/13 | MNG | 0.044 | 0.0047 | 0.038 | 0.0038 | 0.024 | 0.0042 | Soft soil |
MOR | 0.036 | 0.0037 | 0.028 | 0.0042 | 0.017 | 0.0056 | Soft soil |
6 | 2008/05/29 | MNG | 0.039 | 0.0034 | 0.036 | 0.0052 | 0.030 | 0.0048 | Soft soil |
---|---|---|---|---|---|---|---|---|---|
MOR | 0.024 | 0.0041 | 0.028 | 0.0050 | 0.021 | 0.0053 | Soft soil | ||
7 | 2008/12/25 | GANG | 0.062 | 0.0068 | 0.081 | 0.0050 | 0.045 | 0.0073 | Hard rock |
8 | 2009/02/15 | BARP | 0.134 | 0.0195 | 0.116 | 0.157 | 0.020 | 0.0217 | Soft soil |
BONG | 0.036 | 0.043 | 0.034 | 0.061 | 0.049 | 0.0071 | Soft soil | ||
DHBR | 0.051 | 0.0050 | 0.054 | 0.0049 | 0.051 | 0.0058 | Soft soil | ||
KOKJ | 0.055 | 0.0089 | 0.030 | 0.0054 | 0.025 | 0.0129 | Soft soil | ||
TURA | 0.063 | 0.0067 | 0.067 | 0.0055 | 0.067 | 0.0067 | Soft soil | ||
9 | 2009/02/24 | DIPU | 0.024 | 0.0056 | 0.035 | 0.0058 | 0.025 | 0.0042 | Soft soil |
GOLA | 0.051 | 0.0081 | 0.043 | 0.0075 | 0.030 | 0.0068 | Soft soil | ||
LKHM | 0.075 | 0.0081 | 0.076 | 0.0069 | 0.045 | 0.0095 | Soft soil | ||
10 | 2009/08/11 | BOKO | 0.046 | 0.0069 | 0.036 | 0.0069 | 0.017 | 0.0061 | Soft soil |
BONG | 0.061 | 0.0073 | 0.067 | 0.0057 | 0.061 | 0.0065 | Soft soil | ||
DIPU | 0.054 | 0.0066 | 0.049 | 0.0054 | 0.032 | 0.0064 | Soft soil | ||
GOLP | 0.070 | 0.0090 | 0.053 | 0.0082 | 0.057 | 0.0059 | Soft soil | ||
GWAT | 0.037 | 0.0052 | 0.044 | 0.0050 | 0.062 | 0.0059 | Soft soil | ||
HALK | 0.121 | 0.0097 | 0.136 | 0.0093 | 0.104 | 0.0116 | Soft soil | ||
KARM | 0.109 | 0.0073 | 0.112 | 0.0087 | 0.062 | 0.0068 | Soft soil | ||
KOKJ | 0.049 | 0.0052 | 0.042 | 0.0057 | 0.044 | 0.0074 | Soft soil | ||
NONG | 0.031 | 0.0051 | 0.017 | 0.0053 | 0.017 | 0.0053 | Hard rock | ||
SILC | 0.105 | 0.0079 | 0.110 | 0.0094 | 0.058 | 0.0046 | Soft soil | ||
TEJP | 0.030 | 0.0065 | 0.029 | 0.0066 | 0.028 | 0.0076 | Soft soil | ||
TURA | 0.063 | 0.0069 | 0.063 | 0.0061 | 0.053 | 0.0056 | Soft soil | ||
11 | 2009/08/19 | BOKO | 0.029 | 0.0037 | 0.049 | 0.0039 | 0.025 | 0.0036 | Soft soil |
GUAT | 0.043 | 0.0031 | 0.041 | 0.0032 | 0.046 | 0.0035 | Soft soil | ||
12 | 2009/08/30 | BOKA | 0.029 | 0.0033 | 0.031 | 0.0034 | 0.020 | 0.0041 | Soft soil |
DIPU | 0.039 | 0.0037 | 0.041 | 0.0032 | 0.027 | 0.0026 | Soft soil | ||
GUA | 0.049 | 0.0036 | 0.048 | 0.0038 | 0.052 | 0.0040 | Soft soil | ||
LKH | 0.047 | 0.0037 | 0.054 | 0.0038 | 0.032 | 0.0036 | Soft soil | ||
