Earthquake Data

Figure 1 

On April 25 2002, at 17:41:19 UTC the earthquake with magnitude 4.3 occurred in Tbilisi, Georgia. In the city of Tbilisi the intensity VI (by MSK-64) was felt. The earthquake was also felt in Armenia: Vanadzor city (intensity IV, MSK-64), Gjumri (intensity III, MSK-64) and Yerevan (intensity III, MSK-64 in some districts).

The event was recorded by Armenian NSSP National Seismological Network.

Figure 1 shows IRIS GNI recording.

Figure 2 shows the epicenters of 1896 Rustavi historical and Apr.25.2002 Tbilisi earthquakes.

It was the second earthquake with epicenter nearby Tbilisi during this month. On April 11, at 16:38:23 UTC, M=3.4, intensity V earthquake was felt in the city.

Figure 2

Earthquake bulletin.

Date-time                    2002.04.25., 17:41:19 UTC

Location                       41.67N; 44.82E 

Depth                           2.5 km

Magnitude                   4.3

Reference                    20 km SW of TBILISI,

                                      Republic of Georgia.

Source                          Armernian NSSP.

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Earthquake Consequences

7  people killed, 30 injured, 2500 buildings damaged, Tbilisi population is in stress.

Figures 3-9 show examples of damaged buildings in various sites of Tbilisi city.

Figure 3

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Figure 9

Armenian Government Response

After recording the Tbilisi earthquake Armenian NSSP had immediately reported the event to the Prime Minister of Armenia and Government of Georgia.

On the morning of the next day the Government of Armenia in coordination with Government of Georgia had rushed an 18 member fully equipped and experienced Armenian NSSP Task force multi-disciplinary team for relief operations in earthquake affected Tbilisi area. The team has included seismologists, structural and communication engineers, geotechnicians, physicians, physiologist, an emergency manager. As it was requested by the Government of  Georgia the formal charge of the team was as follows:

1. To provide scientific and technical expertise and multi-disciplinary assistance to the authorities of the Government of Georgia and Tbilisi municipality with respect to immediate post-earthquake relief efforts including: to establish a temporary array of accelerographs in different parts of Tbilisi city to record aftershocks; to recover malfunctioning Georgian accelerographs in Tbilisi; provide rapid engineering assessment of the geotechnical conditions in most affected districts of the city; provide inspection of the damaged structures hazardous for public and built environment; provide studies aimed to understand the reason of such inadequate consequences of the moderate earthquake M=4.3; to provide psychological, as well as medical and rescue assistance to people if needed.

2. To transfer earthquake monitoring data of Armenian NSSP to Georgian colleagues, as well as experience of immediate post-earthquake countermeasures.

Besides Armenian NSSP Task Force Team, the Armenian Mission headed by S. Balassanian, President of Armenian NSSP, Government of RoA, included: Governor of Lori Marz (Region) Mr. Henrik Kochinian, Deputy Mayor of Yerevan Mr. Vardan Vardapetian and Assistant of Prime Minister of the RoA Mr. Ararat Gomtsyan, as well as representatives of Ministry of Health, Ministry of Urban Development, Emergency Management Administartion.

The team was met and briefed in Tbilisi by Armenian Ambassador in Georgia Mr. Georgij Khosroev and officials of the Government of Georgia.

After the completion of disaster relief operations, Armenian Task Force Mission has submitted the brief reconnaissance report to the State Minister of the Government of Georgia.

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Armenian NSSP Task Force Team Actions

1. The aftershocks of Tbilisi earthquake have been recorded  in various sites of Tbilisi city. The recordings have shown the dominant period of ground motions as T_max=0.15 sec.

2. The study of the geotechnical conditions shows that there are very poor soil conditions in the most affected districts of the city.

3. The inspection of 65 damaged buildings shows that all of them were in very poor state before the earthquake.

4. Armenian NSSP analysis aimed to assess the further development of earthquake scenario has been transferred to Georgian colleagues and reported to the State Minister of the Government of Georgia. Based, on Armenian NSSP monitoring data the scenario predicted that any strong earthquake should not be expected in the nearest future.

5. Several interviews of S. Balassanian, Head of Armenian Mission, aimed to public stress recovery have been provided by Georgian TV and press.

-                -  the reason of extensive damages caused by moderate earthquake M=4.3 has been explained by S. Balassanian as resonance effect in soil-construction interaction (T₀=0.15 sec. of ground motion and natural frequency of buildings);

-                 -   the reason of 7 people killed has been explained as a result of unawareness of public about seismic hazard and risk, as well as behavior in case of earthquake;

-                 -    the reason of public stress has been explained as lack of understandable earthquake information.

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