Resonance frequency as a proxy for vulnerability as well as hazard
assessment in the context of recent 6.4 Assam earthquake
Abstract
We report here a preliminary investigation on site effects in a highly
populated zone of academic importance. The study area is mostly
characterized by its alluvial sediments. Due to its rapid development
with construction of high-rise buildings and presence of active Kopili
fault nearby, the site effects analysis in this area has become very
crucial which is further fueled by a strongly felt earthquake of 6.4 M
occurring recently; whose epicenter was just 40 Km away from this study
area. Accordingly, an attempt is made to assess site related parameters
by accruing ambient vibration records at 16 single stations covering.
Via horizontal to vertical spectral ratio (HVSR) analysis, we estimate
the resonant frequencies. Likewise, we compute the HVSR amplification
values. Apart from this, liquefaction vulnerability indices were
estimated for the study region. With a fair corroboration with borehole
data, the findings reveal a low velocity zone. The heterogenous
distribution of resonant frequencies and assorted amplification
implicate a varying overburden thickness; thereby augmenting the Kg
values at certain places. In the context of the recent 6.4 M earthquake,
the results are poised to play a pivotal role so far hazard mitigation
is concerned.