International Journal of Geosciences, 2012, 3, 179-191
http://dx.doi.org/10.4236/ijg.2012.31020 Published Online February 2012 (http://www.SciRP.org/journal/ijg)
Attenuation of P, S and Coda Waves in the
NW-Himalayas, India
Imtiyaz A. Parvez, Preeti Yadav, K. Nagaraj
CSIR Centre for Mathematcial Modelling and Computer Simulation (C-MMACS) NAL,
Belur Campus, Bangalore, India
Received August 5, 2011; revised September 19, 2011; accepted November 15, 2011
ABSTRACT
The frequency-dependent characteristics of P- and S-wave attenuation in the upper crust of NW Himalayas have been
estimated using local earthquakes for a frequency range of 1.5 to 18 Hz. A total of 43 local events of magnitude 2.1 -
4.8, mostly from the vicinity of Main Boundary Thrust (MBT) and Main Central Thrust (MCT) have been used in the
analysis. The extended coda normalization methods were applied to estimate the quality factors for P-waves (QP) and
S-waves (QS) and the single back-scattering model has been used earlier (Kumar et al. [1]) to determine the quality fac-
tor for coda waves (QC). The observed quality factors QP and QS is strongly frequency dependent and the estimated av-
erage frequency dependent relation is given by QP = (97 ± 3)f (1.06±0.06) and QS = (127 ± 6)f (0.96±0.06) respectively for P-
and S-waves. A comparison of QS estimated in this study and QC previously reported shows that QC > QS for entire fre-
quency range. This indicates the enrichment of coda waves and the importance of scattering attenuation to the attenua-
tion of S-waves in the study region infested with faults and fractures. The ratio QS/QP is found to be greater than unity
for the entire frequency range indicating that the body waves from source to station paths crossed a crustal volume with
dry and rigid rocks. The frequency dependent relations developed in this study can be very useful to ground motion
modeling which in turn is required in the seismic hazard assessment of the region.
Keywords: Attenuation; Quality Factor; Frequency Dependence; NW Himalayas
1. Introduction
In order to investigate the structure of the interior of the
earth and to quantitatively predict the strong earthquake
ground motion in engineering seismology, the informa-
tion on seismic wave attenuation plays an important role.
Especially, the information on high frequency wave at-
tenuation in the lithosphere is of particular importance.
Attenuation parameter Q–1 is an important factor for un-
derstanding the physical mechanism of seismic wave
atenuation in relation to the composition and physical
condition of the earth’s interior [2]. From the engineering
point of view, attenuation of S-waves has been well
studied in various regions in the world as compared with
that of P-waves. Aki [3] first obtained frequency de-
pendent S in Kanto, Japan for the frequency range of
1.5 - 24 Hz by means of the coda-normalization method.
Nevertheless, the information on
1
Q
1
P
Q is also indispen-
sable for evaluating the strong vertical ground motion pre-
cisely in view of the earthquake-resistant design of recent
huge constructions.
Attenuation of seismic waves with frequency strongly
depends on the physical conditions of the underground
crustal media and is caused by different factors like geo-
metrical spreading, scattering, multipathing and anelas-
ticity. The crustal value of attenuation, described as the
inverse of the quality factor (Q–1), shows a close relation
with seismic activity and is given Knopoff [4].
12πQEE  (1)
where ΔE is the energy lost per cycle and E is the total
energy of a harmonic wave. Q expresses the decay of
wave amplitude during its propagation in the medium. It
has been observed that at high frequency (>1 Hz) Q in-
creases with frequency [5] and can be represented by a
power law,

00
n
QQff
1
P
(2)
where f is frequency, Q0 is value of Q at frequency f0 (1
Hz) and n is the frequency dependent coefficient to be
determined from the observations.
The attenuation of seismic waves has been widely
studied in several seismogenic zones using various ap-
proaches (e.g., [6-9]). It has been found that the attenua-
tion for P-wave (Q

) is different from that of S-wave
(S
Q1

). The ratio QS/QP also varies from one region to
another [10]. The coda normalization method to estimate the
C
opyright © 2012 SciRes. IJG