TURA | 0.055 | 0.0031 | 0.059 | 0.0034 | 0.051 | 0.0036 | Soft soil | ||
13 | 2009/09/03 | BOKA | 0.026 | 0.0030 | 0.020 | 0.0037 | 0.007 | 0.0042 | Soft soil |
BONG | 0.052 | 0.0037 | 0.048 | 0.0047 | 0.068 | 0.0045 | Soft soil | ||
DIPU | 0.038 | 0.0042 | 0.034 | 0.0045 | 0.033 | 0.0037 | Soft soil | ||
GOLP | 0.027 | 0.0032 | 0.039 | 0.0035 | 0.032 | 0.0044 | Soft soil | ||
GUA | 0.042 | 0.0042 | 0.032 | 0.0040 | 0.036 | 0.0040 | Soft soil | ||
HKD | 0.090 | 0.0042 | 0.105 | 0.0041 | 0.061 | 0.041 | Soft soil | ||
NONS | 0.030 | 0.0046 | 0.023 | 0.0044 | 0.046 | 0.0045 | Hard rock | ||
SILC | 0.079 | 0.0039 | 0.087 | 0.0043 | 0.052 | 0.0054 | Soft soil | ||
TURA | 0.053 | 0.0043 | 0.039 | 0.0042 | 0.037 | 0.0039 | Soft soil | ||
14 | 2009/09/21 | BOKO | 0.051 | 0.0047 | 0.054 | 0.0033 | 0.042 | 0.0038 | Soft soil |
BONG | 0.062 | 0.0041 | 0.070 | 0.0040 | 0.057 | 0.0041 | Soft soil |
COBV | 0.086 | 0.0037 | 0.075 | 0.0036 | 0.063 | 0.0050 | Soft soil | ||
---|---|---|---|---|---|---|---|---|---|
DJL | 0.071 | 0.0040 | 0.095 | 0.0050 | 0.062 | 0.0045 | Hard rock | ||
DIPU | 0.055 | 0.0041 | 0.072 | 0.0039 | 0.056 | 0.0039 | Soft soil | ||
GANG | 0.067 | 0.0032 | 0.078 | 0.0039 | 0.051 | 0.0039 | Hard rock | ||
GOLP | 0.068 | 0.0033 | 0.065 | 0.0045 | 0.062 | 0.0040 | Soft soil | ||
GUAT | 0.051 | 0.0050 | 0.041 | 0.0051 | 0.058 | 0.0043 | Soft soil | ||
KOKJ | 0.048 | 0.0036 | 0.053 | 0.0046 | 0.063 | 0.0047 | Soft soil | ||
NAUG | 0.070 | 0.0028 | 0.075 | 0.0030 | 0.069 | 0.0036 | Soft soil | ||
NONS | 0.057 | 0.0044 | 0.051 | 0.0049 | 0.074 | 0.0062 | Hard rock | ||
LKH | 0.076 | 0.0050 | 0.095 | 0.0039 | 0.061 | 0.0048 | Soft soil | ||
TEJP | 0.064 | 0.0037 | 0.065 | 0.0065 | 0.064 | 0.0046 | Soft soil | ||
15 | 2009/10/29 | BONG | 0.066 | 0.0063 | 0.076 | 0.0073 | 0.063 | 0.0048 | Soft soil |
GOLP | 0.092 | 0.0051 | 0.082 | 0.0060 | 0.065 | 0.0047 | Soft soil | ||
KOKJ | 0.078 | 0.0068 | 0.070 | 0.0069 | 0.037 | 0.0050 | Soft soil | ||
NONS | 0.078 | 0.0079 | 0.076 | 0.0079 | 0.065 | 0.0069 | Hard rock | ||
TURA | 0.111 | 0.0096 | 0.118 | 0.0091 | 0.123 | 0.0084 | Soft soil | ||
16 | 2009/10/29 | BONG | 0.050 | 0.0051 | 0.066 | 0.0050 | 0.066 | 0.0044 | Soft soil |
GOLP | 0.029 | 0.0097 | 0.022 | 0.0060 | 0.031 | 0.0103 | Soft soil | ||
KOKJ | 0.030 | 0.0064 | 0.018 | 0.0072 | 0.035 | 0.0132 | Soft soil | ||
NONS | 0.068 | 0.0054 | 0.058 | 0.0058 | 0.049 | 0.0049 | Hard rock | ||
