PSN-L Email List Message
Subject: New Zealand earthquake
From: Tangazazen@.......
Date: Mon, 6 Sep 2010 15:19:00 EDT
Hi All,
There has been some discussion on the latest New Zealand earthquake and
considering the magnitude, luckily no loss of life but considerable damage.
Most earthquake damage is due to the surface wave. The attenuation of
Rayleigh waves is significantly less than that of a body wave, approximately 1/
root of distance. For gravel and sands though, seismic velocity are low but
the dispersion can be quite high, that is the energy appears in lower and
lower frequency with distance. Certain types of clay particularly when wet
can exhibit thixotropic properties, that is a fall in viscosity with shear
stress as at Mexico city. Does anybody know of the geology of the area?
Resonance can be damaging to building and as a general rule of thumb is
about 10 c/s divided by the number of floors. Given the distance from the
epicentre one would expect the taller building to have sustain the most
damage.
Is there anybody in Christchurch who can though some light on any of this?
Martin Page
Hi All,
There has been some discussion on the latest New Zealand earthq=
uake=20
and considering the magnitude, luckily no loss of life but considerable da=
mage.=20
Most earthquake damage is due to the surface wave. The attenuation of Rayl=
eigh=20
waves is significantly less than that of a body wave, approximately 1/ roo=
t of=20
distance. For gravel and sands though, seismic velocity are low but=
the=20
dispersion can be quite high, that is the energy appears in lower and lowe=
r=20
frequency with distance. Certain types of clay particularly when wet can=
exhibit=20
thixotropic properties, that is a fall in viscosity with shear stress as=
at=20
Mexico city. Does anybody know of the geology of the area?
Resonance can be damaging to building and as a general rule of thumb=
is=20
about 10 c/s divided by the number of floors. Given the distance fro=
m the=20
epicentre one would expect the taller building to have sustain the most=20
damage.
Is there anybody in Christchurch who can though some light on=
any of=20
this?
Martin Page
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