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Geotechnical News December 2011
Earthquake Early Warning
System can shut down plants
and critical processes
In 2011 an earthquake and tsunami
severely damaged the Fukushima
Daiichi power plant in Japan.
As a way of preventing similar fu-
ture incidents, Weir-Jones Engineer-
ing Consultants Ltd. of Vancouver
has introduced an innovative technol-
ogy that provides advance warning of
an impending earthquake. Known as
the Earthquake Early Warning Sys-
tem (EEWS), it provides operators
with enough time to bring processes
or equipment to rest or to deny access
to critical structures such as bridges or
tunnels before the onset of a seismic
event.
The amount of warning time de-
pends on the distance between the epi-
centre of the earthquake and location of
the EEWS. Normally, for shallow and
close epicentres this time difference is
a few seconds and for deep and distant
seismic events is up to two minutes.
Weir-Jones conceived the idea when
the Ministry of Transportation in Brit-
ish Columbia was looking for a way
to protect motorists who use a tunnel
that takes traffic under the Fraser Riv-
er south of Vancouver. By June 2009,
the EEWS was fully designed and de-
ployed at the designated location and
the system entered the test phase.
The system, which is the only in-
stallation to date, relies upon the out-
put from geophone sensor packages in
boreholes north and south of the tun-
nel. The boreholes are about two kilo-
metres apart and both sensor packages
have to produce similar signals within
a predefined time window for the ana-
lytical software to declare that a dan-
gerous seismic event is pending.
The EEWS consists of four major
parts: vibration sensors, data acquisi-
tion units, a central processing com-
puter and an alarm system.
It relies on the well-known phenom-
enon that the destructive energy of an
earthquake is related to large secondary
shear waves (S-waves) that are preced-
ed by the less destructive primary com-
pressive waves (P-waves). When an
earthquake occurs, the P-waves propa-
gate much faster through the earth’s
crust compared to the more destructive
S-waves. Based on this principle, the
scale of an impending earthquake can
be predicted by detecting and analyz-
ing the P-waves.
The EEWS detects and character-
izes P-waves and issues an alarm if the
magnitude exceeds the pre-set limit.
To achieve this, the EEWS constantly
monitors the ground motion in real-
time and searches for signatures of P-
waves of a strong earthquake.
Shutting down transportation routes,
plants or processes is costly and should
be avoided unless an imminent hazard
is foreseeable. To achieve a high level
of reliability and make the system not
prone to false alarms, multiple layers
of redundancy have been considered in
the EEWS design.
Contact: Iain Weir-Jones at
.
Boring Log Data on Rugged
Tablet PC
The newest version of WinLoG 4.5 can
now run on tablet pcs that use Windows
7 operating system. This new version
offers many great advantages for field
use:
• Rugged tablet PCs can withstand
water, dust, and are shock resistant.
Some can include cameras and
GPS.
• Logs can be completed in the field
and emailed to the office. Minimize
the amount of office work required.
• The data in the final log will be more
accurate, reduces the possibility of
transcription errors.
• Macros can be used to quickly insert
predefined text and symbols into
lithologic layers.
• Macros can be used to quickly add
standard well diagrams.
• The program is identical to the
desktop version, so there is no ad-
ditional learning curve.
For more information or to get a free
demo of the program contact
.
Instantel Partners with Brüel &
Kjær to Provide Noise & Vibra-
tion Monitoring Services
Large infrastructure construction
projects take several years to complete
and are often located within built-up
areas. This can give rise to significant
noise and vibration nuisance which,
if left unmanaged, can lead to project
delays and significantly increased
costs. Importantly, excessive vibration
from pile driving and other construction
activities can lead to damae to nearby
property and potential litigation.
Brüel and Kjær has been active for
many ears providing noise monitoring
solutions to manage noise nuisance
around the world and is pleased to an-
nounce a partnership with Instantel to
add vibration monitoring to its Noise
Sentinel managed services.
Contact: Ron Mask at Instantel, email:
