A Seismic Hazard Assessment of North Chhattisgarh (India)

Abstract

Chhattisgarh, located in Central India, has been carved out of Madhya Pradesh to become the 26th state of the Indian Union. North Chhattisgarh is addressed by the tribal population. In the current study, an endeavor has been made to carry out the seismic hazard analysis for the major district headquarters of north Chhattisgarh, considering the local site effects and developing a seismic zone map for north Chhattisgarh. Seismic hazard analysis has been done for major district headquarters Ambikapur, Baikunthpur [Koria], Korba, and Jashpurnagar of north Chhattisgarh, using seismotectonic information. All earthquake sources and past seismic events have been considered within a radius of 300 km for the headquarters, applying deterministic and probabilistic seismic hazard analysis approaches. The seismic parameters and peak ground acceleration at the bedrock level for the district headquarters of north Chhattisgarh have been estimated. Using probabilistic seismic hazard analysis, hazard curves have been developed for each district headquarters. Alternatively, for peak ground acceleration of 0.05 g, 0.1 g, and 0.15 g return periods have been estimated for the study area. The probabilities of exceedance for 2% and 10% for 50 years have also been estimated for the study area. The current study throws light on the design and construction of vital civil engineering structures near and around the seismically active headquarters in northern Chhattisgarh.

1. Introduction

Over recent years, there has been an explosive growth of interest in the development of novel gel-phase materials based on small molecules. The occurrence of a major earthquake event is still seen as a catastrophe, with devastating consequences over human lives, buildings, and transportation networks, causing a large-scale impact on any society. Indeed, even if becoming particularly devastating to poor, underdeveloped countries, it equally affects populations and several infrastructures in modern, industrialized countries. For global picture, the occurrence of earthquakes can have an outcome, which is reflected in the deep changes in building philosophy or large investments in seismic design strategies. A number of recent earthquakes are typically referred to not due to only their destructive impact but also owing to the lessons that have been learned, leading, and sometimes to reflect changes or the establishment of turning points in seismic design philosophies. Chhattisgarh (21°17′ 42.47″ N, 81° 49′ 41.63′ E) is a newly developed state in India. North Chhattisgarh is rich in temples, natural beauty, dense forests, hill stations, water bodies, and industries. The northern portion of the state includes major districts that are Ambikapur, Baikunthpur [Koria], Korba, and Jashpurnagar. India’s National Center for Seismology (NCS) and USGS reported a magnitude 4.8 earthquake near Ambikāpur, Surguja district of Chhattisgarh, in the morning on Monday, July 11th, 2022, at a moderately shallow depth. On the same date, earthquake of magnitude 4.3 is reported near Korba district. Further on an earthquake of magnitude of 4.6 on 29 July 2022 is reported by National Center for Seismology, near Baikunthpur [Koria]. Recent seismic activity around the districts of north Chhattisgarh is increased. It is essential that the current study is focused on the seismic vulnerability analysis over the major district headquarters of the north Chhattisgarh region.

2. Methodology

For estimating the seismic hazard at places of critical infrastructures, such as high-rise building, dams, bridges, and subsea tunnels, are of the utmost importance in the field of earthquake engineering, as damage to such structures results in severe economic loss and threats to the environment. Seismic hazard can be quantified by adopting two globally accepted techniques: the deterministic seismic hazard analysis (DSHA) and the probabilistic seismic hazard analysis (PSHA). Both approaches can be defined in a four-step process, and their initial steps are identical [1]. In the deterministic approach, the ground-shaking hazard at any point is evaluated based on the controlling source, which is expected to produce the maximum hazard at that point among all the potential sources [2]. On the other hand, in the probabilistic approach, the inherent uncertainties in the forecast of earthquake size, site, and earth motion parameters are explicitly combined to obtain the hazard for a given probability of exceedance in a particular time period [3]. Despite their benefits and drawbacks, these two methods can harmonize each other and give additional insights into the question of seismic hazard [4]. Moreover, a deterministic framework accounts for the hazard from each source independently; thus, it is more capable in the regions, where seismic activity is low to moderate, particularly, where limited earthquake data is available [5].

2.1 Deterministic seismic hazard analysis (DSHA)

For identification of linear seismic sources, a seismotectonic atlas developed by the Survey of India [6] has been taken as the base for the present study. The seismotectonic maps are prepared for each district headquarters of north Chhattisgarh, keeping the headquarter at the center of the circle, with a radius of 300 km, based on the latitude and longitude as shown in Figure 1. The faults having fault length (Li) ≥ 25 km coming in a 300 km radius were identified, numbered, and measured the length of the faults. The minimum map distances of identified faults were measured from the center of the circle for the study area.

Figure 1.

