ADRC Study visit to Kumamoto andADRC Steering Committee
Kumamoto, Japan 2016

THE SPITAK EARTHQUAKE
07 12 1988
07.12.1988

Vigen Harutyunyan
Head of Department of Data Acquisition
Processing and Analysis,
Western Survey for Seismic Protection,
Ministry of Emergency Situations,
Situations
Republic of Armenia

SEISMOLOGICAL PARAMETRS•Time – 7 of December 1988, at 11.41 by local time•

Location of the epicenter – close by Spitak city ((φ =40,9; λ=44,2 0)•

Magnitude M-7,0
MagnitudeM 7 0 (according to different estimations 6.9-7.1)
6 9 7 1)•Intensity in the epicenter-9-10 intensity by MSK-64 scale•

Sizes of epicenter zone - 10×60km2•

Depth of the hypocenter – about 10km (according to different data 2,5-15km)•Duration of the main event -35-45 sec.

•

Characteristics of seismic fault : the total length -37km, the maximal vertical amplitude-2,5m,

and the horizontal amplitude -1,5m, type thrust- slide, the angel of incidence of the zone of thefault – 600-800•

The most important dislocations: two faults – lengths about 10-11km, revealed on the surface(between the Spitak city and the village Gekhasar, near the village Alavar), seismic –gravitational
formation near the village Dzorashen,
Dzorashen on the right side of the river Getik.
Getik•

Character of the main event –multiple, in minimum consisting of 3 shocks, these 3 shocks

are more separating and happened with 5 sec. and 14 sec. time intervals

LOCATION OF DIFFERENT 3 SHOCKES OF THE MAIN EVENT OF SPITAKEARTHQUAKE OF 1988 DURING 35-45 sec

1-st shock2-nd shock
2-ndshock3-rd shockCharacteristics of the zone of destruction•

Area of the zone of destruction- 10 000km 2, where about 1 million
people lived•

Area of the zone of hard destructions ((limited byy the isoseismals of8-10 intensity marks)-3000 km 2•

Number of destructed cities-11
cities 11•

Number of destructed villages-58•

Number of suffered cities -21•

Number of suffered villages
villages-342342•

Number of the people left without shelter from the zone of theearthquake were evacuated 120 000 people and the 75 000 of thembeyond the bounds of Armenia

HUMAN LOSSES The total number of victims- 25000 people Including in the cities:
 Gyumri -17000
 Vanadzor-1200
 Spitak- 4000
 Akhuryan- 500
 Stepanavan- 120

OTHER STATISTICAL DATA
 250 000 people were injured
 12 500 people were hospitalized 514 000 hhomelessl
 120 000 people were evacuated from the earthquake zone

Material losses
Direct losses-about 14 billion US dollars•

Losses of dwelling space
space-9
9 million/m2 (18% of the republic dwelling fund)•170 industrial enterprises with average productive capacity of 1,9 billion US dollars
stoppedtd theirth i ffunctionti•

917 buildings of schools and other objects of national education for 20000 people,
250 objects of health care, 324 club- houses and cultural clubs, 2260objects ofnourishment were put out of action or destructed•

The life-lines suffered hardly: 40km of railways, 80 km of electricity cables come outof action.

•More then 2300 from 8461 architectural and cultural monuments suffered (155 wereruined thoroughly, 984 seriously damaged , 1216 were half- ruined ), at that the 179
architectural monuments were of international importance.

THE MAIN REASONS OF LOW SEISMIC STABILITY OF MULTY FLAT AND
COMMON BUILDINGS CONSTRUCTED BEFORE THE 1989•

Design of buildings with lowered level of seismic hazard.

•Th poor quality
Theli off construction.
i•Unpermitted changes in the constructions of buildings,
those increase the seismic vulnerability.

•Insufficient account of the all engineer- geological andseismic conditions of the construction surfaces.

•Design defects almost in the all types of buildings.

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3

2

Zone of aftershocks of Spitak earthquake 1988 by Nazaretyan

Histogram of quantity Spitak earthquake 1988. during 1988-2015 M >2.5

Histogram of aftershocks energy of Spitak earthquake 1988. during 1988-2015.with 105Joule.

CONCLUSIONThe aftershock zone of the Spitak earthquake of 1988 is separated by various specialists intosegments with different seismological characteristics.

The aftershock activity is going on
on. The process is divided into highly active (1988(1988-1991)
1991) andweakly active (from 1992 till now) periods.

Within the pperiod of 1996-2007 slightg activation of the aftershock p
process is observed in all thesegments, which is expressed in escalation of both the quantity of the aftershocks, and thereleased energy.

Certainly, since 1996 the 4th segment demonstrates significant activity in the weakly active
Certainly
aftershock period with both the quantity of earthquakes and the energy. It should be noted that
this segment corresponds to the most strong and intense shaking of the main event of the 1988
Spitak earthquake.

Against the backdrop of the attenuation of aftershocks’ amounts and their forces no certain
pattern of strong aftershocks is observed. Only the well-known opinion on that the probability ofrelatively strong aftershocks is greater directly after the main event can be confirmed.

Until 2016 the total released energy of the aftershocks of the 1988 Spitak earthquake is thesmall percentage of the energy released during the main event.

The majority of the total aftershock energy (98%) was released during the active aftershock
period (1988-1991).

Thank you for attention