seismic history of hyderabad city

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    CHAPTER-III

    SEISMIC HISTORY OF HYDERABAD CITY

    3.1 GENERAL

    SEISMIC HISTORY OF HYDERABAD CITY

    Hyderabad is located in a zone where earthquakes up to 5.0 on the Richter scale can occur.

    But, any seismic activity in the eastern side, which includes Godavari and Badrachalam

    which are located in a zone where earthquakes that measure up to 5. on the scale can occur,

    can a!!ect the city.

    "#e do not e$pect an earthquake in Hyderabad, but earthquakes are a phenomenon that

    cannot be predicted," %ational Geophysical Research institute, &eputy &irector, 'r B (

    Rasto)ii, in an interview with "*he *imes o! +ndia".

    ome o! the ma-or seismic activities in the re)ion are !urnished here under in the table.

    However, !or the !uture plannin) an earth quake ma)nitude o! 5, and in Richter scale are

    considered !or the seismic hazard analysis in the study.

    Historic eart !"a#e e$e%ts i% H&'era(a' cit&

    S No. Year Ma)%it"'e Area

    / /12 2.0 Hyderabad

    3 / 5.00 Hyderabad

    2 /43 2.30 Gandipet

    1 /42 1.00 'edical

    5 30/0 /.0 anasthalipuram

    3.* E+ice%tre a%' Fa",ts

    eismic history o! Hyderabad city

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    *wo ma-or !aults traversin) to words north west direction as shown in satellite interpreted

    map. *hese zones may be considered as seismic hazard zones in Hyderabad. *he epicentre

    distance may be around 10650sq.km

    Fi) 3. sate,,ite a+ o/ H&'era(a' cit&

    3.3 Geo,o)& o/ H&'era(a'

    *he entire district o! Hyderabad is underlain by 7chaean 8rystalline 8omple$, consistin) o!

    pink and )rey )ranites, banded )ranite )neiss9s, mi)matites, pe)matite, quartz ree!s, and

    dolerite dykes. 'assive )ranite and )ranite6)neiss crop out as hills around the city and as

    isolated hills within, and !orm, domed rid)es, scraps, massive blocks and tors. *he )ranites

    are medium to coarse )rained, poryphyritic and equi6)ranular in te$ture and !oliated at

    places. :ink and )rey )ranite constitute, ma-or out crops in the hills.

    eismic history o! Hyderabad city

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    *he northern and eastern hills in the district contain )ranite6)neiss with mi)matitic

    zones. &olerite dykes traverse mostly in east6west and north6south directions and a !ew in

    %%#6;; directions.

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    Group Generalised &escription *ype o! !ractures &irections

    + Aa #%#6;;A1a Collow the course o! *ensional !ractures,

    'usi river and parallel !aults in these direc6

    Ab ;%;6##A1b to the dykes tions due south o! Ban-ara

    hills !orms steep scrap.

    ++ %;6#A5 :arallel to the streams Corm the 8on-u)ate shear

    emer)in) !rom 'ir-umla !ractures.

    tank parallel to the system

    +++ %#6;A2? :arallel to the stream !rom

    Hussainsa)ar tank

    + % 5# 5; :arallel to the >uartz veins Corm *ensional

    7d-acent to the miralam tank !ractures.

    3.2 Geotec%ica, site co%'itio%s o/ H&'era(a'

    *he Hyderabad district !orms part o! the upland plateau re)ion called the D&eccan

    :lateauE. +t is )enerally surrounded by rocky hills. :rominent amon) them are the Ban-ara

    Hills, 522 @ 10 m above mean sea level Amsl, with e$tension in the %# partF Golconda

    ran)e, 5/ @ 54 m above msl, in the outhF 'oula 7li Hills, 5/ @ 3 m above msl, in the

    north east part with the *irumal)hery hei)hts and Gunrock hills !ormin) the northern part.

    7 !ew isolated hillocks Ainselber)s are also !ound within the city like Red hills and

    %aubat pahad. *he rest o! the district is marked by a )enerally undulatin) terrain between

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    1. m and 522.1 m above msl with city clusters. *here are also here and there low6lyin)

    !lood plains !ormed by 'usi and Hussain sa)ar streams.

    *he soils in the district are mostly sandy and clayey loams and alluvial black soils,

    and the yellow sandy and clayey loams !rom the pe)matite and quartzose rocks. *he alluvial

    black soils are con!ined to the streams and their !lood plains. *he thickness o! the Residual

    soil varyin) 5m to /5m !ollowed by either &RH&R or basic rocks.

    eismic history o! Hyderabad city