Seismotectonic map of district headquarters of north Chhattisgarh: (a) Ambikapur, (b) Baikunthpur [Koria], (c) Korba, and (d) Jashpurnagar.

The total number of linear sources as 33, 36, 41, and 27 were identified for major districts Ambikapur, Baikunthpur [Koria], Korba, and Jashpurnagar, respectively. In next step, the source-to-site distance or minimum map distance for the above linear sources for study area was measured using seismotectonic maps as shown in Figure 1 and tabulated in Appendix Tables A1–A4.

For estimation of seismic parameters, the linear least-square fit method developed by Stepp [7] has been applied over the past earthquake data collected from various catalog and research agencies (USGS website and NICE) for all four-district headquarters of north Chhattisgarh. In order to assess the magnitude of completeness, time-magnitude plots of the final catalog have been generated for different time periods as shown in Figure 2.

Figure 2.

Earthquake data completeness analysis for district headquarters of north Chhattisgarh: (a) Ambikapur, (b) Baikunthpur [Koria], (c) Korba, and (d) Jashpurnagar.

The seismic activity of a region is characterized by the Gutenberg-Richter [8], recurrence relation as given below:

$$log10\left(\mathrm{N}\right)=\mathrm{a}–\mathrm{b}\mathrm{Mw}$$E1

where N is the number of earthquakes greater than or equal to magnitude m, a denotes the seismicity rate computed by the logarithm of the average number of earthquakes of magnitude M_min or M_max, and b value characterizes the proportion of large earthquakes relative to small earthquakes [9] as shown in Figure 3. For tectonic earthquakes, the b value is to be confined within the range 0.7018 < b < 0.8429 as tabulated in Table 1.

Figure 3.

Frequency-magnitude relationship for district headquarters of north Chhattisgarh: (a) Ambikapur, (b) Baikunthpur [Koria], (c) Korba, and (d) Jashpurnagar.

Name of district headquarter	regional recurrence relationship for district headquarter	b value considered for the present study
Ambikapur	Log 10 (N) = 3.9917–0.7197 Mw	0.7197
Baikunthpur [Koria]	Log 10 (N) = 4.3785–0.7817 Mw	0.7817
Korba	Log 10 (N) = 4.6665–0.8429 Mw	0.8429
Jashpurnagar	Log 10 (N) = 3.8666–0.7018 Mw	0.7018

Table 1.

Regional recurrence relationship and “b” values for district headquarters of north Chhattisgarh.

The “b” value assesses the frequency of the occurrence of earthquakes of different sizes. The maximum magnitude is the highest potential of accumulated strain energy to be released in the region or in a seismic source [10]. The maximum probable earthquake is defined as the upper limit of earthquake magnitude for a given entire region and is synonymous with the magnitude of the largest possible earthquake in that region [11]. It assumes a sharp cut-off magnitude at a maximum magnitude, so by definition, no earthquake is to be expected with a magnitude exceeding M_max [12]. In the present study, M_max is estimated by using two methods. The first method is of Wells and Coppersmith [13] and the second method is of Gupta [14]. In Wells and Coppersmith method, a relation between M_w and surface rupture length (SRL) was developed using reliable source parameters, and this is further applicable to all types of faults, shallow earthquakes, and interplate or intraplate earthquakes.

$$\mathrm{Log}\left(\mathrm{SRL}\right)=0.57{\mathrm{M}}_{\mathrm{w}}-2.33$$E2

The above equation was used to estimate the maximum magnitude (Mmax) for all sources of the study area. Gupta’s method in which maximum magnitude (Mmax) was estimated from Eq. (3) as given below:

$${\mathrm{M}}_{\max }={\mathrm{M}}_{\mathrm{obs}+}0.5$$E3

M_max = Maximum magnitude

M_obs = Observed magnitude

After comparing the outcome of the above two methods, maximum magnitude (M_max) values for seismic sources for the district headquarters of north Chhattisgarh are tabulated in Appendix A. The recurrence relation developed in the present study is not for the particular seismic source but for the entire study region. It is required to differentiate the activity rates among the seismic sources and to develop the frequency magnitude relationship for an individual fault. The truncated exponential recurrence relationship is commonly used in practice: to estimate the most likely earthquake magnitude and the most likely source-site distance, for the calculation of PGA values using the ground motion records [15]. This process of disaggregation requires the mean annual rate of exceedance (λm), expressed as a function of magnitude. A MATLAB computer program has been developed to solve Eq. (4) and the graphs were plotted as shown in Figure 4.

Figure 4.