I. A. PARVEZ ET AL. 180
frequency-dependent relation for QS is proposed by [3].
Reference [11] extended this method for simultaneous
measurement of QP and QS. Similarly, high frequency
coda waves recorded during the occurrence of local
earthquakes, which arrive at station after the arrival of all
direct phases, are assumed to be the superposition of back-
scattered primary S-waves generated by the numerous
heterogeneities distributed randomly in the earth’s crust
and upper mantle. These waves arrive at the station on
different time intervals and form a coda. Therefore, the
decay of these waves with time, in a seismogram, pro-
vides the average attenuation characteristics of the me-
dium instead of the property of a single path connecting
from a source to the station. As these waves are the result
of numerous heterogeneities distributed randomly, they
cannot be explained by any deterministic approach in
which a number of parameters are required to describe a
small portion of seismogram. However, they can be
solved by applying the statistical method in which a
small number of parameters is sufficient to describe the
properties of coda waves. [6] and [7] are pioneers in this
field and they proposed a single backscattering model to
use the coda waves of local earthquakes for the estimation
of quality factor (QC) of coda waves in a region. Numer-
ous studies have been carried out in different parts of the
world to determine the seismic wave attenuation proper-
ties of the medium. These studies analyze the coda waves
of local earthquakes for the estimation of QC values, using
the single backscattering model (e.g., [1,12-17]). The main
objective of this study is to understand the attenuation
characteristics of the North-West Himalaya region using
different parts of the seismograms including coda waves
and body waves. For this purpose, the extended coda
normalization method [11] has been used to estimate the
frequency-dependent relationships for QP and QS in the
NW Himalaya region and that is the first estimate of this
kind for this region. The QC estimates for the NW Hima-
laya region have been previously obtained by [1] using
the single back-scattering model of [7] and in the present
study we integrate and compare the estimated QP and QS
with QC obtained by [1].
2. Tectonic Setup of the Region
The Himalaya is the youngest mountains range and is
developed by the continent-continent collision between
Indian and Tibetan plate [18,19]. High levels of tectonic
activity are due to the opposite convergence movements
of north dipping Indian plate under Eurasian plate. The
region is characterized by the presence of many tectonic
features that includes Indian Tsangpo-Suture zone (ISZ),
Main Central Thrust (MCT), Main Boundary Thrust
(MBT) and Himalayan Frontal Thrust (HFT). The two
thrusts exist through the entire length of the Himalaya.
The MBT separates the lesser Himalaya from the sub-
Himalaya belt while MCT separates the high Himalaya
from the lesser Himalaya. In the present study region,
along with MCT, MBT and HFT the Jawalamukhi thrust
(JMT), Drang thrust, Panjal thrust, Vakirata thrust, Sun-
dernagar fault, Kistwar fault and Ropar fault are well
known tectonic features. The tectonic movement of NW
Himalayas and major discontinuities are shown in Figure
1. Reference [1] has explained in detail the tectonic setup
of the region.
3. Method of Analysis
The coda normalization method [2] is based on the
empirical observation that the coda spectral amplitude at
lapse times greater than twice the S-wave travel time is
proportional to the source spectral amplitude of the S-
waves at distances of less than 100 km. This implies that
the coda spectral amplitude is not dependent to the hypo
central distance and that the site and source terms which
are common in coda and direct waves can be removed by
the coda normalization method [3].
Reference [11] has extended the above method for the
estimation of Q under the assumption that the earth-
quakes within a magnitude range have the same spectral
ratio of P- to S-wave radiation within a narrow frequency
range. This assumption holds well even if the spectral
shapes of P- and S-waves are different (e.g., [10,20]).
Therefore, we can write

  
cc SP
,
A
ftS fSf (3)


Sf
P and

where,

Sf


S are the source spectral am-
plitude of P- and S-waves. Using the above assumption,
an equation for estimating QP can be written as [33]:
 
P
CPP
,π
ln const
,crr
Afrrfrf
Aft QfV



 





(4)
 
S
CcS S
,π
ln const
,rr
Afrrfrf
Aft QfV



 


 (5)


,
P


,
S
fr and
A
A
where fr
V


are the direct P- and
S-waves maximum amplitudes at the hypocentral dis-
tance r (km), respectively. P and S V are the average
P- and S-wave velocities. The quality factor for P-wave
can be obtained from the linear regression of
P
C
,
ln ,crr
Afrr
Aft







versus r by means of the least squ-
are method and same is used for S-waves.
4. Data
The study area covered comprises of three seismic sta-
tions Pathankot (PTK), Hoshiarpur (HOS) and Amritsar

