SAMPLE QUESTION FOR MY UPCOMING TEST.
COULD YOU PLEASE GIVE ME ANSWER & EXPLANANTION ?

A fault passes within 10 km of the site of a bridge over a river. It is
believed that the bridge is able to withstand earthquake shaking equivalent
to the 50-year earthquake on the fault. The fault shows clear
seismotectonic correlation and its seismicity is adequately described by
the Gutenberg-Richter cumulative frequency-magnitude relationship

log10 Nc = 4.1 ? 0.91M

where Nc is the cumulative number of earthquakes exceeding magnitude M.
Most of the significant earthquakes nucleate at around 10 km focal depth
and ensuing peak ground acceleration (pga), a cm s-2, attenuates with
distance r km as

a = 2164 e0.7M (r + 20)-1.8

What pga is the bridge likely to experience corresponding to the 50-year
earthquake? A small town has grown up next to the bridge and has not been
subject to earthquake design codes. What are the likely immediate reactions
of the population and consequences to the town buildings when the 50-year
earthquake occurs? [Assume that MSK intensity is given by I = 3.3log10a +
0.05]

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Clarification of Question by overloaded-ga on 01 Nov 2002 09:11 PST

a = 2164 e ^ 0.7M (r + 20)^ -1.8