Disaggregation of seismic sources near district headquarters: (a) Ambikapur, (b) Baikunthpur [Koria], (c) Korba, and (d) Jashpurnagar.

$${\lambda }_m=w_i\ast \upsilon \ast \frac{exp[-\beta \left(m-m_0\right)-exp\left[-\beta \left(m_{\max }-m_0\right)\right]}{1-exp\left[-\beta \left(m_{\max }-m_0\right)\right]}$$E4

where $\upsilon =exp\left(\alpha -\beta \ast m_0\right)$ α = 2.303*a, β = 2.303*b, and w_i is the weight factor for a particular source.

An attenuation relationship includes the source geometry, earthquake magnitude, source-to-site distance, and site conditions. Regional geology plays an important role in the selection of an appropriate relationship in any seismic hazard study. In the recent past, devastating events have occurred in Peninsular India (PI), which is a warning about the possibility of such earthquakes in future [16]. In the present research, the study area comes under the region of PI. So, the attenuation relationship developed by Iyengar and Raghu Kanth [17] has been used. The GMPE proposed by Iyengear and Raghu Kanth is given below:

$$ln\mathrm{Y}=\text{C1}+\text{C2}\left(\mathrm{M}-6\right)+\text{C3}{\left(\mathrm{M}-6\right)}^2–ln\left(\mathrm{R}\right)–\text{C4}\left(\mathrm{R}\right)+ln\left(\mathrm{\epsilon }\right)$$E5

where Y, M, and R refer to PGA(g), moment magnitude, and hypo-central distance, respectively.

Peninsular India: C1 = 1.6858; C2 = 0.9241; C3 = −0.0760; C4 = 0.0057;

σ (ln ε) = standard deviation of error = 0 [50 Percentile, for DSHA ε = 0]

σ (ln ε) = standard deviation of error = 0.4648 [84 Percentile]

M100 = magnitude of earthquake [100 years Recurrence—period calculated by using Figure 4] R = hypo-central distance = √ (D²+F²) D = minimum map distance to the sources, and F = focal depth = 10 km.

The peak ground acceleration at bedrock level for all the sources of the study area has been estimated for a return period of 100 years, using the attenuation relationship of Iyengear and Raghu Kanth [17]. The estimated peak ground acceleration values at bedrock level of seismic sources of the district headquarters of north Chhattisgarh are tabulated in Appendix Tables B1–B4. It is observed that in the attenuation relationship the highest estimated PGA (g) value is found for fault no. F8 for district headquarter Baikunthpur [Koria] and tabulated in Table 2.

Name of district headquarter	Hypo-central distance	Magnitude M100	PGA(g) value
			50 percentile	84 percentile
Ambikapur; Fault No. F7	14.366	4.741	0.09587	0.15259
Baikunthpur [Koria]; Fault No. F8	17.598	5.338	0.14554	0.23165
Korba; Fault No. F6	92.803	4.910	0.01144	92.803
Jashpurnagar; Fault No. F9	109.015	6.709	0.04929	0.07846

Table 2.

Maximum PGA values for seismic sources for district headquarters of north Chhattisgarh.

The seismic zonation map of any country acts as a guide to the seismic status of the regions and their susceptibility to earthquakes. India has been divided into five zones with respect to the severity of the earthquake. Zone V is the seismically most active zone, where an earthquake of magnitude 8 or more could occur.

Recent strong motion observations around the world have revolutionized the thinking on the aspect of the design of engineering structures, placing emphasis on the characteristics of the structures. BIS 1893 (Part 1): 2016 (sixth revision) [18], prepared a seismic zone map of India as shown in Figure 5 with zone factors that are tabulated in Table 3.

Figure 5.

Indian seismic zone map as per BIS 189 (Part 1): 2016 [Map taken from BIS 1893 (Part 1): 2016, sixth revision].

Seismic zone	II	III	IV	V
Seismic intensity	Low	Moderate	Severe	Very severe
Z	0.10	0.16	0.24	0.36

Table 3.

Seismic zone factor, Z, IS 1893 (Part 1): 2016 (Clause 6.4.2).

The outcome of the present study with the recommended value for zone II is 0.1g as per IS 1893 (Part 1): 2016 (sixth revision). The maximum PGA (g) value for 50 percentile for a return period 100 years for Baikunthpur [Koria] is more and is 0.14554 g for Iyengear and Raghu Kanth’s model.

As Figure 6 (i) shows the district headquarters map of Chhattisgarh and the study area is highlighted by a rectangle. Using the outcome of the DSHA approach and IS 1893 (Part 1): 2016 (sixth revision) recommendation the seismic zone map for north Chhattisgarh has been developed and as shown in Figure 7a and b.

Figure 6.

Chhattisgarh district map.

Figure 7.

Seismic zone map of north Chhattisgarh. (a) PGA (g) values for 50 percentile. (b) PGA (g) values for 84 percentile.