I. A. PARVEZ ET AL. 181
Figure 1. General Seismotectonic and topographical map of NW Himalayas and adjoining area. MCT: Main Central Thrust;
MBT: Main Boundary Thrust; HFT: Himalayan Frontal Thrust; JMT: Jawalamukhi Thrust; KWF: Kisatwar Fault; SNF:
Sundarnager Fault; eart hquake e picentre s are plotted by circle s, triangles r epresent the r ecording stations (PTK: P athankot;
HOS: Hoshiarpur; ASR: Amritsar) and cities are shown by squares.
(ASR) in NW Himalaya region (Figure 1). The first
seismic station, PTK is on the top of the Siwalik Hills;
the second one, HOS is at Siwalik foothills; while third
one, ASR station is located on the Gangetic plain. The
station PTK is situated on hard bedrock in the vicinity of
high tectonic and seismic activity at high altitude. The
station HOS is situated at alluvium near recent tectonic
and moderate seismic activity, and the station ASR is on
a thick alluvium of the Gangetic plain away from tectonic
and seismic activities. All the stations were equipped with
portable high quality three component short-period (1 Hz
natural frequency) L4-3D seismometers of Mark pro-
ducts (USA) and high dynamic range 24 bit recording
apparatus of REFTEK (USA). The instruments were set-
up to digitize the signal at 100 sps and an antiallising
filter was applied to get the flat velocity spectrum be-
tween 1 and 40 Hz. The digital events data utilized for Q
calculation were recorded during 1997-1999 at the regional
seismograph network of three seismic stations by
Earthquake Research Centre, Guru Nanak Dev University,
Amritsar. During the given period, more than 300 seismic
events were recorded from different epicentral ranges.
Out of these, 36 local events were used by [1] for coda Q
calculation and the same has been used in this study for
estimating QP and QS.
The detailed epicentral information of seismic events
is listed in Table 1, which indicates that the maximum
events are recorded at PTK station while minimum events

I. A. PARVEZ ET AL. 182
Table 1. Earthquake data used for QP and QS calculation.
Sr.
No.
Date
(dd/mm/yy)
O.Time
(hh:mm:ss)
Latitude
(˚N)
Longitude
(˚E)
∆
(km)
Depth
(km) M
Station: Pathankot
1 23/12/97 04:15:04.90 33.805 75.234 161 33.0 4.0
2 25/04/98 18:15:50.80 31.533 76.028 108 30.0 2.3
3 18/05/98 12:29:31.80 33.157 75.839 102 65.0 3.5
4 01/07/98 22:50:51.40 32.691 75.318 53 19.5 3.5
5 05/07/98 22:33:36.70 32.852 75.675 55 10.0 2.4
6 05/07/98 23:04:21.80 32.837 75.596 47 12.0 3.0
7 06/07/98 10:24:08.80 32.987 75.629 102 82.5 4.2
8 31/07/98 02:16:14.50 32.522 75.372 37 6.0 3.6
9 17/08/98 17:55:00.80 33.223 76.001 95 33.0 3.4
10 25/08/98 11:48:04.90 32.543 76.533 75 15.0 2.6
11 02/09/98 01:02:26.10 32.957 76.342 79 5.0 3.0
12 28/09/98 00:21:02.60 32.737 75.947 40 15.0 3.1
13 28/09/98 21:17:01.00 31.551 76.995 154 22.0 2.2
14 17/10/98 09:24:45.00 32.217 76.545 85 33.0 4.5
15 06/11/98 14:29:34.50 32.299 76.010 44 34.0 3.8
16 11/01/99 01:30:26.10 31.820 77.115 146 5.0 3.5
17 16/01/99 03:07:46.80 32.987 76.058 66 5.0 2.7
18 15/02/99 00:14:52.00 32.232 76.523 76 4.0 2.7
19 21/02/99 15:14:56.50 32.833 75.898 46 10.0 2.1
20 15/03/99 21:56:37.50 33.062 76.078 75 5.0 2.5
21 16/03/99 19:16:19.20 32.396 76.732 93 15.0 2.3
22 22/03/99 20:31:17.70 32.894 75.813 50 5.0 2.2
23 27/03/99 11:49:31.40 32.462 76.422 63 10.0 3.5
24 22/04/99 05:22:04.80 32.996 75.768 61 7.0 3.2
25 07/05/99 14:44:57.40 31.861 75.455 70 33.0 3.0
26 08/05/99 20:59:17.40 33.442 75.912 112 15.0 2.7
27 12/07/99 21:45:59.40 33.110 75.768 102 72.0 3.7
28 27/07/99 20:19:09.70 32.577 76.466 68 10.0 3.2
29 28/07/99 10:42:52.70 32.533 76.313 53 10.0 2.5
30 30/07/99 18:18:25.20 32.704 76.633 88 15.0 2.5
31 31/07/99 13:02:25.80 33.046 76.777 116 15.0 2.2
Station: Amritsar
32 29/07/97 09:43:35.80 32.831 73.680 171 10.0 4.8
33 29/07/97 18:00:18.20 31.554 76.817 189 33.0 4.7
34 13/08/97 23:10:15.10 31.211 76.694 184 33.0 4.2
35 21/02/98 19:08:04.30 33.292 75.466 193 15.0 2.6
36 24/03/98 04:25:42.90 32.462 73.901 126 42.5 4.0
37 01/07/98 22:50:51.40 32.691 75.318 126 19.5 3.5
38 05/07/98 23:04:21.80 32.837 75.596 152 12.0 3.0
39 28/09/98 21:17:01.10 31.551 76.995 202 30.0 2.2
40 17/10/98 09:24:45.00 32.217 76.545 175 33.0 4.5
Station: Hoshiarpur
41 05/07/98 23:04:30.00 32.837 75.600 115 12.0 3.0
42 17/10/98 09:24:45.00 32.217 76.550 98.2 4.5 4.5
43 06/11/98 14:29:34.50 32.299 76.010 95.4 34.0 3.8

