Constraining Source Properties of the 1894 Istanbul Earthquake

The Marmara region is one of the most active tectonic regions with its high population and rapid but irregularly growing cities in Turkey. Located in this active zone, Istanbul has always been under the danger of being hit by destructive earthquakes, which in the past have caused serious damage in the city more than once. Major earthquakes to affect Istanbul during the Ottoman period took place in 1509, 1766 and 1894. As the latest one, we have relatively rich knowledge about the 10 July 1894 earthquake. The 1894 earthquake resulted in 474 losses of life and 482 injuries.  Around 21,000 dwellings were damaged, which is a number that corresponds to 1/7 of the total dwellings of the city at that time. Without any doubt the exact loss of life was higher. Because of the censorship the exact loss numbers remained unknown. Researchers have been split in opinion about the intensity, epicenter, magnitude, and rupture length of this event. The main target of this study is to have a better insight on the possible location of the 1894 earthquake with the help of damage analysis and ground motion modeling. Ottoman Empire archive records, scientific reports and papers, newspapers, government correspondence, letters, notes of voyagers and diaries are the major sources to make an evaluation on the type and extent of damage. An intensity map associated with the 1894 earthquake is prepared based on macro-seismic information, and damage analysis and classification. Various information types contained in the old city maps, municipal boundaries, and the population information have contributed to this assessment. Obtained damage information is presented, evaluated and interpreted.  For earthquake modelling the ELER (Earthquake Loss Assessment Routine) software is used. Using the ground motion module of ELER, several scenarios are modeled having different source, path, and site parameters. The resulting ground motion distributions are compared with the damage and intensity maps to provide a first-order assessment of the earthquake source parameters of the 1894 earthquake.