2.2 Probabilistic seismic hazard analysis (PSHA)

Thus, seismic hazard estimation has been performed considering the classical Cornell [19] approach. This approach comprises considering all potential seismic sources and their activity rate. Many researchers have considered this approach to carry out the hazard analysis of different regions of India [20, 21, 22, 23, 24, 25, 26, 27]. The seismic hazard curves can be used to evaluate the probability of ground motion exceedance for a specified return period. Seismic hazard curves can be obtained for a particular seismic source and are combined to express aggregate hazards at a particular site. The probability of exceedance can be written as:

$${\lambda }_{y\ast }=\sum _{i=1}^{N_s}{\nu }_i\int \int P\left[Y>y\ast |m,r\right]f_{\mathit{Mi}}\left(m\right)f_{\mathit{Ri}}\left(r\right)\mathit{\text{dmdr}}$$E6

The final PSHA equation is given by

$${\lambda }_{y\ast }=\sum _{i=1}^{N_S}\sum _{j=1}^{N_M}\sum _{k=1}^{N_R}{\nu }_i\int \int P\left[Y>y\ast |m_j,r_k\right]P\left[M=m_j\right]P\left[R=r_k\right]$$E7

where P[Y > y* | m, r] is obtained from the predictive relationship and the probability density functions for magnitude and distance, respectively. The mean annual rate of exceedance λy* is computed at a site for different specified ground motion values y* in a life period of time. A computer program has been developed in MATLAB, which is used to draw the seismic hazard curves for the major district headquarters of north Chhattisgarh. The curves are depicted in Figure 8. Using Iyengear and Raghu Kanth’s [17] attenuation relationship, the peak ground accelerations at bedrock level for 2% and 10% probability of exceedance in 50 years have been computed [28]. The aggregate value of PGA from this relationship has been worked out for each district headquarter (Figure 9). For 2% and 10% probability of exceedance in 50 years the PGA values for district headquarters Korba, Jashpurnagar, Ambikapur, and Baikunthpur [Koria] ranges from 0.016 to 0.086 g and from 0.008 to 0.036 g, respectively. The outcome highlighted that the seismically activity district headquarters are Ambikapur and Baikunthpur [Koria]. Thus, for PGA values 0.05 g, 0.10 g, and 0.015 g at bedrock level, the return periods have been estimated for Ambikapur and Baikunthpur [Koria] and have been tabulated in Table 4.

Figure 8.

Seismic hazard curves for district headquarters of north Chhattisgarh: (a) Ambikapur, (b) Baikunthpur [Koria], (c) Korba, and (d) Jashpurnagar.

Figure 9.

Seismic hazard curves for district headquarters of north Chhattisgarh.

Name of district headquarter	For PGA(g) the return periods in years
	0.05g	0.10g	0.15g
Ambikapur	1017	8788	48781
Baikunthpur [Koria]	614	3848	16364

Table 4.

Return periods for various PGA (g) values for district headquarters of north Chhattisgarh.

3. Conclusions

After carrying out the deterministic and probabilistic seismic hazard analysis for major district headquarters of north Chhattisgarh, considering the local site effects, the following conclusions were drawn and discussed below:

The frequency magnitude relationship was established from the research, for the study area, after carrying out the completeness analysis as per Stepp. Completeness of the data was observed for the north Chhattisgarh region and a seismic hazard parameter of “b value” estimated was found to vary from 0.7018 to 0.8429. The maximum value of peak ground acceleration (PGA) for a recurrence period of 100 years for the headquarter of Ambikapur was found to be due to fault F7 having a fault length of 46 km with a hypo-central distance of 14.366 km, and was 0.09587 g for 50 percentile and 0.15259 g for 84 percentile. On the other hand, the maximum value of peak ground acceleration (PGA), for the recurrence period of 100 years for the headquarter Baikunthpur [Koria], which was found to be due to fault F8, having fault length of 140 km, hypo-central distance of 17.598 km, and was estimated to be equal to 0.14554 g for 50 percentile and 0.23165 g for 84 percentile. For Korba and Jashpurnagar, the peak ground acceleration (PGA) for a recurrence period of 100 years found to be for fault F6, fault length of 46 km, and F9, fault length of 30 km are respectively very low. Using PSHA approach, a seismic hazard curves have been prepared for the major district headquarters of north Chhattisgarh. For Baikunthpur [Koria], the estimated return was found to be a period of 3848 year for 0.1g. The outcome of the present study is directly used for the design of earthquake resistance structures.

A.

