Seismic Swarm S20240303.2: Analysis of Recent Activity in Greece

A seismic swarm designated S20240303.2 occurred in Greece from 19:35 on 2 March 2024 to 04:52 on 8 March 2024. Over 129 hours and 16 minutes, the swarm produced 236 earthquakes. This event aligns with Greece's established pattern of episodic seismic swarms driven by regional tectonics.

Greece occupies a complex tectonic setting at the convergent boundary between the African and Eurasian plates. Subduction along the Hellenic Arc generates frequent seismic activity, with swarms often linked to fluid migration or stress adjustments in the crust. The area has recorded multiple swarms since 2000, totaling eight events. These occurred in 2003 (one swarm), 2007 (three swarms), 2014 (two swarms), 2015 (one swarm), and 2018 (one swarm). Such clusters typically feature low-to-moderate magnitudes and shallow depths, reflecting the region's active fault systems.

Analysis of the first 100 events reveals consistent characteristics. Magnitudes ranged from 2.0 to 3.6, with the largest reaching 3.6 on 4 March at 07:06:44 UTC. Depths were predominantly shallow, clustering between 0 and 16 km, though isolated events extended to 30 km. Many events occurred at 5 km depth, indicating activity within upper crustal layers. Temporal distribution showed peaks on 3 and 4 March, with multiple events exceeding magnitude 3.0, including several at 3.5. Depths varied modestly, often stabilizing near 5–9 km during higher-magnitude phases.

The swarm's progression suggests a typical sequence of clustered microseismicity without a dominant mainshock. Early events on 2 March initiated at depths of 4–9 km, followed by a dense series of magnitude 2.0–3.5 quakes on 3 March. Subsequent days maintained similar magnitude and depth profiles, with gradual decline toward the swarm's end. No events in the initial 100 exceeded magnitude 3.6, underscoring the swarm's moderate intensity.

This activity contributes to ongoing monitoring of Greece's seismic hazards. Historical swarm frequency since 2000 indicates recurring patterns that inform regional risk assessment. Continued observation supports understanding of crustal dynamics in this tectonically active zone.

References:
SeismoSight internal swarm classification data for S20240303.2 and historical statistics.
USGS Earthquake Hazards Program reports on Hellenic Arc tectonics.
European-Mediterranean Seismological Centre regional seismic summaries.