The Neuwied Basin within the East Eifel Volcanic Field (EEVF) is characterized by increased microseismicity, long hypothesized to be linked to the subsurface Ochtendung Fault Zone (OFZ). However, the source of this unrest remained elusive due to limited hypocentre resolution. Here, we present an extended local earthquake catalogue, compiled from a year-long Large-N deployment and a machine learning-based detection and location approach, including over 1000 microearthquakes recorded between September 2022 and August 2023. This high-resolution data set reveals new seismicity clusters, repeated waveforms and distinct temporal bursts of activity, suggesting fluid-induced earthquake triggering. Probabilistic moment tensor inversion for 192 high-quality events (Mw 0.6-2.7) resolves predominantly strike-slip faulting along the OFZ, with localized clusters of normal faulting nearby, potentially associated with a previously unknown border fault of the NWB. Notably, we observe systematic rotations in P-axis orientations along the OFZ, which we interpret as localized stress perturbations induced by an overpressured reservoir beneath the Laacher See volcano-the youngest explosive eruption centre in the EEVF. These patterns, coupled with elevated magmatic $\rm {CO}_2$ emissions in the region and high waveform similarity, suggest that active magmatic and transcrustal fluid processes are influencing the stress regimes and driving the seismicity in the NWB. Our high-resolution seismicity and moment tensor catalogue offers new insights into the interplay between tectonics and fluid-driven processes beneath the youngest volcanoes in the EEVF.

Recent clusters of deep, low-frequency earthquakes southeast of Laacher See in the East Eifel region of Germany suggest the presence of an active magmatic system in the lower crust and upper mantle. Measuring fluid data at the Earth's surface could help identify processes in the deep magma system. Dense and continuous monitoring is required to distinguish between environmental and deep processes, but this is rarely carried out. Here, we present a pilot study of an intracontinental, distributed volcanic field in the Eifel, where twelve measuring stations have been installed since 2020 in decommissioned CO₂ wells, mofettes, CO₂-rich springs, CO₂-rich soil, and a cold-water geyser. For the first time, fluid data is being recorded continuously with a high temporal resolution of up to 1 Hz. Interestingly, seasonal variations in fluid parameters are relatively small, and baseline data was determined within two to three years. Short-term transients were observed at individual network stations and were related to events such as heavy rainfall, atmospheric pressure waves, or local and distant earthquakes. However, over longer periods, we also observed trend changes in important magmatic indicators, such as helium isotope ratios, radon concentration, and water temperature. For instance, one location exhibited notable shifts in helium isotopes from 2021 to 2025, seemingly correlating with earthquake swarms at depth. These examples underscore the importance of establishing a network of fluid measuring stations, conducting continuous monitoring, and jointly evaluating meteorological, hydrogeological, geophysical, and geodetic data.

The East Eifel Volcanic Field (EEVF) in Germany is a densely monitored yet dormant distributed volcanic field comprising hundreds of Quaternary volcanoes, including the most recent eruption of the Laacher See Volcano ~13,000 years ago. The GFZ's Central European Volcanic Province Observatory (CVO) integrates data delivered by multiple partners: Seismic data, GNSS, a superconducting gravimeter, and fluid monitoring sites to detect subtle signals of volcanic and tectonic activity. This study focuses on microseismic swarms observed within the EEVF since January 2020. We present a multidisciplinary analysis of selected swarm sequences, with particular emphasis on their spatial proximity to recently mapped crystal velocity anomalies, interpreted as potential melt reservoirs. Notably, the suspected locations of partial melt reservoirs beneath the EEVF correlate well with the location of the DLF earthquakes. Most recently, a swarm of approximately 120 locatable events (Mw < 1.6) occurred near the Laacher See Volcano in October 2025, prompting considerable public and media interest. Preliminary moment tensor inversion and cross-correlation-based clustering indicate a highly self-similar sequence with oblique normal faulting to strike-slip faulting mechanisms in agreement with the regional stress field. Although the EEVF is not typically characterized by extensive swarm activity, our analysis reveals tens of tiny swarm sequences over the past six years. The Oct-2025 swarm illustrated the feasibility of a quick, multidisciplinary assessment of the EEVF; during this swarm, no co-seismic changes in ground deformation, fluid properties, or gravity were detected. In our ongoing work, we explore several hypotheses linking the microseismic swarms to fluid-driven processes near potential melt reservoirs.

