Acceleration attenuation regularities in Western Himalaya

O.O. Erteleva1, F.F.Aptikaev1, S.N. Somala2, J.R. Kayal3, M.C. Raghucharan2

1 Schmidt Institute of Physics of the Earth, Russian Academy of Sciences, Moscow, Russia

2 Indian Institute of Technology, Hyderabad, India

3 National Institute of Technology, Agartala, India

Corresponding author: O.O. Erteleva, e-mail: ertel@ifz.ru

Abstract. The first stage of the seismic treatment assessment for earthquake engineering design is seismic hazard assessment. For this purpose during seismological and seismotectonic researches the sesmogeneric structures are selected. Then, the maximal credible magnitudes, the corresponding recurrence periods, the faulting types, the distances between the selected faults and the construction sites, the ground types at the site are investigated. And at last it is necessary to assess the acceleration amplitudes decay – to investigate the attenuation acceleration regularities. In this article various techniques for assessment of acceleration attenuation with distance in the epicentral zones of earthquakes are considered. It’s shown that the empirical estimations of mean values of the amplitudes for various distances yield the highest accuracy. Any a priori given expressions for attenuation curves aren't applied. At the Institute of Physics of the Earth (IPE), Moscow, using the world-wide strong ground motion database, it is shown, that in the engineering range of accelerations, the zones differing with attenuation and dependences on the source mechanism and ground conditions are identified. Each zone has the own attenuation equation with the corresponding standard deviation. Such methodic of acceleration attenuation assessment is applied for Garhwal region, Himalayas Seismic Belt. The near-field strong ground motion records registered in the near fields of the recent strong earthquakes in the western part of the Himalayas. Strong motion records of the 1986 Dharamsala (MW = 5.5), 1991 Uttarkashi (MW = 6.8) and1999 Chamoli (MW = 6.5) earthquakes are used. The attenuation curve for Garhwal is designed. Empirical data are approximated with the developed attenuation equations having rms deviation of about 50% against 100% by a semi-empirical method. The problem of the regional features at the region under investigation is discussed. These results are much useful for seismic hazard / risk evaluation in the Himalayas.

Keywords: peak acceleration, magnitude, distance, source mechanism, ground type, attenuation, strong ground motion, seismotectonics, Western Himalaya, Garhwal

About the authors

ERTELEVA Olga Olegovna – Candidate of Physical and Mathematical Sciences, Leading Researcher, Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences. 123242, Moscow, ul. Bolshaya Gruzinskaya, 10, building 1. E-mail: ertel@ifz.ru

APTIKAEV Felix Fuadovich – Doctor of Physical and Mathematical Sciences, Professor, Chief Researcher, Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences. 123242, Moscow, ul. Bolshaya Gruzinskaya, 10, building 1. E-mail: felix@ifz.ru

SOMALA Surendra Nadh – Dr., Assistant Professor, Department of Civil Engineering, Indian Institute of Technology Hyderabad. Hyderabad–502285, India. E-mail: surendra@iith.ac.in

KAYAL Jnana Ranjan – Professor, Dr., previously: Geological Survey of India, presently: National Institute of Technology, Agartala. Agartala–799046, India. E-mail: jr.kayal@gmail.com

RAGHUCHARAN Manikya Choudari – Ph.D. Student, Department of Civil Engineering, Indian Institute of Technology, Hyderabad. Hyderabad–502285, India. E-mail: ce15resch11009@iith.ac.in

Cite this article as: Erteleva O.O., Aptikaev F.F., Somala S.N., Kayal J.R., Raghucharan M.C. Acceleration attenuation regularities in Western Himalaya, Voprosy Inzhenernoi Seismologii (Problems of Engineering Seismology). 2019. V.46, No. 2. P. 74–86. [in Russian]. https://doi.org/10.21455/VIS2019.2-7

English translation of the article will be published in Seismic Instruments, ISSN: 0747-9239 (Print) 1934-7871 (Online), https://link.springer.com/journal/11990