Strong-motion amplitudes in Himalayas and a pilot study for the deterministic first-order microzonation in a part of Delhi city
IR@C-MMACS: CSIR-Centre for Mathematical Modelling and Computer Simulation, Bangalore
View Archive Info| Field | Value | |
| Title |
Strong-motion amplitudes in Himalayas and a
pilot study for the deterministic first-order
microzonation in a part of Delhi city
|
|
| Creator |
Parvez, Imtiyaz A
|
|
| Subject |
Computational Seismology
|
|
| Description |
The interdependence among the strong-motion amplitude,
earthquake magnitude and hypocentral distance
has been established1 for the Himalayan region
using the data set of six earthquakes, two from the
Western Himalayas (WH) and four from the Eastern
Himalayas (EH) (Mw = 5.2–7.2) recorded by strongmotion
networks in the Himalayas. The level of the
peak strong-motion amplitudes in the EH is threefold
larger than that in the WH, in terms of both
peak acceleration and peak velocities. In the present
study, we include the strong-motion data of Chamoli
earthquake (Mw = 6.5) of 1999 from the western subregion,
to see whether this event supports the regional
effects. New results fit well with our earlier
prediction in WH. The minimum estimates of peak
acceleration (Apeak) for the epicentral zone of
Mw= 7.5–8.5 events is 0.25–0.4g for the WH and
1.0–1.6g for the EH. Similarly, the expected minimum
epicentral values of peak velocity (Vpeak) for
Mw = 8 are 35 cm/s for WH and 112 cm/s for EH,
respectively. The presence of unusually high levels of
epicentral amplitudes for the eastern sub-region also
agrees well with the macroseismic evidence1. Therefore,
these results represent systematic regional effects,
and may be considered as a basis for future
regionalized seismic hazard assessment in the Himalayan
region.
Many metropolitan and big cities of India are situated
in the severe hazard zone just south of the Himalayas.
A detailed microzonation study of these
sprawling urban centres is therefore urgently required
for a better understanding of ground-motion
and site effects. An example of the study of site effects
and microzonation of a part of metropolitan
Delhi is presented based on a detailed modelling
along a NS cross-section from the Inter State Bus
Terminal to Sewanagar. Full synthetic strong-motion
waveforms have been computed using the hybrid
method, a combination of modal summation and finite
difference techniques, for the earthquake source
of 15 July 1720 (MMI = IX, M = 7.4), and mapped all
along the cross-section. The response spectra ratio,
i.e. the response spectra computed from the signals
synthesized along the laterally varying section normalized
by the response spectra computed from the
corresponding signals, synthesized for the bedrock
reference regional model, have been determined as
well.
|
|
| Publisher |
Indian Academy of Sciences.
|
|
| Date |
2002-01-25
|
|
| Type |
Article
PeerReviewed |
|
| Format |
application/pdf
|
|
| Identifier |
http://cir.cmmacs.ernet.in/26/1/curr%2Dsc%2D2002b.pdf
Parvez, Imtiyaz A (2002) Strong-motion amplitudes in Himalayas and a pilot study for the deterministic first-order microzonation in a part of Delhi city. Current Science, 82 (2). pp. 158-166. ISSN 0011-3891 |
|
| Relation |
http://www.ias.ac.in/currsci
http://cir.cmmacs.ernet.in/26/ |
|