The understanding of the magma system beneath intracontinental volcanic fields depends critically on our ability to resolve small-sized anomalies distributed over large areas of hundreds of kilometres. Magmatic reservoirs co-exist at different depths in the upper mantle and crust and may consist of extensive zones of crystal mush, swarms of sills and dikes of different ages and states, pore space saturated by volatiles or melt, or larger-volume, differentiated magma. Passive seismological experiments with a large number of sensors deployed with small interstation spacings, combining different types of sensors and fibre-optic sensor technology, have great promise for addressing the resolution to capture the distributed magmatic system. We report on a one-year, large-N experiment in the Quaternary volcanic fields of the Eifel, Germany, where more than 494 seismic stations were deployed and combined with a 64-km-long DAS cable and permanent stations. A cloud-based, open-source GIS system was implemented to address logistical challenges and ensure data quality combined with seismological analysis and visualisation tools. We present initial results to test the potential of such an extensive waveform database and automated processing for locating small earthquakes and imaging crustal and upper mantle anomalies using techniques such as ambient noise cross-correlation, receiver functions, and SKS splitting.

The East Eifel Volcanic Field in the west of Germany has received increased scientific attention in recent years due to new findings on ongoing deep magma-related seismicity and regional uplift. Related CO2-degassing phenomena in the region have also been investigated, more specifically in and around the Laacher See volcanic lake, formed by a series of eruptions ca. 13 ka BP. Present-day degassing activity in the Laacher See caldera is most notably evidenced by several gas seeps (i.e. mofettes) in the lake and its surrounding shore, emitting CO2 of magmatic origin. During two surveys in 2019 and 2021, several geophysical techniques were used to image and monitor this CO2 seepage, both in the water column and in the sedimentary infill of the lake. A multibeam echosounder was used to locate gas flares in the water column, visible by their high backscatter intensity, as well as the bathymetric expression of gas escape features on the lake floor. Additionally, high-resolution seismic reflection profiles were acquired with different acoustic sources at different frequencies. These profiles were used to identify accumulated gas in the subsurface, evidenced by enhanced reflections and acoustic blanking. Our results show that accumulated gas is present at different depths in the lake subsurface, from ca. 2 m to more than 25 m below the lake floor, making it possible to map out areas with high concentrations of free gas at different levels. Locations of subsurface gas accumulations often coincide with areas that have a high concentration of gas flares in the water column. Furthermore, depressions resulting from gas escape (i.e. pockmarks) can be identified on the lake floor bathymetry, linking the upward migration of CO2 gas in the subsurface to the seepage in the water column. Our data confirm that gas is actively migrating through the sedimentary infill and water column of Laacher See and illustrate the need for monitoring these gas migration processes, which can ultimately contribute to a better volcanic hazard assessment in the Eifel region.

The East Eifel Volcanic Field (EEVF) in the west of Germany has received increased scientific attention in recent years due to new findings on ongoing deep magma-related seismicity and regional uplift. The most recent volcanic event in the EEVF was the eruption of the Laacher See Volcano around 13 ka BP, which is well-studied in central Europe due to the Laacher See Tephra frequently being used as a regional chronostratigraphic marker. This eruption event featured several phreatomagmatic and Plinian phases, as well as vent migration and magma chamber collapse, resulting in the formation of a caldera which subsequently filled with groundwater to form a lake. Present-day activity of the Laacher See system is evidenced by degassing vents in the lake and along its shores, emitting CO2 of magmatic origin. Although the Laacher See Eruption has been the topic of many studies in the past, the structure and infill of the caldera has not yet been fully documented. During two surveys at Laacher See in 2019 and 2021, several types of geophysical data were collected to investigate the lake floor and subsurface. High-resolution seismic reflection profiles were acquired with different acoustic sources, using different frequencies. These profiles were used to construct a seismic stratigraphy of the lake's sedimentary infill. Additionally, a multibeam echosounder was used to produce a high-resolution bathymetric map of the lake floor. Our results show two vent-shaped subbasins within the caldera depression, which are mostly filled with acoustically laminated sediment, reaching a thickness of at least 50 m in the northernmost subbasin. Several stratigraphic units can be distinguished, which are not always evenly distributed across the different subbasins, pointing at different phases of basin infill. In the central part of the lake, we identify a large gas accumulation zone through enhanced reflections and acoustic blanking, preventing visualization of the basin infill and structure underneath. Along the slopes of the lake, the lake sediments often contain mass-transport deposits, occurring along at least 9 different stratigraphic horizons. In order to reconstruct the sedimentation history of the lake since the 13 ka BP eruption, a total of 4 sediment cores were taken during coring surveys in 2019 and 2023, with recoveries between ~3.5 and ~8.5 meter below the lake floor. These sediment cores will be integrated with the reflection seismic data to further characterize different phases of sedimentation in the lake. The acquired data shows promising results that will help to reconstruct the sedimentary evolution of Laacher See since its eruption and aid in a better understanding of the caldera formation and structure, and its sedimentary infill history.

