Earthquake Detection Near the Central Anatolian Fault Zone Using Continuous Data from the CD-CAT Experiment

Abstract:

In central Turkey, the Anatolian plate is actively being pushed by Arabian plate convergence in the east and pulled by Hellenic arc retreat to the west; however, there is also ample evidence of internal plate deformation. This region provides an opportunity to gain a deeper understanding of the transition from collisional (eastern Anatolia) to escape tectonics (western Anatolia). The Continental Dynamics: Central Anatolian Tectonics (CD-CAT) experiment, consists of a dense array of 71 broadband seismometers that span nearly all of Central Anatolia, including the Central Anatolian Fault Zone (CAFZ), Tauride Mountains, North Anatolian Fault Zone (NAFZ), and East Anatolian Fault Zone (EAFZ). We use over 5 months of continuous seismic data to locate earthquake hypocenters in the CAFZ and surrounding region using Hypoellipse. Over 135 local events were detected during analysis of the first month of data. We have developed and calibrated an automated triggering algorithm to automatically detect events throughout our network. By comparing solutions with the Kandilli Observatory and Earthquake Research Institute, we have also tested the effects of using a variety of 1-D velocity models on the hypocentral distribution and find most solutions to be relatively stable for hypocenters within the center of our network. Preliminary results show clustering of events along the EAF, as expected; however, the CAFZ, generally considered to be less seismically active, also shows a significant amount of seismic activity that is consistent with internal plate deformation. Additional seismicity is observed along the NAF, and near volcanically active regions of central Anatolia. These local earthquake hypocenters will help constrain crustal deformation patterns as well as crustal scale magma bodies that are associated with the volcanic activity in central Anatolia. We also plan to combine local event locations with regional events to measure seismic attenuation across central Anatolia.