Web-based macroseismic intensity study in Turkey: entries in Ekşi Sözlük

Abstract. Eksi Sozluk is one of the most visited websites in Turkey. Registered users of the website share their knowledge about any topic on an internet forum-like environment. In this study, we collect the user entries on the topics of 20 earthquakes in Turkey and the surrounding area. Entries with city and district level information are converted to intensity values. Shape maps of the earthquakes are created by using a ground motion to intensity conversion equation. User entries and created shake maps are compared. It is found that entries correlate with the predicted intensities. It is also found that local soil conditions and building types have an amplifier effect on entries in the web site. Several entries in the earthquake topics have magnitude estimations. Difference between predicted and observed intensities also vary with distance. Users are able to predict the magnitudes of the earthquakes with ±0.54 misfit. This study shows that Eksi Sozluk has a potential to be a reliable source of macroseismic intensity for the earthquakes in Turkey, if the felt reports have been collected with a predetermined format.