TURA | 0.055 | 0.0063 | 0.052 | 0.0062 | 0.037 | 0.0053 | Soft soil | ||
17 | 2009/12/29 | BONG | 0.061 | 0.0058 | 0.055 | 0.0049 | 0.081 | 0.0076 | Soft soil |
GOLP | 0.066 | 0.0062 | 0.037 | 0.0091 | 0.051 | 0.0054 | Soft soil | ||
GWAT | 0.051 | 0.0068 | 0.036 | 0.0054 | 0.084 | 0.0067 | Soft soil | ||
HALK | 0.104 | 0.0053 | 0.101 | 0.0066 | - | - | Soft soil | ||
TEJP | 0.023 | 0.0055 | 0.028 | 0.0046 | 0.041 | 0.0050 | Soft soil | ||
TURA | 0.040 | 0.0057 | 0.040 | 0.0075 | 0.038 | 0.0045 | Soft soil | ||
18 | 2009/12/31 | BONG | 0.058 | 0.0056 | 0.063 | 0.0068 | 0.058 | 0.0048 | Soft soil |
GOLP | 0.056 | 0.0054 | 0.043 | 0.0047 | 0.057 | 0.0050 | Soft soil | ||
GWAT | 0.034 | 0.0061 | 0.035 | 0.0064 | 0.046 | 0.0052 | Soft soil | ||
KOKJ | 0.061 | 0.0053 | 0.071 | 0.0056 | 0.066 | 0.0059 | Soft soil | ||
TURA | 0.094 | 0.0050 | 0.091 | 0.0063 | 0.080 | 0.0042 | Soft soil | ||
19 | 2010/02/26 | BONG | 0.082 | 0.0067 | 0.070 | 0.0049 | 0.066 | 0.0051 | Soft soil |
DRJL | 0.062 | 0.0059 | 0.044 | 0.0054 | 0.031 | 0.0061 | Hard rock | ||
GANG | 0.069 | 0.0047 | 0.057 | 0.0070 | 0.014 | 0.0060 | Hard rock | ||
GOLP | 0.084 | 0.0047 | 0.087 | 0.0051 | 0.067 | 0.0051 | Soft soil | ||
GWAT | 0.069 | 0.0068 | 0.070 | 0.0057 | 0.063 | 0.0062 | Soft soil | ||
KOKJ | 0.063 | 0.0069 | 0.082 | 0.0064 | 0.033 | 0.0056 | Soft soil | ||
SILI | 0.070 | 0.0053 | 0.072 | 0.0056 | 0.025 | 0.0060 | Soft soil | ||
20 | 2010/03/12 | BONG | 0.041 | 0.0044 | 0.052 | 0.0052 | 0.076 | 0.0059 | Soft soil |
GOLP | 0.069 | 0.0121 | 0.060 | 0.0062 | 0.055 | 0.0084 | Soft soil |
GWAT | 0.028 | 0.0047 | 0.027 | 0.0071 | 0.061 | 0.0074 | Soft soil | ||
---|---|---|---|---|---|---|---|---|---|
HALK | 0.095 | 0.0052 | 0.101 | 0.0056 | 0.030 | 0.0052 | Soft soil | ||
TURA | 0.062 | 0.0054 | 0.064 | 0.0055 | 0.054 | 0.0060 | Soft soil | ||
21 | 2010/09/11 | BONG | 0.032 | 0.0065 | 0.042 | 0.0048 | 0.049 | 0.0050 | Soft soil |
GWAT | 0.033 | 0.0044 | 0.033 | 0.0055 | 0.051 | 0.0046 | Soft soil | ||
KOKJ | 0.042 | 0.0059 | 0.044 | 0.0049 | 0.073 | 0.0048 | Soft soil | ||
22 | 2010/12/12 | KRMJ | 0.132 | 0.0077 | 0.144 | 0.0099 | 0.091 | 0.0078 | Soft soil |
NAUG | 0.060 | 0.0061 | 0.057 | 0.0058 | 0.049 | 0.0063 | Soft soil | ||
23 | 2011/02/04 | COVB | 0.059 | 0.0091 | 0.047 | 0.0082 | 0.038 | 0.0066 | Soft soil |
GWAT | 0.044 | 0.0040 | 0.034 | 0.0069 | 0.049 | 0.0047 | Soft soil | ||
