The earthquake stress drop is a key parameter that represents the difference in stress levels on a fault before and after an earthquake. Calculating it is important to understand the energy released during earthquakes, understand the physics of the earthquake source and it is also an important ingredient in estimating ground motion. However, calculating it accurately is tricky, mainly due to problems of data quality and resolution, and the assumptions made in individual approaches which difficult comparison across studies. We are honored to contribute to the BSSA Special Section “Improving Measurements of Earthquake Source Parameters” with a study on source parameters of < 1500 micro-earthquakes in the Marmara region of the North Anatolian Fault. After strict quality selection, we applied and compared the spectral fitting approach and generalized inversion technique, two independent methodologies with different assumptions. Analyzing the dataset with consistent trends from both methods, we observe the smallest stress drops located on the portion of the fault that is partially creeping, while the largest stress drops are located on a fault jog within the locked part. The results and datasets are part of the supplementary materials of the paper. This study benefited from very constructive team work within different sections of the GFZ Potsdam and we learn a lot on the way! Feedback is always welcome.
The paper can be accessed here.