The new Indonesian code for building design, SNI 1726:2012, has been issued recently. It
follows the concept of Risk-Adjusted Maximum Considered Earthquake MCE
R
used by
ASCE 7-10 and it provides maps of MCE
R
for the whole Indonesian Country. Development
of seismic risk microzonation of Semarang City is required for disaster preparedness and
hazard mitigation. The purpose of this research is then to propose the seismic microzonation
of Semarang City based on the seismic hazard analysis, site specific response analysis and
risk assessment.
The seismic hazard analysis is adapted from ASCE 7-10 to produce MCE
R
ground
motion at bedrock level for the whole area in the city by combining the results of
deterministic, probabilistic seismic hazard analysis, and fragility curves of buildings. The
analysis was performed by using calculation procedures, seismic source model, attenuation
functions, and geological and seismological data previously used to develop national seismic
hazard and risk maps by Team for Revision of Seismic Hazard Maps of Indonesia 2010.
The site response analysis and risk assessment were conducted by carrying onedimensional
ground
response
analysis.
Geotechnical
parameters
are
interpreted
from
previous
and
recent measurements and depth of engineering bedrock is estimated based on Single
Station Feedback Seismometer measurement. Two engineering bedrock elevation models
were performed to obtain the distribution of site response such as peak ground acceleration
(PGA), spectral acceleration at ground surface and amplification factor due to ground
motions at bedrock. The seismic microzonation is carried out by selecting time histories of
ground motion records for input motions in one-dimensional propagation analysis. Five
ground motions for all sources and five ground motions for shallow crustal fault sources
(with magnitude ranging from 6 to 7 and maximum distance 20 km) are collected from
worldwide historical earthquake database records. Site response analysis is then conducted
for each ground motion to obtain peak ground acceleration, spectral acceleration and
amplification factor.
Keywords: Seismic Microzonation, Seismic Hazard Analysis, Site Specific Response
Analysis, Single Station Feedback Seismometer Measurement