I. A. PARVEZ ET AL. 183
at HOS station. All the 31 events of PTK station used
here are from 25 ≤ R ≤ 165 km of epicentral distance, all
nine events of ASR station used are from 100 ≤ R ≤ 205
km of epicentral distance and in case of HOS station total
three events taken are from 50 ≤ R ≤ 115 km epicenter
range. Most of the seismic events are located between
MBT and MCT bounded by two other transverse faults
as the Sundernagar fault to the east and of same trend the
Kistwar fault to the west. This region is very close to the
PTK station in the northeast direction.
5. Results and Discussion
The seismograms have been filtered using Butterworth
band pass filter with six frequency pass bands of 0.5 - 1.5
Hz, 1 - 3 Hz, 2 - 5 Hz, 5 - 10 Hz, 10 - 15 Hz and 12 - 24
Hz. On the filtered seismograms, maximum amplitudes
of direct P- and S-waves were measured from vertical
and horizontal component respectively. The coda spectral
amplitude, Ac(f, tc), has been measured for each fre-
quency band by choosing to be longer than twice the S-
wave travel time. The average velocities of 6.1 km/sec
and 3.5 km/sec for P- and S-waves, respectively, have
been used in the present study [1]. We also assume the
geometrical spreading is proportional to r–1. The plots of
the quantity ln((Ap/Ac)r) and ln((As/Ac)r) versus r along
with the least square fitted lines for the station PTK are
shown in Figure 2. The corresponding plots of the other
two stations ASR and HOS are shown in Figures 3 and 4
respectively. The slopes of the best fitted lines are used
to estimate QP and QS using the Equations (4) and (5)
respectively for six different frequency bands. The mean
values of QP and QS, thus, obtained at different frequency
bands and their average values for the three stations, are
given in Table 2. We note that the estimated Q values
increase with the increase in frequency.
The value of QP for PTK Station varies from 94 at (0.5
- 1.5) Hz to 1893 at (12 - 24) Hz, for ASR Station QP
varies from 68 at (0.5 - 1.5) Hz to 1783 at (12 - 24) Hz
and for HOS Station it varies from 71 at (0.5 - 1.5) Hz to
1656 at (12 - 24) Hz. Similarly, the value of QS for PTK
Station varies from 168 at (0.5 - 1.5) Hz to 2694 at (12 -
24) Hz, for ASR Station, the range is from 122 at (0.5 -
1.5) Hz to 2155 at (12 - 24) Hz and for HOS Station, it
varies from 115 at (0.5 - 1.5) Hz to 2245 at (12 - 24) Hz.
The average value for the region is also estimated and it
varies from 78 at (0.5 - 1.5) Hz to 1777 at (12 - 24) Hz
for QP and for QS, the values are 135 at (0.5 - 1.5) Hz to
2365 at (12 - 24) Hz.
We find a clear frequency dependency of QP and QS as
they increase with frequency and that indicates the fre-
quency-dependent nature of Q estimates in the region.
Their frequency dependencies indicate that the at-
tenuation of P- and S-waves at high frequencies is less
pronounced than at lower frequencies. This is a charac-
teristic of tectonically active zones with complex struc-
ture. In order to estimate the frequency-dependent rela-
tions for Q, the power law Q = Q0 f n is fitted to the esti-
mated Q values for each station. We have plotted log QP
and log QS with the log of frequency to estimate the fre-
quency-dependent relationships as shown in Figure 5.
The frequency-dependent relations thus obtained for all
the three stations, along with the average, are given in Ta-
ble 3. The average frequency-dependent relations for the
region are QP = (97 ± 3) f (1.06 ± 0.06) and QS = (127 ± 6) f
(0.96±0.06).
We have estimated QC earlier for NW-Himalayas [1]
Table 2. QP and QS values obtained for the three stations and their average values for six different frequency bands.
ASR HOS PTK Average
Sl. No. Freq. band
(Hz) QP Q
S Q P Q S Q P Q S Q P Q S
1 0.5 - 1.5 68 122 71 115 94 168 78 135
2 1 - 3 132 409 126 245 261 288 173 314
3 2 - 5 323 551 314 495 653 919 430 655
4 5 - 10 647 1124 712 998 884 1421 748 1181
5 10 - 15 1075 1764 1013 1492 1508 1727 1199 1661
6 12 - 24 1783 2155 1656 2245 1893 2694 1777 2365
Table 3. Frequency-dependent relationships of QP and QS obtained for the three stations and overall average value for the
region.
Frequency-dependent relationships for three stations
Sl. No. Station Code Relation for P wave Relation for S wave QS/QP ratio
1 ASR QP = (98 ± 4) f (1.11 ± 0.04) Q
S = (119 ± 7) f (0.94±0.07) 1.21
2 HOS QP = (85 ± 3) f (1.1 ± 0.06) Q
S = (122 ± 3)f (1.01±0.03) 1.43
3 PTK QP = (103 ± 8) f (0.99 ± 0.09) Q
S = (139 ± 13)f (0.95±0.09) 1.35
4 Average QP = (97 ± 3) f (1.06 ± 0.06) Q
S = (127 ± 6)f (0.96±0.06) 1.31