JORH | 0.045 | 0.0039 | 0.035 | 0.0046 | 0.016 | 0.0050 | Soft soil | ||
JOWI | 0.049 | 0.0076 | 0.065 | 0.0073 | 0.011 | 0.0058 | Soft soil | ||
KOKJ | 0.030 | 0.0049 | - | - | 0.033 | 0.0057 | Soft soil | ||
NAUG | 0.029 | 0.0047 | 0.034 | 0.0047 | 0.028 | 0.0052 | Soft soil | ||
24 | 2011/09/18 | CHAM | 0.064 | 0.0057 | 0.093 | 0.0067 | 0.040 | 0.0048 | Hard rock |
CHPW | 0.081 | 0.0081 | 0.102 | 0.0093 | 0.019 | 0.0056 | Hard rock | ||
COVB | 0.069 | 0.0045 | 0.056 | 0.0043 | 0.037 | 0.0063 | Soft soil | ||
GANG | 0.057 | 0.0056 | 0.050 | 0.0061 | 0.046 | 0.0053 | Hard rock | ||
KRMJ | 0.078 | 0.0055 | 0.084 | 0.0077 | 0.102 | 0.0084 | Soft soil | ||
KOKJ | 0.055 | 0.0063 | 0.054 | 0.0062 | 0.049 | 0.0080 | Soft soil | ||
MALD | 0.058 | 0.0044 | 0.060 | 0.0044 | 0.077 | 0.0068 | Soft soil | ||
NAUG | 0.062 | 0.0061 | 0.067 | 0.0044 | 0.053 | 0.0052 | Soft soil | ||
PATI | 0.057 | 0.0086 | 0.081 | 0.0068 | 0.070 | 0.0071 | Hard rock | ||
RAXL | 0.083 | 0.0039 | 0.061 | 0.0037 | 0.022 | 0.0061 | Soft soil | ||
SIBS | 0.097 | 0.0077 | 0.098 | 0.0077 | - | - | Soft soil | ||
SILI | 0.079 | 0.0064 | 0.095 | 0.0074 | 0.032 | 0.0080 | Soft soil | ||
UDHM | 0.093 | 0.0067 | 0.077 | 0.0072 | 0.047 | 0.0064 | Soft soil | ||
25 | 2011/09/18 | COVB | 0.069 | 0.0066 | 0.097 | 0.0091 | 0.060 | 0.0075 | Soft soil |
GANG | 0.072 | 0.0058 | 0.032 | 0.0082 | 0.032 | 0.0076 | Hard rock | ||
26 | 2011/09/18 | GANG | 0.062 | 0.0054 | 0.054 | 0.0048 | 0.062 | 0.0101 | Hard rock |
27 | 2011/09/18 | GANG | 0.036 | 0.0053 | 0.041 | 0.0047 | 0.019 | 0.0071 | Hard rock |
28 | 2011/09/22 | GANG | 0.039 | 0.0051 | 0.028 | 0.0055 | 0.028 | 0.0062 | Hard rock |
29 | 2011/11/21 | GWAT | 0.035 | 0.0098 | 0.035 | 0.0098 | 0.017 | 0.0078 | Soft soil |
30 | 2012/05/11 | GOLA | 0.072 | 0.0186 | 0.026 | 0.0124 | 0.049 | 0.0153 | Soft soil |
JORH | 0.039 | 0.0085 | 0.040 | 0.0065 | 0.023 | 0.0070 | Soft soil | ||
KOKJ | 0.049 | 0.0057 | 0.043 | 0.0054 | 0.027 | 0.0058 | Hard rock | ||
31 | 2012/07/10 | NAUG | 0.045 | 0.0062 | 0.041 | 0.0085 | 0.057 | 0.0084 | Soft soil |
32 | 2012/07/14 | GOLA | 0.042 | 0.0051 | 0.033 | 0.0049 | 0.030 | 0.0063 | Soft soil |
JORH | 0.070 | 0.0053 | 0.072 | 0.0040 | 0.045 | 0.0044 | Soft soil | ||
NAUG | 0.035 | 0.0042 | 0.036 | 0.0058 | 0.047 | 0.0072 | Soft soil |
Sr. no. | Region | Kappa Value | Reference No. |
---|---|---|---|
1 | North-eastern Sonora | 0.04 | [ |
2 | California | 0.05 | [ |
