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Seismological Study of the West Bohemia/Vogtland Swarm Region With Waveform and Catalog Data

Description: 

The Vogtland region is situated in the western part of the Bohemian Massif and extends over an area of 3500 km² across four state borders. It is intersected by the medium-sized Tertiary Eger Graben, Variscan terrain boundaries, and a small sedimentary basin. The area is a type locality for the study of mantle-derived, diffuse degassing of CO2 and the persistent occurrence of mid-crustal earthquake swarms. Quaternary maar volcanoes and crustal magmatic underplating indicate extended magmatic processes. Despite intensive research, the cause of the earthquake swarms has not been elucidated, and questions remain as to how shallow magmatic fluids penetrate, whether the apparent Moho upwelling and underplating zone correlates with an upwelling of the brittle ductile transition between 15-10 km depth. Another open question is why since 1985 the highest swarm energy release with Ml<4.5 occurs in a cluster below Novy Kostel, and why for about 15 years the swarm has been migrating with each new cluster in a well-defined fault zone to the north and south, reaching shallower levels in recent years. To date, the Novy Kostel swarm extends over 35 km in length and 12 to 8 km in depth. The sources cover strike-slip, normal and thrust mechanism.

We follow three approaches to explore the swarm region: (1) improve the existing dense seismic network by installing high-frequency 3D arrays as antennas to detect and locate the smallest events. So far, two swarm episodes have been recorded by this installation; (2) unify the existing seismic catalogues from different surveys using a common velocity model and modern relative locations; (3) use of machine learning phase detection, migration and stacking techniques with the dense network data for the preiod 2018 to 2024 to reduce the completeness magnitude and study the anatomy of swarms in the initial activity phases. This comprehensive approach will answer the question of whether the distribution of the deepest micro-earthquakes follow the upwelling brittle ductile transition over the region of CO2 degassing and swarms.

Session: Advances in Operational and Research Analysis of Earthquake Swarms -II

Type: Oral

Date: 5/3/2024

Presentation Time: 04:30 PM (local time)

Presenting Author: Andrés

Student Presenter: No

Invited Presentation: 

Authors