Background In July 2021, destructive floods in Western Europe were triggered by enormous precipitation rates related to a low-pressure system named "Bernd." These catastrophic events led not only to major damage to infrastructure, severe economic losses, and the loss of lives but also to significant landscape changes and modifications. Here, we focus, as a case study, on the flood aftermath of the Ahr Valley in Rhineland-Palatinate state in western Germany, as it was one of the most affected and destroyed regions by the flood. We utilize high-resolution Digital Terrain Models (DTMs) based on airborne Light Detection and Ranging (LiDAR) that were taken shortly before and after the flood to investigate insights into geomorphic changes.Results By calculating Digital Terrain Models of Difference (DoD), we are able to quantify volumetric and areal changes caused by erosional and depositional processes for different sites in the Ahr Valley. Due to the morphology of the narrow Ahr Valley, most of the erosion and deposition is located within the deeply incised canyon of the Ahr River. The comprehensive analysis reveals notable morphological modifications throughout the study area, with a calculated erosion/deposition areal ratio of 0.46 and an erosion/deposition volumetric ratio of 0.63. Our findings indicate massive deposition regarding both areal and volumetric. We selected six different locations along the Ahr Valley that showcase distinct aspects of flood-induced fluvial morpho-dynamics. Deposition occurred mainly in point bars and downstream of destroyed artificial levees, in a braided river style.Conclusion Our investigations contribute to an overview and assessment of the morphological response to the destructive flood in the Ahr Valley. The results emphasize the necessity for implementing effective flood management strategies, as most of the urban areas in the Ahr Valley were flooded. Moreover, our results provide valuable insights into the impacted areas, highlighting vulnerable locations for flood-related erosion and deposition. This information could contribute to future mitigation and protection efforts, aiding in the development of comprehensive strategies to minimize the impact of similar events in the future.

Continuous monitoring of volcanic gas emissions is crucial for understanding volcanic activity and potential eruptions. However, emissions of volcanic gases underwater are infrequently studied or quantified. This study explores the potential of Distributed Acoustic Sensing (DAS) technology to monitor underwater volcanic degassing. DAS converts fiber-optic cables into high-resolution vibration recording arrays, providing measurements at unprecedented spatio-temporal resolution. We conducted an experiment at Laacher See volcano in Germany, immersing a fiber-optic cable in the lake and interrogating it with a DAS system. We detected and analyzed numerous acoustic signals that we associated with bubble emissions in different lake areas. Three types of text-book bubbles exhibiting characteristic waveforms are all found from our detections, indicating different nucleation processes and bubble sizes. Using clustering algorithms, we classified bubble events into four distinct clusters based on their temporal and spectral characteristics. The temporal distribution of the events provided insights into the evolution of gas seepage patterns. This technology has the potential to revolutionize underwater degassing monitoring and provide valuable information for studying volcanic processes and estimating gas emissions. Furthermore, DAS can be applied to other applications, such as monitoring underwater carbon capture and storage operations or methane leaks associated with climate change.