Fault No.	Fault length (Li) in km	Mw observed in the fault	Maximum magnitude		Maximum magnitude	Weight factor wi = ${\frac{{\mathrm{L}}_{\mathrm{i}}}{\sum \mathrm{L}}}_{\mathrm{i}}$
			Method A	Method B
F1	51	3.3	4.7	3.8	4.7	0.0293
F2	26	3.3	4.1	3.8	4.1	0.0149
F3	25	4.0	4.1	4.5	4.5	0.0144
F4	28	4.0	4.2	4.5	4.5	0.0161
F5	62	4.0	4.8	4.5	4.8	0.0356
F6	77	4.5	5.0	5.0	5.0	0.0442
F7	46	4.3	4.6	4.8	4.8	0.0264
F8	140	4.5	5.4	5.0	5.4	0.0803
F9	30	4.5	4.3	5.0	5.0	0.0172
F10	30	4.5	4.3	5.0	5.0	0.0172
F11	55	4.5	4.7	5.0	5.0	0.0316
F12	25	4.0	4.1	4.5	4.5	0.0144
F13	39	4.0	4.4	4.5	4.5	0.0224
F14	32	4.2	4.3	4.7	4.7	0.0184
F15	30	4.2	4.3	4.7	4.7	0.0172
F16	117	3.8	5.3	4.3	5.3	0.0671
F17	78	4.5	5.0	5.0	5.0	0.0447
F18	45	6.5	4.6	7.0	7.0	0.0258
F19	28	5.0	4.2	5.5	5.5	0.0161
F20	42	6.5	4.5	7.0	7.0	0.0241
F21	28	6.5	4.2	7.0	7.0	0.0161
F22	47	5.0	4.6	5.5	5.5	0.0270
F23	33	6.7	4.3	7.2	7.2	0.0190
F24	60	6.7	4.8	7.2	7.2	0.0344
F25	51	4.7	4.7	5.2	5.2	0.0293
F26	31	6.7	4.3	7.2	7.2	0.0178
F27	70	6.7	4.9	7.2	7.2	0.0402
F28	70	5.8	4.9	6.3	6.3	0.0402
F29	75	4.4	4.9	4.9	4.9	0.0430
F30	26	4.6	4.1	5.1	5.1	0.0149
F31	86	4.1	5.0	4.6	5.0	0.0493
F32	75	4.6	4.9	5.1	5.1	0.0430
F33	87	5.3	5.1	5.8	5.8	0.0499

Table A1.

Estimation of maximum magnitude for sources for district headquarter Ambikapur.

Fault No.	Fault length (Li) in km	Mw observed in the fault	Maximum magnitude		Maximum magnitude	Weight factor wi = ${\frac{{\mathrm{L}}_{\mathrm{i}}}{\sum \mathrm{L}}}_{\mathrm{i}}$
			Method A	Method B
F1	51	3.3	4.7	3.8	4.7	0.0218
F2	26	3.3	4.1	3.8	4.1	0.0111
F3	25	4.0	4.1	4.5	4.5	0.0107
F4	28	4.0	4.2	4.5	4.5	0.0120
F5	62	4.0	4.8	4.5	4.8	0.0265
F6	77	4.5	5.0	5.0	5.0	0.0329
F7	46	4.3	4.6	4.8	4.8	0.0197
F8	140	4.5	5.4	5.0	5.4	0.0597
F9	30	4.5	4.3	5.0	5.0	0.0128
F10	30	4.5	4.3	5.0	5.0	0.0128
F11	55	4.5	4.7	5.0	5.0	0.0235
F12	78	4.5	5.0	5.0	5.0	0.0333
F13	39	4.0	4.4	4.5	4.5	0.0167
F14	32	4.2	4.3	4.7	4.7	0.0137
F15	30	4.2	4.3	4.7	4.7	0.0128
F16	45	6.5	4.6	7.0	7.0	0.0192
F17	117	4.6	5.3	5.1	5.3	0.0499
F18	42	6.5	4.5	7.0	7.0	0.0180
F19	28	6.5	4.2	7.0	7.0	0.0120
F20	28	5.0	4.2	5.5	5.5	0.0120
F21	47	5.0	4.6	5.5	5.5	0.0201
F22	33	6.7	4.3	7.2	7.2	0.0141
F23	60	6.7	4.8	7.2	7.2	0.0256
F24	70	6.7	4.9	7.2	7.2	0.0299
F25	51	4.7	4.7	5.2	5.2	0.0218
F26	31	6.7	4.3	7.2	7.2	0.0133
F27	76	6.7	4.9	7.2	7.2	0.0324
F28	47	6.7	4.6	7.2	7.2	0.0201
F29	38	6.7	4.4	7.2	7.2	0.0162
F30	477	6.7	6.3	7.2	7.2	0.2034
F31	91	5.8	5.1	6.3	6.3	0.0388
F32	70	5.8	4.9	6.3	6.3	0.0299
F33	58	5.8	4.8	6.3	6.3	0.0248
F34	75	4.6	4.9	5.1	5.1	0.032
F35	26	4.6	4.1	5.1	5.1	0.0111
F36	87	5.3	5.1	5.8	5.8	0.0371

Table A2.

