Next: The experiment Previous: Abstract
Next: The experiment
Previous: Abstract
As a consequence of the January 17, 1994 M 
, depth=19 km Northridge
earthquake (USGS and SCEC, 1994), Sherman Oaks and mid-Santa Monica
experienced much greater damage than neighboring regions at similar
distances from the epicenter. This is illustrated in Figure 1 which
shows that the distribution of red-tagged buildings (Marshall and
Stein, 1994) has higher concentrations in these areas than in the
immediate surroundings. The boundary between the heavily damaged and
the slightly damaged zones is relatively sharp; the transition takes
place over a distance of less than one kilometer. There is no
systematic difference in building types, building codes, or earthquake
resistance between the heavily and slightly damaged zones.
To understand the cause of the concentrated damage, we installed an array
of seismic stations to record aftershocks in the two heavily damaged
areas as well as along two profiles across the San Fernando valley and
the northwestern part of the Los Angeles basin.
The data set has been used to study localized amplification factors
[Gao et al., 1996] using a Bayesian inversion approach
[Jackson and Matsu'ura, 1985], and to test the validity
of the use of coda wave amplification factors as an indication of S-wave
amplification factors [Liu et al., 1996],
as suggested by Kato et al. [1995]. Other work such as
finite difference waveform modeling and
small array analysis [e.g. Frankel et al., 1991] are
currently being conducted.
