To get as far as possible general and complite understanding
about the consequances of the Spitak earthquake  which  took
place on December 7,1988 immediately after its manifestation
of activity I with a group of specialists went to  Leninakan
on the next  day  after  the  earthquake.It  was  also  very
important  for  me  to  see  what  state  the  Institute  of
Geophysics and Technical Seismology  was  in,especially  its
staff because I am one of  the  founders  of  the  Institute
where  I  worked  for  10  years  /1961-1871/and  aided  its
development.It's necessary  to draw your  attention to  the
fact  that  the  Institute  was  founded on  the  initiative
of  academician V.A.Ambartsumian.The academician of  Academy
of  Sciences of Armenian SSR A.G.Nazarov was appointed the
head of the Institute.
I was horrified by what I saw and first of all,of  course,by
victims of the earthquake and by  the  state  of  people  who
survived,their sorrow and sufferings.I was also horrified by
devastating destruction of buildings and structures  of  the
dearl loved colourful town  where  I  walked  for  10  years
during my stay in Leninakan.
I know the consequences of  destructive  earthquakes.When  I
was   a   postgraduate,    I    examined    together    with
L.V.Shachsuvarian  the  Burakan  earthquake   of   1949   of
intensity 7 on the scale on the MSK-64 which took place in
Ashtarak region of  Armenian SSR.I studied the consequences
of many  destructive earthquakes in the USSR and abroad.
But the Leninakan earthquake was something  extraodinary.The
destruction and collapse of buildings  and  structures  were
very unusual.They took place within the space  of  buildings
and structures which increased number of  victims.This  kind
of destruction could happen only in case of a great vertical
component which was probably  greater  than  the  horizontal
component of the earthquake vibrations.
On that day and after it many  specialists  of  Armenia  and
other republics of the USSR came to examine the consequences
of  the  earthquake  in  Leninakan,Kirovakan,Stepanavan  and
adjoining villages.After the discussion of  the  examination
and exchange of views "The Conclusion  of  Investigation  of
the Spitak Earthquake of 1988 and Proposals for Guaranty  of
Seismic Qualities of the Buildings and Structures,Safety  of
Inhabitants    and    Non-standard     Facilities     During
Earthquakes"  was  signed  by  14  specialists.In  it   some
preliminary data conneted with makroseismic  examination  is
made into a whole.It's  established  that  the  majority  of
framework   and   panel   buildlngs   in    Leninakan    are
destroyed.Stone buildings collapsed  and  there are many
stone  buildings with extensive damage.Works,fabrics and
shops were completely  destroyed.The  Kirovakan   Group   of
Chemical  Enterprises is in a wrecking state.The works and
fabrics  in Spitak were completely destroyed almost all the
educational  institutions,schools,kindergartens,maternity
homes,hospitals   were destroyed.In  Spitak  rural  buildings
 and  individual   houses were destroyed.The same kind of
destruction  was  in  neighbouring regions.There were
buildings which plunged into  ground.In the epicenter zone
the permanent way  was  heavily deformed and rails  were
crooked.There  were  collapses  of rocks.There appeared very
wide clefts in  the  ground.In the  gaps of rocks  there
appeared  extensive  damages  of  near vertical direstion.The
bridges were also heavily damaged.
So the intensity of the earthquake in the epicenter zone was
10 and in Leninakan-9.Later  I investigated thoroughly this
earthquake including additional materials and as a result  I
had  clear  understanding  of  the   mechanism   of   Spitak
earthquake which took place on  December  7,1988.I  want  to
give an account of it.
Now we can be sure that the Spitak earthquake  was  a  uique
one,essentially different from others.
To my mind the most important thing about it  was  the  fact
that there were two earth tremors.They differed in intensity
by 1.The records of the Leninakan Seismic Station show this
( the component B-3,the component C-U and the  vertical  one
are not within  the  scale).The  records  of  the  Gukassian
Seismic Station also show this ( only three components were
   The intensity of the first  shock  of  the  Spitak
earthquake December 7,1988 in Leninakan according to seismic
instruments of the seismic stations was
  in 24 Spandarian St. the maximal  deviation  was  15 mm
-the upper limit for earthquakes with intensity 9,
  in 5 Leningradian St. the maximal deviation was 18  mm
-the  lower  limit  for earthquake with intensity 10  (the
reccords were made by L.A.Mchitarian).
But if we take into account the  fact  that  besides  the
main  shock of intensity 9-10 in Leninakan,there was a second
one  of intensity 8-9 which happened appoximately  in  4
minutes  after the first one,we shall see a very tragic
pisture,when  the buildings,drived to the limit of their
firmness received the shock and collapsed.