Estimation of maximum magnitude for sources for district headquarter Baikunthpur [Koria].

Fault No.	Fault length (Li) in km	Mw observed in the fault	Maximum magnitude		Maximum magnitude	Weight factor wi = ${\frac{{\mathrm{L}}_{\mathrm{i}}}{\sum \mathrm{L}}}_{\mathrm{i}}$
			Method A	Method B
F1	51	3.3	4.7	3.8	4.7	0.0197
F2	26	3.3	4.1	3.8	4.1	0.0100
F3	25	4.0	4.1	4.5	4.5	0.0097
F4	28	4.0	4.2	4.5	4.5	0.0108
F5	62	4.0	4.8	4.5	4.8	0.0239
F6	46	4.5	4.6	5.0	5.0	0.0177
F7	77	4.5	5.0	5.0	5.0	0.0296
F8	30	4.5	4.3	5.0	5.0	0.0116
F9	30	4.5	4.3	5.0	5.0	0.0116
F10	55	4.5	4.7	5.0	5.0	0.0212
F11	140	4.5	5.4	5.0	5.4	0.0539
F12	78	4.5	5.0	5.0	5.0	0.0300
F13	25	4.0	4.1	4.5	4.5	0.0097
F14	39	4.0	4.4	4.5	4.5	0.0150
F15	117	4.6	5.3	5.1	5.3	0.0450
F16	32	4.2	4.3	4.7	4.7	0.0123
F17	30	4.2	4.3	4.7	4.7	0.0116
F18	45	6.5	4.6	7.0	7.0	0.0173
F19	42	6.5	4.5	7.0	7.0	0.0162
F20	28	6.5	4.2	7.0	7.0	0.0108
F21	28	5.0	4.2	5.5	5.5	0.0108
F22	47	5.0	4.6	5.5	5.5	0.0181
F23	33	6.7	4.3	7.2	7.2	0.0127
F24	51	4.7	4.7	5.2	5.2	0.0197
F25	31	6.7	4.3	7.2	7.2	0.0120
F26	76	6.7	4.9	7.2	7.2	0.0293
F27	47	6.7	4.6	7.2	7.2	0.0181
F28	60	6.7	4.8	7.2	7.2	0.0231
F29	70	6.7	4.9	7.2	7.2	0.0270
F30	38	6.7	4.4	7.2	7.2	0.0147
F31	477	6.7	6.3	7.2	7.2	0.1834
F32	91	5.8	5.1	6.3	6.3	0.0350
F33	70	5.8	4.9	6.3	6.3	0.0270
F34	58	5.8	4.8	6.3	6.3	0.0223
F35	45	5.8	4.6	6.3	6.3	0.0173
F36	25	5.8	4.1	6.3	6.3	0.0097
F37	26	4.6	4.1	5.1	5.1	0.0100
F38	75	4.4	4.9	4.9	4.9	0.0289
F39	75	4.6	4.9	5.1	5.1	0.0289
F40	86	4.1	5.0	4.6	5.0	0.0331
F41	87	5.3	5.1	5.8	5.8	0.0335

Table A3.

Estimation of maximum magnitude for sources for district headquarter Korba.

Fault No.	Fault length (Li) in km	Mw observed in the fault	Maximum magnitude		Maximum magnitude	Weight factor wi = ${\frac{{\mathrm{L}}_{\mathrm{i}}}{\sum \mathrm{L}}}_{\mathrm{i}}$
			Method A	Method B
F1	51	3.3	4.7	3.8	4.7	0.0358
F2	26	3.3	4.1	3.8	4.1	0.0183
F3	25	5.5	4.1	6.0	60	0.0176
F4	39	4.0	4.4	4.5	4.5	0.0274
F5	117	4.6	5.3	5.1	5.3	0.0821
F6	32	4.2	4.3	4.7	4.7	0.0225
F7	30	4.2	4.3	4.7	4.7	0.0211
F8	45	6.5	4.6	7.0	7.0	0.0316
F9	30	4.5	4.3	5.0	5.0	0.0211
F10	30	4.5	4.3	5.0	5.0	0.0211
F11	55	4.5	4.7	5.0	5.0	0.0386
F12	78	4.5	5.0	5.0	5.0	0.0547
F13	77	4.5	5.0	5.0	5.0	0.0540
F14	28	4.0	4.2	4.5	4.5	0.0197
F15	62	4.0	4.8	4.5	4.8	0.0435
F16	46	4.3	4.6	4.8	4.8	0.0323
F17	140	4.5	5.4	5.0	5.4	0.0982
F18	42	6.5	4.5	7.0	7.0	0.0295
F19	28	6.5	4.2	7.0	7.0	0.0197
F20	47	5.0	4.6	5.5	5.5	0.0330
F21	28	5.0	4.2	5.5	5.5	0.0197
F22	75	4.6	4.9	5.1	5.1	0.0526
F23	26	4.6	4.1	5.1	5.1	0.0183
F24	75	4.4	4.9	4.9	4.9	0.0526
F25	86	4.1	5.0	4.6	5.0	0.0604
F26	87	5.3	5.1	5.8	5.8	0.0611
F27	47	3.0	4.6	3.5	4.6	0.0330

Table A4.

