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Abstract

An earthquake swarm occurred during 2020-2021 at the Perachora peninsula, in the eastern Gulf of Corinth (Greece), one of the most seismically active areas in Europe. In this work, we analyzed the swarm using a high-resolution earthquake catalog and advanced processing techniques. We employed both single-station and multi-channel template matching to produce additional detections of over 7,600 and 24,000 events, respectively. The resulting catalogs have different completeness magnitudes and location uncertainties for the added events. The frequency-magnitude distributions were characterized using the Gutenberg-Richter scaling relation, examining possible b-value temporal variations. We found that the seismic bursts associated with the swarm were short-lived and dominated the catalogs. Spatiotemporal clustering methods were used to analyse the swarm's evolution, showing that the seismicity rate significantly increased, likely due to a pore-pressure transient, without stress transfer caused by a major earthquake. Migration velocities, high b-values and clustering effects of multiplet families, observed at all time scales, suggest a pore-pressure triggering mechanism. Some anomalies in the frequency-magnitude distribution of the enhanced catalogs were observed, mainly attributed to the poor network coverage of the area of interest. Despite these limitations, the enhanced catalogs can be quite useful in studying the spatiotemporal properties of microseismicity in the region. This study highlights the importance of high-resolution data and advanced analytical techniques in understanding earthquake swarms in tectonically active regions.AcknowledgementsThe research project was supported by the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the “2nd Call for H.F.R.I. Research Projects to support Post-Doctoral Researchers” (Project Number: 00256).