I. A. PARVEZ ET AL. 184
2060100 140 180
r (kms)
1
3
5
7
9
ln((A
P
\A
C
) r)
5-10Hz
Q
P
=884
2060100 140 180
r (kms)
1
3
5
7
9
ln((A
P
\A
C
) r)
2-5Hz
Q
P
=653
2060100 140 180
r (kms)
1
3
5
7
9
ln((A
P
\A
C
) r)
1-3Hz
Q
P
=261
2060100
r (kms)
140 180
3
5
7
9
11
ln((A
S
\A
C
) r)
5-
Q
10Hz
S
=1421
2060100
r (kms)
140 180
3
5
7
9
11
ln((A
S
\A
C
) r)
1-3Hz
Q
S
=288
2060100 140 180
r (kms)
1
3
5
7
9
ln((A
P
\A
C
) r)
10-15Hz
Q
P
=1508
2060100
r (kms)
140 180
3
5
7
9
11
ln((A
S
\A
C
) r)
0.5-1.5 Hz
S
=168 Q
2060100
r (kms)
140 180
3
5
7
9
11
ln((A
S
\A
C
) r)
2-5Hz
Q
S
=919
2060100
r (kms)
140 180
3
5
7
9
11
ln((A
S
\A
C
) r)
10
Q
-15Hz
S
=1727
2060100 140 180
r (kms)
1
3
5
7
9
ln((A
P
\A
C
) r)
0.5-1.5Hz
Q
P
=94
2060100 140 180
r (kms)
1
3
5
7
9
ln((A
P
\A
C
)r)
12-24Hz
Q
P
=1893
2060100
r (kms)
140 180
3
5
7
9
11
ln((A
S
\A
C
)r)
12
Q
-24Hz
S
=2694
Figure 2. Plots of coda normalized peak amplitude decay of P- and S-waves with hypocentral distance for the six frequency
bands along with least-square be st fitte d line for P TK station.