In 2013 there were reports on exceptionally deep earthquakes in ca. 40 km depth below the intraplate East Eifel Volcanic Field, Germany. Due to this observation the regional seismological monitoring network was improved to better explore this unusual seismicity. In order to acquire the necessary instruments, financial resources, and man power, a close partnership was initiated between the local state seismological service and academic research institutions. As an outcome the seismological field experiment called Deep Eifel Earthquake Project – Tiefe Eifel Erdbeben (DEEP-TEE) was accomplished which measures high-quality ground motion recordings since 2014. These measurements are used to study deep magmatic processes around the Laacher See Volcano (LSV) which was the site of a paroxysmal eruption just 13,079 years ago. As the DEEP-TEE network is located in a region with a high cultural noise and loose sediments, a careful site selection was a major task. Here, the network design is described and its recordings are used to determine 1-D seismic velocity models (vp, vs, and vp / vs) with station delay times to relocate the seismic events. The models include a priori information from active seismic experiments, especially in the mantle, to overcome resolution problems. The new velocity models allow to (re)locate the local earthquakes with horizontal and vertical uncertainties of ca. 0.5 km and 2.0 km, respectively. A special highlight of DEEP-TEE is the frequent observation of deep low-frequency (< 10 Hz) earthquakes whose hypocentres outline an active translithospheric channel, feeding the magmatic-fluid-volatile system underneath the LSV.

In Italy, the actual geothermal concessions for the use of the geothermal resources expire in 2024. By the forthcoming assignment of the mining rights participate - beyond ENEL-Greenpower - also players of the free market, who intend to apply new technologies, accessing, however, one and the same geothermal reservoirs of Larderello-Travale and Mt. Amiata. The use of different methodologies (partial or complete reinjection), in adjacent areas, requires an advanced monitoring system, capable to locate microseismicity in real-time, calculating the relevant seismic parameters and communicating the results in quasi-real-time to the involved concessions, the competent authorities and the population. Following the initiative of the "Regione Toscana", the role as responsible monitoring agency (SPM) has been assigned to INGV, with the purpose to guarantee a homogeneous and centralized monitoring of all concessions operating in the Tuscan geothermal areas. Concerning power plants under national jurisdiction, the ministerial guidelines propose an experimental alert- and reaction-scheme, for water reinjection, exclusively. In this perspective, it is important to stress the actual lack of specific guidelines for geothermal exploitation on regional level. The aim of the present work is to summarize the experiences collected during the management of geothermal systems in other countries and to promote the drafting of a document that defines an appropriate communication scheme for application of the monitoring tasks by the SPM. Such a scheme may represent the basis for developing a reaction scheme and could be useful for the implementation of future regional monitoring guidelines for geothermal activities.

Persistent microseismicity in the East Eifel Volcanic Field occurs along the Ochtendung Fault Zone (OFZ) just SE of Laacher See Volcano. In addition, deep-low-frequency earthquakes close by are a strong indication for active magmatic processes. No surface expression is known for the OFZ, therefore an active seismic study was conducted in the summer 2021 aiming to detect the near-surface structure of the fault. The survey follows a line nearly perpendicular to the assumed fault orientation. The total length of the survey is 4,500 m with 5 m geophone distance and a maximum offset of 1000 m. Additional to these vertical component geophones, 3-component sensors were deployed at several sites along the profile in order to record far offsets. A drop-weight served as a seismic source. 1,022 shots lead to a total of more than 225,000 channels with maximum offsets of up to 1km, if including the 3-component sensors even up to 5km. Standard QC procedures and the stacking of the single shots at each shot point was done. The data set comprises 177 shot gathers with up to 221 receivers active at the same time. On these data the first onset P-wave arrivals were determined resulting in more than 35000 picks. The refraction tomography uses an innovative inversion technique harnessing the power of a transdimensional, hierachical Markov chain Monte Carlo (McMC) algorithm without the need of a priori assumptions. The number of Voronoi cells describing the Earth structure model and the level of data noise is automatically determined during the inversion process. The forward modelling is performed by a fast, finite-difference based eikonal solver. Starting several hundred McMC-chains across multiple CPU-cores leads to the parallelism needed for efficient sampling of the model space, thus computing of a refraction tomography 2-D Earth structure model including its uncertainty. We achieve a good resolution in depth down to about 200 m throughout our model. The thickness of the tephra layer covering the Rhenish shield is increasing from SW (few meters) to NE (80 m) along the profile. Further studies are still needed to illuminate the shallow structure of the OFZ.

