The 1983 Biga earthquake hit northwestern Turkey

Turkey

Turkey , known officially as the Republic of Turkey , is a Eurasian country located in Western Asia and in East Thrace in Southeastern Europe...

 on July 5, 1983. Responsible for five deaths and approximately twenty-six casualties throughout Biga

Biga, Turkey

Biga is a town and district of Çanakkale Province in the Marmara region of Turkey. It is located on the Biga River, 90 km northeast from Çanakkale city centre. According to the 2000 census, population of the district is 80,982 of which 37,196 live in the town of Biga...

 and Erdek and damage in Istanbul

Istanbul

Istanbul , historically known as Byzantium and Constantinople , is the largest city of Turkey. Istanbul metropolitan province had 13.26 million people living in it as of December, 2010, which is 18% of Turkey's population and the 3rd largest metropolitan area in Europe after London and...

, the earthquake measured 6.1 on the Surface wave magnitude

Surface wave magnitude

The surface wave magnitude scale is one of the magnitude scales used in seismology to describe the size of an earthquake. It is based on measurements in Rayleigh surface waves that travel primarily along the uppermost layers of the earth...

 scale. It shook places as far away as eastern Greece. The United States Geological Survey

United States Geological Survey

The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The organization has four major science disciplines, concerning biology,...

 listed the earthquake among the "Significant Earthquakes of the World" for 1983.

Geology

The Biga Peninsula is an area marked by active faults including strike-slip movement and en echelon divergent

Divergent boundary

In plate tectonics, a divergent boundary or divergent plate boundary is a linear feature that exists between two tectonic plates that are moving away from each other. Divergent boundaries within continents initially produce rifts which produce rift valleys...

 basins.

The earthquake was preceded by a foreshock

Foreshock

A foreshock is an earthquake that occurs before a larger seismic event and is related to it in both time and space. The designation of an earthquake as foreshock, mainshock or aftershock is only possible after the event....

 nearly a year prior, and was followed by aftershock

Aftershock

An aftershock is a smaller earthquake that occurs after a previous large earthquake, in the same area of the main shock. If an aftershock is larger than the main shock, the aftershock is redesignated as the main shock and the original main shock is redesignated as a foreshock...

clusters.