1979 Yılı Batı Türkiye Deprem Etkinliği
1979 Yılı Batı Türkiye Deprem Etkinliği.


Üçer S. B., Ayhan E., Başarır E., Sancaklı N., Alsan. ve Tezuçan L.

Özet.


Kandilli Rasathanesi deprem istasyonlarından elde edilen verilerle, 1979 yılı boyunca Batı Türkiye’deki Deprem Etkinliği, bu çalışmada yansıtılmaya çalışılmıştır. Bu dönemde, mevcut deprem istasyonlarınıa ek olarak Marmara Bölgesinde radyo bağlantılı ve beş istasyon oluşan yeni bir deprem ağı da faaliyete geçirilmiştir.. Böylelikle Batı Türkiye’de ve özellikle Marmara Bölgesinde gelişen deprem etkinliğinin daha ayrıntılı bir şekilde araştırılması olanağı doğmuştur. 1979 yılında en şiddetli deprem 5.1 magnitüdü ile Haziran ayında Çandarlı Körfezi’nde oluşmuştur. BU deprem ve artçıları Mayıs ayında Karaburun da 4.1 magnitüdlü deprem serisinden sonra oluşmuştur. Mayıs 1976 yılında başlamış olan Emet deprem fırtınasının bu yıl da devam ettiği gözlenmiştir. Temmuz ayında Dursunbey-Gökçedağ’da 4.8 magnitüdü ile oluşan depremi takiben. Eylül ayının sonuna kadar birçok artçı deprem oluşmuştur. Ayrıca yılın bu önemli deprem serileri dışında, sayıları ve magnitüdleri küçük olmakla beraber, Uludağ (Bursa), Savaştepe, Sapanca-Akyazı, Hendek, Marmara Denizi, Midilli Adası, Tefenni ve Milas’da da deprem etkinlikleri saptanmıştır.

Summary.


The The seismic activity of western Turkey during 1979 is represented in this paper. The dataused in this work were ohtained from the Anatolian seismic network and a telemetered network (MARNET) consisting of six seismic stations around Marmara Sea. Both networks are equipped wilh high gain short period, vertical component seismograph system and oparated by the Kandilli Observatory. The main seismic station is Kandilli Observatory (ISK) and it has three-component short period seismographs and two Wood-Anderson torsion seismographs. 1436 earthquakes, magnitudes generally larger than 2.5 have been located in the area between 35° 42° north latitudes and 25° 32° east longitudes. For the earthquakes in the Marmara Sea Region it was possible to reach a magnitude level of 1.5 byr the aid of MARNET data.

Herrin's travel-time tables have been used in a computer program for the determinations of earthquake locations. Depth calculations were not taken into consideration. Signal durations from the records have hcen used for magnitude calculations. The average values of the magnitudes were given when two or more stations were employed.

The listing of earthquakes contains, date (day, month, year), origin time (GMT), latitude and longitude, magnitude, root-mean squares of residuals (RMS), number of arrivals and quality of solutions, respectively.

Epicentre maps were drawn, according to the magniludes and the solution quality of earthquakes, Monthly maps have good, fair and poor solution qualities. In quarterly maps poor solutions have been excluded and in the annual map only good solutions are plotted.

During 1979 the main centres of actidty were:

1. Emet earthquake Swarm: The activity near to Emet town had started in May 1976. Nearly 250 shocks were located during the year. The highest activity was observed during the first five months of the year. The magnitude of the largest shock did not exceed 3.8.

2. Çandarlı Bay and Karaburun earthquake activity: In May, an earthquake with magnitude 4.2 occurred at Karaburun and in June another earthquake with magnitude 5.1 was observed in Çandarlı Bay, a dense activity observed until the end of June. Nearly 180 earthquakes Çandarlı Bay and 80 earthquakes at Karaburun were located.

3. Dursunbey-Gökçedağ earthquake activity: The main shock with magnitude 4.8 was recorded in Jul 18 1979. Several aftershocks occurred until the end of September.

4. Uludağ (Bursa) earthquake activity: The earthquake sequeuce started at the beginning of July and cortinued until the end of October. The highest activity was observed during August and September. The largest magnitude was 3.3.

5. Savaştepe earthquake activity: In October an earthquake cluster appeared in this area. Tile largest magnitude of this sequence was 3.9.

6. Sapanca-Akyazı-Hendek earthquake activity: During the year some scattered epicentres were observed in the area. The activity showed an increase in March, April and November. The largest shock with magnitude 3.7 was recorded in March.

7. Marmara Sea earthquake activity: The main earthquake clusters in this area were observed off coast or Marmara Ereğlisi (Tekirdağ) in April (mmax= 3.2) and in the north or Biga in August (mmax= 3.4).

8. Lesbos Island earthquake activity: This activity appeared on the island in January, April, August, and in the north of the island in September and December. The largest shock with magnilude 4.1 was observed in April.

9. Tefenni earthquake activity: It appeared in February, April and September. The largest magnitude was 4.2. observed in September.

10. Milas earthquake activity: The activity was observed in October. The latest magnitude was 4.0.