Estimation of maximum magnitude for sources for district headquarter Jashpurnagar.

Fault No.	Fault length (Li) in km	Hypo-central distance (R) in km	Magnitude M100 [recurrence period—100 years]	PGA (g)
				50 percentile	84 percentile
F1	51	188.197	4.654	0.00247	0.00393
F2	26	169.283	4.069	0.00154	0.00245
F3	25	109.722	4.436	0.00515	0.00820
F4	28	73.053	4.443	0.00962	0.01530
F5	62	43.964	4.755	0.02688	0.04279
F6	77	55.437	4.946	0.02463	0.03921
F7	46	14.366	4.741	0.09587	0.15259
F8	140	53.374	5.342	0.03930	0.06255
F9	30	85.839	4.874	0.01237	0.01969
F10	30	76.906	4.978	0.01627	0.02589
F11	55	80.845	4.926	0.01430	0.02276
F12	25	163.333	4.434	0.00255	0.00405
F13	39	114.441	4.458	0.00494	0.00785
F14	32	108.345	4.629	0.00656	0.01045
F15	30	101.339	4.625	0.00727	0.01157
F16	117	140.470	5.245	0.00823	0.01309
F17	78	95.004	4.950	0.01152	0.01834
F18	45	96.767	5.996	0.03201	0.05095
F19	28	188.56	5.340	0.00514	0.00818
F20	42	162.653	5.960	0.01266	0.02014
F21	28	181.726	5.760	0.00841	0.01339
F22	47	202.013	5.327	0.00439	0.00698
F23	32	243.519	5.848	0.00480	0.00764
F24	60	276.16	6.179	0.00477	0.00759
F25	51	272.046	5.094	0.00172	0.00273
F26	30	299.432	5.839	0.00282	0.00448
F27	70	294.673	6.255	0.00431	0.00685
F28	70	287.316	5.92	0.00340	0.00540
F29	75	282.662	4.854	0.00120	0.00191
F30	26	230.742	4.936	0.00216	0.00343
F31	86	182.893	4.954	0.00365	0.00580
F32	75	258.258	5.039	0.00184	0.00293
F33	87	213.585	5.638	0.00530	0.00844

Table B1.

PGA values for seismic sources for district headquarter Ambikapur.

Fault No.	Fault length (Li) in km	Hypo-central distance (R) in km	Magnitude M100 [recurrence period—100 Years]	PGA(g)
				50 percentile	84 percentile
F1	51	284.311	4.654	0.00095	0.00151
F2	26	226.875	4.071	0.00083	0.00132
F3	25	159.071	4.436	0.00269	0.00427
F4	28	113.997	4.444	0.00489	0.00778
F5	62	75.268	4.753	0.01311	0.02086
F6	77	61.487	4.946	0.02146	0.03415
F7	46	18.688	4.739	0.07174	0.11419
F8	140	17.598	5.338	0.14554	0.23165
F9	30	113.706	4.872	0.00795	0.01265
F10	30	85.684	4.784	0.01123	0.01788
F11	55	58.705	4.982	0.02374	0.03778
F12	78	70.340	4.948	0.01787	0.02845
F13	39	130.700	4.458	0.00394	0.00627
F14	32	93.850	4.629	0.00823	0.01310
F15	30	76.359	4.623	0.01110	0.01766
F16	45	63.914	5.892	0.05304	0.08443
F17	117	115.568	5.238	0.01144	0.01821
F18	42	125.292	5.852	0.01837	0.02923
F19	28	125.425	5.644	0.01501	0.02389
F20	28	130.393	5.213	0.00908	0.01445
F21	47	143.071	5.310	0.00851	0.01355
F22	32	176.807	5.764	0.00893	0.01420
F23	60	209.857	6.053	0.00817	0.01300
F24	70	228.330	6.142	0.00733	0.01166
F25	51	205.760	5.092	0.00330	0.00525
F26	31	233.794	5.743	0.00478	0.00761
F27	76	240.422	6.146	0.00652	0.01037
F28	47	266.593	5.940	0.00419	0.00667
F29	38	270.842	5.852	0.00371	0.00590
F30	477	268.928	6.860	0.00907	0.01444
F31	91	290.955	5.957	0.00340	0.00541
F32	70	235.202	5.861	0.00528	0.00840
F33	58	257.776	5.808	0.00403	0.00641
F34	75	230.631	5.035	0.00241	0.00383
F35	26	248.655	4.936	0.00181	0.00288
F36	87	275.870	5.624	0.00284	0.00452

Table B2.