Germany has a long history in seismic instrumentation. The installation of the first station sites was initiated in those regions with seismic activity. Later on, with an increasing need for seismic hazard assessment, seismological state services were established over the course of several decades, using heterogeneous technology. In parallel, scientific research and international cooperation projects triggered the establishment of institutional and nationwide networks and arrays also focusing on topics other than monitoring local or regional areas, such as recording global seismicity or verification of the compliance with the Comprehensive Nuclear-Test-Ban Treaty. At each of the observatories and data centers, an extensive analysis of the recordings is performed providing high-level data products, for example, earthquake catalogs, as a base for supporting state or federal authorities, to inform the public on topics related to seismology, and for information transfer to international institutions. These data products are usually also accessible at websites of the responsible organizations. The establishment of the European Integrated Data Archive (EIDA) led to a consolidation of existing waveform data exchange mechanisms and their definition as standards in Europe, along with a harmonization of the applied data quality assurance procedures. In Germany, the German Regional Seismic Network as national backbone network and the state networks of Saxony, Saxony-Anhalt, Thuringia, and Bavaria spearheaded the national contributions to EIDA. The benefits of EIDA are attracting additional state and university networks, which are about to join the EIDA community now.

Abstract The Quaternary volcanic fields of the Eifel (Rhineland‐Palatinate, Germany) had their last eruptions less than 13,000 years ago. Recently, deep low‐frequency (DLF) earthquakes were detected beneath one of the volcanic fields showing evidence of ongoing magmatic activity in the lower crust and upper mantle. In this work, seismic wide‐ and steep‐angle experiments from 1978/1979 and 1987/1988 are compiled, partially reprocessed and interpreted, together with other data to better determine the location, size, shape, and state of magmatic reservoirs in the Eifel region near the crust‐mantle boundary. We discuss seismic evidence for a low‐velocity gradient layer from 30–36 km depth, which has developed over a large region under all Quaternary volcanic fields of the Rhenish Massif and can be explained by the presence of partial melts. We show that the DLF earthquakes connect the postulated upper mantle reservoir with the upper crust at a depth of about 8 km, directly below one of the youngest phonolitic volcanic centers in the Eifel, where CO2 originating from the mantle is massively outgassing. A bright spot in the West Eifel between 6 and 10 km depth represents a Tertiary magma reservoir and is seen as a model for a differentiated reservoir beneath the young phonolitic center today. We find that the distribution of volcanic fields is controlled by the Variscan lithospheric structures and terrane boundaries as a whole, which is reflected by an offset of the Moho depth, a wedge‐shaped transparent zone in the lower crust and the system of thrusts over about 120 km length.

The occurrence of deep low-frequency (DLF) microearthquakes beneath volcanoes is commonly attributed to mass transport in the volcanic plumbing system and used to infer feeding channels from and into magma reservoirs. The key question is how magmas migrate from depth to the shallow crust and whether magma reservoirs are currently being recharged. For the first time since the improvement of the local seismic networks in the East Eifel region (Rhineland-Palatinate, Germany), we detect and locate recurrent DLF earthquakes in the lower crust and upper mantle beneath the Laacher See Volcano (LSV), using a joint data set of permanent sensors and a temporary deployment. So far, eight DLF earthquake sequences were observed in four distinct clusters between 10 and 40 km depth. These clusters of weak events (M-L< 2) align along an approximately 80. southeast dipping line south of the LSV. Moment tensor solutions of these events have large shear components, and the irregular dispersion and long coda of body waves indicate interaction processes between shear cracks and fluids. We find a rotation of P-axes orientation for shallow tectonic earthquakes compared to DLF events, indicating that the stress field in the depth interval of DLF events might favour a vertical migration of magma or magmatic fluids. The caldera of the LSV was formed by the last major eruption of the East Eifel Volcanic Field only 12.9 kyr ago, fed by a shallow magma chamber at 5-8 km depth and erupting a total magma volume of 6.7 km(3). The observed DLF earthquake activity and continuous volcanic gas emissions around the LSV indicate an active magmatic system, possibly connected with an upper mantle melt zone.