3 | France | 0.04 | [ |
4 | Switzerland | 0.015 | [ |
5 | Western Alps | 0.012 | [ |
6 | Central Europe (Germany) | 0.05 | [ |
7 | Guerrero Mexico | 0.045 | [ |
8 | Greece | 0.06 | [ |
9 | Eastern Canada & Western Canada | 0.04 | [ |
10 | Southern California | 0.06 | [ |
11 | North-East Himalaya | 0.049 (L-comp), 0.047 (T-comp) and 0.040 (V-comp) | This study |
[
rock site in the Kachchh region of Gujarat, India.
The dependence of kappa values on earthquake size has been examined by plotting the estimated k values with earthquake magnitudes for the stations where sufficient number of earthquake have been recorded.
The average value of k estimated from the spectral analysis of horizontal components of 598 accelerograms for NE India region has been found to be in the range 0.047 - 0.049 and 0.040 for vertical component. The distance dependence of k is not significant. The k0(soft site)/k0(rock site) ratio is found to be 1.09. The analysis shows that k is not dependent on the magnitude but dependent on site-condition in the region for the range of magnitudes studies here. The study presents the k model for NE India region which is first study of its kind in the region. The inferences drawn about k in the NE region are based on the data available for the analysis. The same may be validated further as and when more data is available. With more data, the spatial distribution may also be investigated in the region. The other methods reported in the literature may also be applied to estimate k in the region.
The estimated values of k are useful in the studies of Ground Motion Prediction Equations (GMPE) as well as for the simulation of earthquake strong ground motions in the seismically active NE region. Thus this study is important for bearing on the seismic hazard studies of the region.
The authors are thankful to their respective organizations for support. The authors are very grateful to Dr. RBS Yadav for his kind help in this research. The waveform of events has been downloaded from the site http://www.pesmos.in. The authors are thankful to the reviewers and the editor for their extremely constructive comments which helped in improving the manuscript significantly.
Yadav, R., Kumar, D. and Chopra, S. (2018) The High Frequency Decay Parameter k (Kappa) in the Region of North East India. Open Journal of Earthquake Research, 7, 141-159. https://doi.org/10.4236/ojer.2018.72009