The norms and rules for construction in seismic  regions  in
the USSR and abroad don't take into consideration this second
shock. We drew  attention  to  it  approximately  20  years
ago.We  investigate  this  problem  for   two   years   in
Yerevan Polytechnic.
We also want  to  underline  that  the  destruction  of  all
buildings  and  structures  was   approximately   the   same
with some deviations.They took place as a result of the loss
of vertical stability of buildings and structures because of
combined  vertical  and  horizontal   components   of   high
intensity  seismic  force.There  took  place  at  first  the
destruction of some parts of buildings and structures  which
were  not  important  and then this   destruction   caused
the  destruction of important parts of buildings and
structures.  As  a  result  the  buildings  and   structures
collapsed inside and sometimes plunged into ground  at  a
certain depth.This kind of destruction could take  place  if
the vertical component was rather high,which could happen in
case of near vertical incidence of break plane in  epicenter
and in case of large seismic focus near  Leninakan.The  fact
that vertical  component  was  very  high  is  confirmed  by
analysis of data  got  by  many  pendulums  seismometers  in
Leninakan and Yerevan.This was  also  confirmed  by  out  of
scale records of the Leninakan seismic station (the vertical
and the maximal horizontal C-U components).The American data
got  in  epicenter  zones  of  earthquakes  shows  that  the
vertical and horizontal components of heavy aftershocks  are
roughly the same which once again confirms our point of view
that the vertical component was the  decisive  one  in  this
In norms and rules for construction in seismic regions in the
USSR and abroad the vertical component  as  a  rule  is  not
taken into consideration.
During the Spitak earthquake of December 7  1988  a  certain
role was played by resonance,the duration of vibrations, and
the interaction of buildings and structures with their bases.
Generalizing experience we must note that in the  norms  and
rules for construction in seismic regions  here  and  abroad
these very  important  circumstances  were  not  taken  into
consideration which caused tragic events.This  circumstances
must be taken into account while projecting and construction
of  new  buildings  and  structures  in  the  regions  which
suffered after the Spitak earthqake of December 7  1988  and
also during working up new norms and rules for  construction
in seismic regions in future.
There can appear the following questions:
   What can be said about the quality of construction?
High quality of construction is one of  the  most  important
things.It depends on the quality of  construction  materials
and construction work for combined buildings and  structures
and   on   the   quality   of   erection   for    monolithic
construction.The quality of construction in the USSR is as
high as necessary.
It can be said about all the regions and,I  repeat,about  the
seismic regions too,where the  quality  standards  are  very
high.In  this  connection  it's  necessary  to  develop  new
approaches for quality standards in seismic regions.
As to the Spitak earthquake of December 7,1988,it was  of
great intensity (9-10) which was several times  higher  than
the designed one for buildings and structures,there were two
shocks,and the vertical component was very high.
This was not taken into account in norms and structures  for
construction of buildings and structures in seismic  regions
and  because  of  it  these  factors  were  not  taken  into
consideration  during  the  projectihg  of   buildings   and
structures in seismic regions.
So,quality is  one  of  the  most  important  principles  of
construction in seismic regions.Among other principles there
are the choice of territiry,rational projects for  buildings
and   structures   and   lowering   of   their   weight,even
distribution of seismic loads by means of securing  symmetry
and uniformity of constructions,their plastic qualities.
  How will you explain that the  low  stone  buildings  were
  often more stable?
There was collapse and destruction in stone buildings  too.4
and 5-storeyed buildings  were  destroyed  as  we  mentioned
above in spite of antiseismic measures  and  the  fact  that
during their projecting the  vertical  component  was  taken
into account.But during the earthquake the seismic force was
2-3 times higher than the calculated one .1-3-storeyed stone
buildings with and without  antiseismic  constructions  were
destroyed less because of  their  stability.These  buildings
didn't collapse though they  were  in  a  way  destroyed.The
horizontal force in  these  buildings,as  we  can  see  from
instrumental data got  in  Leninakan,was  essentially  less
than that in 4-5-storeyed buildings.
Besides  the  stone  buildings  as  well  as  framework  and
frame-panel ones errected by means of lifting of floors were
more stable when they were less in  size,because  they  were
firmer in vertical direction.
The large size panel buildings during  the  earthquake  were
much better.It can be explaned by the fact  that  they  were
firmer and had cell structure.
In conclusion it must be stated that the  intensity  of  the
Spitak earthquake of December 7,1988 in Leninakan  according
to the State Standard number 6249-52 was  fixed  as  9-10.In
different parts of the town the intensity was  different  (9
or 10) and was higher than that for which the buildings  and

structures were projected for 5 times (they  were  projected
for the intensity 2 )
           The Chairman of the Problem Council for
           Seismology and Seismic Construction of
           the Academy of Sciences of Armenian SSR
                    Prof.Boris Karapetian