I. A. PARVEZ ET AL. 185
100 120 140 160 180 200 220
r (kms)
2
4
6
8
10
ln((A
P
\A
C
) r)
0.5-1.5Hz
Q
P
=68
100 120 140 160 1
r (kms)
80 200 220
3
5
7
9
11
ln((A
S
\A
C
) r)
0.5-1.5Hz
S
=122 Q
100 120 140 160 180 200 220
r (kms)
2
4
6
8
10
ln((A
P
\A
C
) r)
1-3Hz
Q
P
=132
100 120 140 160 1
r (kms)
80 200 220
3
5
7
9
11
ln((A
S
\A
C
) r)
1-3Hz
Q
S
=409
100 120 140 160 180 200 220
r (kms)
2
4
6
8
10
ln((A
P
\A
C
) r)
2-5Hz
Q
P
=323
100 120 140 160 1
r (kms)
80 200 220
3
5
7
9
11
ln((A
S
\A
C
) r)
2-5Hz
Q
S
=551
100 120 140 160 180 200 220
r (kms)
2
4
6
8
10
ln((A
P
\A
C
) r)
5-10Hz
Q
P
=647
100 120 140 160 1
r (kms)
80 200 220
3
5
7
9
11
ln((A
S
\A
C
) r)
5-10Hz
S
=1124 Q
100 120 140 160 180 200 220
r (kms)
2
4
6
8
10
ln((A
P
\A
C
) r)
10-15Hz
Q
P
=1075
100 120 140 160 1
r (kms)
80 200 220
3
5
7
9
11
ln((A
S
\A
C
) r)
10-15Hz
S
=1764 Q
100 120 140 160
r (kms)
180 200 220
3
5
7
9
11
ln(A
S
\A
C
)r)
12-24Hz
S
=2155 Q
100 120 140 160 180 200 220
r (kms)
2
4
6
8
10
ln((A
P
\A
C
)r)
12-24Hz
Q
P
=1783
Figure 3. Plots of coda normalized peak amplitude decay of P- and S-waves with hypocentral distance for the six frequency
bands along with least-square be st fitte d line for ASR station.

I. A. PARVEZ ET AL. 186
9095100105 110 115 120
r (kms)
3
4
5
6
ln((A
P
\A
C
) r)
1-3Hz
Q
P
=126
9095100 105
r (kms)
110 115 120
5
6
7
8
9
ln((A
S
\A
C
) r)
1-3Hz
Q
S
=245
9095100105 110 115 120
r (kms)
3
4
5
6
7
ln((A
P
\A
C
) r)
2-5Hz
Q
P
=314
9095100 105
r (kms)
110 115 120
5
6
7
8
9
ln((A
S
\A
C
) r)
2-5Hz
Q
S
=495
9095100105 110 115 120
r (kms)
4
5
6
7
ln((A
P
\A
C
) r
)
5-10Hz
Q
P
=712
9095100105 110 115 120
r (kms)
4
5
6
7
ln((A
P
\A
C
) r)
10-15Hz
Q
P
=1013
9095100 105
r (kms)
110 115 120
5
6
7
8
9
ln((A
S
\A
C
) r)
10-15Hz
Q
S
=1492
9095100 105
r (kms)
110 115 120
5
6
7
8
9
ln((A
S
\A
C
) r)
5-10Hz
Q
S
=998
9095100105 110 115 120
r (kms)
3
4
5
6
ln((A
P
\A
C
) r)
0.5-1.5Hz
Q
P
=71
9095100 105
r(kms)
110 115 120
4
5
6
7
8
ln((A
S
\A
C
) r)
0.
Q
5-1.5Hz
S
=115
9095100105 110 115 120
r (kms)
4
5
6
7
ln((A
P
\A
C
)r)
12-24Hz
Q
P
=1546
9095100 105
r (kms)
110 115 120
5
6
7
8
9
ln((A
S
\A
C
)r)
12-24Hz
Q
S
=2245
Figure 4. Plots of coda normalized peak amplitude decay of P- and S-waves with hypocentral distance for the six frequency
bands along with least-square be st fitte d line for HOS station.

I. A. PARVEZ ET AL. 187
-0.400.4 0.8 1.2 1.6
log f
1.6
2
2.4
2.8
3.2
3.6
log
Q
QP = (98 ± 4) f (1.11 ± 0.04)
-0.400.4 0.8
log f
1.2 1.6
2
2.4
2.8
3.2
3.6
log
Q
QS = (119 ± 7) f (0.94±0.07)
-0.400.4 0.8 1.2 1.6
log f
1.6
2
2.4
2.8
3.2
3.6
log
Q
QP = (85 ± 3) f (1.1 ± 0.06)
-0.400.4 0.8
log f
1.2 1.6
2
2.4
2.8
3.2
3.6
log
Q
QS = (122 ± 3) f (1.01±0.03)
-0.400.4 0.8 1.2 1.6
log f
1.6
2
2.4
2.8
3.2
3.6
log
Q
QP = (103 ± 8) f
(0.99 ± 0.09)
-0.400.4 0.8
log f
1.2 1.6
2
2.4
2.8
3.2
3.6
log
Q
QS = (139 ±
ASR
PTK PTK
HOS HOS
ASR
13) f (0.95±0.09)
-0.400.4 0.8 1.2 1.6
log f
1.6
2
2.4
2.8
3.2
3.6
log
Q
QP =(97 ± 3) f (1.06 ± 0.06)
-0.400.4 0.8
log f
1.2 1.6
1.6
2
2.4
2.8
3.2
3.6
log
Q
QS = (127 ±
Average Average
6) f (0.96±0.06)
Figure 5. Frequency-dependent relationships for the three stations ASR, HOS and PTK respectively, along with average of
all the three stations.