PGA values for seismic sources for district headquarter Baikunthpur [Koria].

Fault No.	Fault length (Li) in km	Hypo-central distance (R) in km	Magnitude M100 [recurrence period—100 Years]	PGA(g)
				50 percentile	84 percentile
F1	51	274.332	4.652	0.00104	0.00164
F2	26	260.081	4.074	0.00060	0.00095
F3	25	209.347	4.439	0.00154	0.00244
F4	28	174.787	4.443	0.00225	0.00358
F5	62	141.854	4.751	0.00475	0.00756
F6	46	92.803	4.910	0.01144	0.01820
F7	77	143.137	4.946	0.00579	0.00921
F8	30	186.156	4.868	0.00320	0.00509
F9	30	175.351	4.868	0.00362	0.00575
F10	55	158.859	4.922	0.00465	0.00739
F11	140	122.891	5.330	0.01135	0.01805
F12	78	168.242	4.944	0.00426	0.00678
F13	25	265.317	4.436	0.00088	0.00140
F14	39	212.380	4.458	0.00153	0.00242
F15	117	216.339	5.233	0.00343	0.00545
F16	32	190.606	4.629	0.00234	0.00371
F17	30	174.746	4.623	0.00277	0.00440
F18	45	163.464	5.788	0.01066	0.01696
F19	42	224.732	5.736	0.00520	0.00827
F20	28	217.662	5.540	0.00462	0.00734
F21	28	220.173	5.183	0.00313	0.00497
F22	47	231.025	5.277	0.00309	0.00491
F23	32	232.361	5.654	0.00445	0.00708
F24	51	244.908	5.081	0.00219	0.00348
F25	31	264.518	5.608	0.00311	0.00495
F26	76	250.588	6.045	0.00539	0.00856
F27	47	289.607	5.835	0.00307	0.00488
F28	60	249.641	5.936	0.00491	0.00781
F29	70	266.525	6.007	0.00447	0.00710
F30	38	297.601	5.717	0.00255	0.00405
F31	477	293.834	6.751	0.00660	0.01050
F32	91	278.291	5.874	0.00353	0.00562
F33	70	212.717	5.798	0.00625	0.00994
F34	58	212.942	5.739	0.00589	0.00937
F35	45	262.893	5.660	0.00333	0.00529
F36	25	256.840	5.409	0.00275	0.00436
F37	26	206.054	4.917	0.00273	0.00433
F38	75	256.393	4.853	0.00154	0.00244
F39	75	156.850	5.029	0.00535	0.00850
F40	86	240.606	4.950	0.00199	0.00316
F41	87	230.217	5.593	0.00428	0.00681

Table B3.

PGA values for seismic sources for district headquarter Korba.

Fault No.	Fault length (Li) in km	Hypo-central distance (R) in km	Magnitude M100 [recurrence period—100 Years]	PGA(g)
				50 percentile	84 percentile
F1	51	127.196	4.659	0.00520	0.00827
F2	26	118.412	4.071	0.00295	0.00469
F3	25	254.206	5.508	0.00311	0.00495
F4	39	143.978	4.463	0.00334	0.00531
F5	117	169.597	5.247	0.00579	0.00921
F6	32	162.409	4.634	0.00324	0.00515
F7	30	176.246	4.629	0.00274	0.00436
F8	45	176.181	6.052	0.01178	0.01874
F9	30	109.015	6.709	0.04929	0.07846
F10	30	124.640	4.888	0.00694	0.01104
F11	55	142.431	4.936	0.00578	0.00920
F12	78	170.995	4.594	0.00280	0.00445
F13	77	98.240	4.952	0.01096	0.01745
F14	28	88.029	4.447	0.00736	0.01172
F15	62	81.035	4.759	0.01186	0.01888
F16	46	94.427	4.746	0.00930	0.01480
F17	140	138.092	5.350	0.00945	0.01504
F18	42	237.152	6.016	0.00598	0.00952
F19	28	266.059	5.816	0.00375	0.00597
F20	47	287.334	5.340	0.00192	0.00306
F21	28	273.686	5.242	0.00197	0.00314
F22	75	136.807	5.043	0.00697	0.01109
F23	26	174.579	4.947	0.00397	0.00632
F24	75	222.346	4.858	0.00216	0.00343
F25	86	193.947	4.960	0.00325	0.00517
F26	87	133.076	5.654	0.01368	0.02176
F27	47	278.875	4.562	0.00090	0.00143

Table B4.

PGA values for seismic sources for district headquarter Jashpurnagar.