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The work of an earthquake.
Can we prevent it? |
The history of earthquake prediction is long
and at most, fruitless. In the 4th Century B.C. Aristotle proposed
that earthquakes were caused by winds trapped in subterranean
caves and ancient Chinese and Italians studied special clouds
which were thought to be indicative of impending quakes. More
recently a group of scientists at the University of California,
Los Angeles claimed an earthquake approximately 6.5 on the Richter
scale will occur in Southern California by September 2004. It
didn't happen. The grim history of earthquake prediction led
some seismologists like Robert J. Geller from Tokyo University
to claim that it is practically impossible to predict earthquakes
and that it seems unwise to invest heavily in monitoring possible
precursors of upcoming earthquakes. Despite the long line of
failed projects and the harsh criticism sprung each time a new
earthquake prediction method was suggested, a small Israeli
company named Terramoto has recently proposed a three stage
method which its inventor, Meny Nachman, believes will not only
help predict earthquakes with very high accuracy but also be
able to stop some of them from occurring altogether.
Why earthquakes occur?
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The Earth's crust is broken
into a mosaic of moving tectonic plates. |
In order to understand Terramoto's idea we
first need to go deep underground in order to understand what
causes earthquakes in the first place. According to the theory
of plate tectonics developed in the 1960's the earth's interior
is made up of two layers, the outer lithosphere and the inner
asthenosphere. The lithosphere essentially "floats"
on the asthenosphere and is broken-up into ten major plates.
These plates are in constant motion relative to each other with
a typical velocity of a few centimeters per year. Although the
velocity in which the entire plate is moving is relatively constant,
the velocity in which material is moving along intersections
of plates, also known as fault lines, is not constant and is
believed to be changing due to irregularities in the material
composing these parts of the earth asthenosphere. These irregularities
are attributed to rocks, sometimes kilometers in size, which
are buried in the ground and can be found at times up to 20
kilometers below the surface. These rocks can locally stop the
movement along a fault line and by doing so accumulate tremendous
pressure which is released abruptly when the rock finally crushes.
This instantaneous release of mechanical energy is what we call
earthquake and the strength of the quake is dependent upon the
amount of energy accumulated in the rock over the years. Relatively
small quakes happen all the time near fault lines around the
world and although we usually do not feel them, the system developed
by Terramoto regards them as highly important signs that can
reveal much about an impending big earthquake.
Terramoto's
three stage method for detecting and preventing earthquakes:
Terramoto has developed a method based on existing equipment
which will map, predict and if possible prevent major earthquakes
from occurring along known fault lines.
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Geophone is an instrument used to detect vibrations passing
through the earth's crust. |
Mapping a number of measuring
stations will be placed along the fault line equipped with special
microphones called geophones (a standard seismological equipment)
which will be buried in the ground. Each geophone will be capable
of measuring the low frequency noise caused by faint earthquakes
and using triangulation techniques will locate the points in
the ground where pressure is building up. The idea behind this
method is that if in a specific point along the fault line we
measure a certain amount of energy release and in another point
along the fault we measure a similar amount of energy release
then we can assume the existence of a third point in the gap
between these first two points were energy, at least at the
same amount, is being accumulated.
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The drilling will be performed using
standard equipment from the oil industry. |
Predicting When a potentially
hazardous point is located, a deep ultrasound survey is performed
using equipment borrowed from the oil industry. The survey is
performed in order to locate the specific rock where the pressure
has accumulated. Using drilling equipment (again borrowed from
the oil industry) extract a sample of the rock and evaluate
its strength, and combined with the ultrasound scan determine
its size and shape. This data is then used to create advanced
mathematical models that can predict how much pressure the rock
could endure before succumbing to the sheer force of the tectonic
plate. The amount of pressure built up can be a good indication
of the possible force of the earthquake that can be unleashed
when the rock eventually shatters. In order to be able to give
an accurate time prediction of an upcoming quake, two lasers
will be placed each on a different tectonic plate and by measuring
the interference pattern they create it is possible to evaluate
the relative velocity in which the two plates are moving and
thus the rate of the energy accumulation inside the rock.
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In order to weaken a potentially dangers rock,
a deep underground explosions will be performed. |
Preventing When a
high-magnitude earthquake has been predicted it is possible
to drill up to 10 kilometers inside the ground and place explosives
inside the rock in order to perform a series of controlled blasts
to weaken the rock, gradually relieving the built-up energy
accumulated over the years.
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Dr. Shmulik Marco |
IsraCast
approached Dr. Shmulik Marco, from the Department of Geophysics
and Planetary Sciences at the Tel Aviv University, to get his
professional opinion on the method developed by Terramoto. Dr.
Marco explained that systems like the one suggested by Terramoto,
are important tools for saving human lives and as such are worth
much more than the amount of money that will be invested in
them. The idea behind the system is not entirely new, and although
there are some technological obstacles in the way, the main
reason such systems have not been implemented in the past are
more political then technological. According to Dr. Marco there
is a real need for rethinking priorities and reallocation of
funds to the field of seismology which suffered from heavy cutbacks
in recent years especially in the U.S. As for the method suggested
by Terramoto, the first stage (mapping) is definitely possible
and partial experiments of this sort are currently taking place
around the world. The second stage (predicting) is also possible
although it will pose great technical difficulties due to the
need to drill more than eight kilometers below the ground (there
are currently a handful of drilling teams working below this
depth around the world). The third stage (prevention) is the
least feasible at this point mainly due to the need to find
ways to detonate huge rocks deep inside the ground, in an extreme
environment of intense heat and high pressure. But even if the
third stage would not always be performed, advance warning can
give countries time to prepare quick response teams, strengthen
buildings and in some cases even evacuate people ahead of time.
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Mr. Meny Nachman,
Terramoto CEO |
Mr. Nachman, Terramoto CEO, told IsraCast
that despite the difficulties involved with deep earth drilling,
there are still many potentially devastating earthquakes which
are caused by rocks less then 8 km inside the ground. These
rocks can be reached using existing drilling equipment and the
blast can be performed inside the rock using a relatively small
charge that will create an initial crack in the rock, preventing
it from accumulating dangerous pressures. According to Mr. Nachman
Terramoto's system will be able to predict the center of an
upcoming earthquake with precision of within about one meter,
half a Richter scale in magnitude and a timeframe of between
a week and a month of its occurrence. Based on the data collected
it should be possible to predict earthquakes many years in advance
and thus either prevent them by a series of controlled explosions
or prepare for the event by strengthening buildings and evacuating
people.
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Kobe, Japan - 1995 |
Terramoto was founded by Mr. Nachman in 2005
and its new method is currently patent pending in the U.S. and
Israel. The development of the first stage of the system for
which Terramoto is seeking investors should cost less than one
million dollars, and the full system including six measuring
stations should cost approximately one million dollars upon
completion. When we factor these costs we should always consider
that besides the horrific loss of life we attribute to many
high magnitude earthquakes there is also a huge financial cost
attached to them. The 1976 Northridge Los Angeles 6.9 magnitude
earthquake demolished some 15,000 buildings resulting in a total
loss of around $15bn; in Kobe Japan the 7.1 magnitude earthquake
in 1995, cost $90bn to $147bn in repairs alone and resulted
in 180,000 buildings destroyed or seriously damaged. An accurate
reliable early warning system might have prevented these and
other human and economic catastrophes.