I. A. PARVEZ ET AL.
IJG
188
1.8
2.2
2.6
3
3.4
3.8
log
Q
using the back-scattering model [7] and we have found
QC = 158 f1.05 for the NW Himalaya region. It has been
found by [6] and [7] that the coda waves are determined
by S to S-backscattered waves and have common ampli-
tude decay (e.g., Rautian et al., [10]). On the other hand
Zeng et al. model [21] predicts that the effects of intrinsic
and scattering attenuation combine in a manner such that
QC should be more than QS.
We compared QC, QP and QS for this region and the es-
timated average Q values as a function of frequency is
shown in Figure 6. One can see from this figure that QC
is always greater than QS and QP for all the frequency
ranges that indicate possible high frequency coda en-
richment. This may also be due to scattering attenuation
in the upper lithosphere which is highly heterogeneous.
The high frequency coda enrichment has also been re-
ported from other regions (e.g., [22,23]). Such observa-
tion may be further investigated using the multiple scat-
tering models [24].
Figure 6 also shows that the ratio Q
S/QP is always
greater than 1 for entire frequency range and is closed to
1 at high frequency. It has been found from the labora-
tory measurements that QS/QP ratio is less than unity in
fluid saturated rock matrices and larger than unity in dry
rocks (e.g., [25-27]). Vassiliou et al., [28] also found that
the QS/QP ratio to be unity for air dry rocks and less than
unity for fully saturated rocks. The study of Johnston et
al., [29] also indicates that at surface pressure most dry
rocks have QS/QP > 1. Our result on QS/QP ratio is in the
range of 1.21 - 1.43 (Table 3) and is well in agreement
with the results obtained by the laboratory measurement
and other experimental results mentioned above. If we see
QS/QP ratio for individual stations, Amritsar (ASR) has
the least 1.21 compared to the other two stations HOS
and PTK closed to Himalayas and Himalayan foothills.
We found the similar situation with QC values also [1].
Such difference in attenuation properties is due to real
crustal differences and may be the scatters in the region
have different patterns. The ratio QS/QP as well as the
frequency dependence of quality factors estimated in this
study indicates that the scattering is an important factor
contributing to the attenuation of body waves in the re-
gion. The QS/QP ratio having values larger than unity
also indicates that the body waves from source to station
paths crossed a crustal volume having dry and rigid
rocks.
The QP and QS values obtained in the present study
have been compared with those estimated for other tec-
tonic and seismically active different regions of the world
in Figures 7(a) & (b). We observe from the Figure 7(a)
that the rate of increase of Q(f) for P-wave in the NW
Himalaya region is similar with those of other regions
like the Kachchh, Saurastra and Mainland region of Gu-
jarat, India. They also compare very well with other re-
Q
P
= 97 f
1.06
Q
S
= 127 f
0.96
Q
C
= 158 f
1.05
-0.20.2 0.611.4 1.8
log f
Figure 6. Estimated average Q values as a function of fre-
quency for P, S, and coda waves, and the corresponding
fitting of power law.
gions like Baltic Shield and South Eastern Korea. How-
ever, they differ in absolute values from the regions like
Koyna, Chamoli, Kanto region of Japan and Central South
Korea. A similar comparison is shown in Figure 7(b) for
QS of NW-Himalaya region with other regions of the
world and this also show the similar trend of the rate of
increase of Q(f) for S-wave. If we compare with other re-
gions of the world, except for the Saurastra, all the other
regions are very well compared with the present study.
The QS of Saurastra region at low frequency is well com-
parable, however at high frequency it is high compared
to the other region. Such variation may also be due to
different geology and tectonics, as most of the Saurastra
region is covered by Deccan basalt which is compact and
rigid and that is more sensitive to frequency.
6. Conclusions
This study is an attempt to understand the attenuation of
P-, S- and Coda-waves in the NW-Himalayas of the India
using the different parts of the seismograms. The fre-
quency-dependent estimates of body waves (QP and Qs)
have been obtained using the extended coda normalize-
tion method, and the single back-scattering model has
been used to determine the relation for coda waves. The
obtained relations are QP = (97 ± 3) f (1.06 ± 0.06) and QS =
(127 ± 6) f (0.96±0.06) and show strong dependency on fre-
quency. The frequency dependent QP, QS and QC indi-
cates that the seismic energy of high frequency waves is
attenuated more in the upper lithosphere than in the
lower lithosphere. We also found that QP and QS of NW
Himalaya is comparable to the other seismic active re-
gion of the world like Kachchh, Saurastra and Mainland
region of Gujarat, India, Baltic Shield and South Eastern

I. A. PARVEZ ET AL. 189
1 10
f (Hz)
100
10
100
1000
10000
Q
P
Cham oli
Kachchh
Koyna
Mainland
Saurastra
Baltic Shield
Central South Korea
Kanto, Japan
South Eastern Korea
Present Study
(a)
1 10
f (Hz)
100
10
100
1000
10000
Q
S
Chamoli
Kachchh
Koyna
Mainland
Saurastra
Baltic Shield
Central South Korea
Kanto, Japan
South Eastern Korea
Present Study
(b)
Figure 7. (a) Comparison of Q(f) for P-waves of the NW Himalaya region obtained in this study (Q(f) = 97 f 1.06) with those of
other regions of the world (dashed lines) and India (solid lines). Line 1: Chamoli, Himalaya, Q(f) = 44 f 0.82 [30]; Line 2:
Kachchh region, Gujarat, Q(f) = 105 f 0.82 [31]; Line 3: Koyna region, Q(f) = 59 f 1.04 [32]; Line 4: Mainland region, Gujarat,
Q(f) = 163 f 0.77, [31]; Line 5: Saurastra region, Gujarat, Q(f) = 148 f 0.92, [31]; Line 6: Baltic Shield, Q(f) = 125 f 0.89, [33]; Line
7: Central South Korea, Q(f) = 333 f 0.54, [34]; Line 8: Kanto, Japan, Q(f) = 32 f 0.95 [11]; Line 9: South Eastern Korea, Q(f) =
111 f 1.05 [35]; (b) Comparison of Q(f) for S-waves of the NW Himalaya region obtained in this study (solid line, Q(f) = 127 f
0.96 )with those of other regions of the world (dashed lines) and India (solid lines). Line 1: Chamoli, Himalaya, Q(f) = 87 f 0.71 ,
[30]; Line 2: Kachchh region, Gujarat, Q(f) = 74 f 1.06, [31]; Line 3: Koyna region, Q(f) = 71 f 1.32, [32]; Line 4: Mainland re-
gion, Gujarat, Q(f) = 118 f 0.65, [31]; Line 5: Saurastra region, Gujarat, Q(f) = 149 f 1.43, [31]; Line 6: Baltic Shield, Q(f) = 125 f
1.08, [33]; Line 7: Central South Korea, Q(f) = 333 f 0.42, [34]; Line 8: Kanto, Japan, Q(f) = 83 f 0.73, [11]; Line 9: South Eastern
Korea, Q(f) = 250 f 1.08, [35].
Korea. However, they differ in absolute values from the
regions like Koyna, Chamoli, Kanto region of Japan and
Central South Korea. The ratio QS/QP is found to be
greater than one in the present analysis, which is in agree-
ment with the laboratory measurements and other studies
reported in the literature. This also indicates that scatter-
ing is an important factor contributing to the attenuation
of body waves in the region. A comparison of QC ob-

I. A. PARVEZ ET AL. 190
tained by [1] and QS obtained in the present study show
that QS < QC for all the frequency ranges reflecting the
enrichment of coda waves which suggests the importance
of scattering attenuation to the attenuation of S waves in
the region. The attenuation parameters obtained in this
study are useful for the estimation of source parameters
and simulation of earthquake ground motions in the re-
gion which is needed to assess the seismic hazard in the
region of NW Himalaya, India.
7. Acknowledgements
The authors are thankful to Naresh Kumar and H. S. Virk
for providing the micro-earthquake data. We are also
thankful to SIC, C-MMACS for his permission and to
provide the facilities to complete this work. We also thank
the Department of Science and Technology, Government
of India to provide the fellowship to Preeti under DST
project R-0-156.
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