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Subject: Monitoring vibration

Monitoring vibration

From: Michael Maggen <michaelm<-at->
Date: Tuesday, December 1, 2009
Gali Beiner <galibeiner [at] hotmail__com> writes

>I am an archaeological conservator at the Bible Lands Museum,
>Jerusalem, Israel We are currently monitoring vibration and shock
>due to construction work taking place next to our museum. ...

A few years ago we at the Israel Museum Jerusalem--which is located
300 meters opposite to your museum the Bible Lands Museum--shared
worries and concerns of the same nature you posted here.  We were
expecting massive construction work to take place just beside (30
meters) the Shrine of The Book which is the site of the Dead Sea
Scrolls.

Naturally our concerns grow bigger due to the fact that future work
required soil and rocks removal for lowering surface level of 450
acres nearly by 3.5 meters (10 feet) deep. This massive work is
intended to be the foundation for our huge 80 BC ancient Jerusalem
model, the biggest one in the world. The hard rock could be removed
by three possible options:  controlled charges (explosives), sawing,
or braking (30/50 ton breakers) the rocks.

The Israel Museum hired experts who conducted a geo-physical survey
to test shock and vibrations which could result from of future work
and possibly release dangerous shock waves. 7 geophones (data
loggers) were left in the area between the future working site and
the site of the Scrolls to test series of shock waves caused by
artificial shockers simulators. The geophones recorded and measured
the ground movements in specific time.

There is a complicated equation called "scaled distance" which
describes the distance of the particle with relation to the amount
of energy released from the specific work action such as explosives
or a heavy breaker. German standard for safety of sensitive
buildings (DIN 4150) from shock is the lowest one in the western
world:  2.5 millimeter per second.  This means that if the a shock
waves moves the building up to 2.5 millimeter in 1 second the
building is safe.

The measurements in our site proved that various possible working
methods such as controlled charges, sawing, breakers of 50 or 30
tons, and bulldozer or trucks did not exceeded 2.5
millimeter/second. The company experts calculated the safer working
distance alluded for each of the mentioned jobs. On top of the fact
that using controlled charges was more economical (and still safe)
it was decided use the sawing and breakers methods.

After the completion of the work, records proved that shock and
vibrations were far below the level limits. We did not notice any
change nor any other phenomena on our sensitive materials namely
Dead Sea Scrolls.

I strongly recommend that you contact the company we worked with:
GEOTEC <URL:http://www.geotec.co.il/>. I think they are very
reliable and professional as well.

Michael Maggen
Head of Paper Conservation
The Israel Museum Jerusalem
PO Box 71117
91710 Jerusalem Israel
+972 2 67 08808
Fax: +972 2 6771332


                                  ***
                  Conservation DistList Instance 23:20
                 Distributed: Sunday, December 6, 2009
                       Message Id: cdl-23-20-002
                                  ***
Received on Tuesday, 1 December, 2009

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