Netherlands Journal of Geosciences

Confirming b-value spatial variations in Groningen gas field using machine-learning-derived seismic data

Laura Gulia — 2026-07-31

The Groningen gas field is Europe’s largest onshore reservoir. Continuous production between 1963 and 2024 has driven reservoir compaction and subsidence, progressively loading pre-existing faults and inducing earthquakes. Recently examined spatio-temporal variations of the Gutenberg–Richter b-value, a proxy for differential stress, across the field, mapping persistent low-b regions in the north and documenting a decade-long trend towards spatial homogeneity closely related to production.

This study revisits Gulia’s results by integrating the original Royal Netherlands Meteorological Institute (RNMI) dataset with the enhanced earthquake catalogue of which newly identifies 660 events and reveals non-clustered and swarm behaviours amongst induced seismicity. The combined/improved catalogue allows to better capture recent trends coinciding with reduced extraction rates and a shift in production towards the south. The aim of this work is to evaluate whether the patterns and hypotheses proposed remain consistent considering the enhanced dataset and to update the analysis with the most recent data. We also evaluate the impact on the evolution of the b-value in the probability of larger events, finding that the continued decrease in b-value compensates for the decrease in seismic activity.

Fault-zone hydraulic conductivity distribution in unconsolidated sediments: insights from a trench study across the Peel Boundary Fault Zone, the Netherlands

Rimbaud E. Lapperre — 2026-06-25

In the subsurface, the faults of the Peel Boundary Fault Zone, part of the Roer Valley Rift System in the Netherlands, Germany, and Belgium, often act as fault-parallel conduits and fault-perpendicular barriers for groundwater flow. However, our understanding of the conduit–barrier architecture of these faults remains limited. This study addresses this gap by presenting a detailed overview of the spatial variation in hydraulic conductivity and anisotropy, based on 161 collected samples, resulting in 150 measurements of saturated hydraulic conductivity (K_sat) and total porosity (P_total), and 151 measurements of median grain size (GS) from a trench site near Uden, the Netherlands. The results indicate that K_sat values across the fault range by almost four orders of magnitude, from 0.004 to 32.1 m day⁻¹. Within this range, the fault exhibits the lowest horizontal (0.01–3.6) and vertical (0.004–7.1) K_sat values. Compared to the fault, values in the foot-wall damage zone (horizontal: 1.4–22.6 and vertical: 0.08–18.4) are significantly higher for both orientations, whereas in the hanging-wall damage zone (horizontal: 2.0–22.7 and vertical: 1.8–9.5), all values are higher, but only the horizontal values reach statistical significance. These findings indicate that the conduit–barrier effect of faults in unconsolidated sediments extends to the near surface. Hydraulic conductivity largely correlates positively with median GS but shows little to no overall correlation with total porosity (P_total). This trench study also reveals that the near-surface conduit–barrier architecture and hydraulic conductivity distribution is likely to evolve over geological timescales due to ongoing hydrogeological processes and fault activity. Such insight has the potential to contribute to future approaches for protecting and restoring fault-related seepage areas known as ‘wijstgronden’.

Human-induced lowland floodplain transformation from peat- to clastic-dominated during the early modern period

Teun van den Putte — 2026-05-28

Many stream valleys in Northwestern Europe were once peat-filled during the Holocene. Nonetheless, they are often not considered as peat valleys in restoration projects, as they are now covered by thick clastic deposits. This sediment influx is often attributed to past deforestation and intensification of agriculture on adjacent hill slopes. However, this explanation fails in lowlands such as the Netherlands. How the clastic material formed in those stream valleys is still unclear. This study aims to determine the origin of thick humic sand covers in formerly peat-rich stream valleys. Two stream valleys in the sandy southern Netherlands were studied, the Keersop and the Kleine Dommel. The formation of the humic sand covers was studied by mapping the soils and subsurface lithology, luminescence dating and a review of archaeological and historical information. Our interdisciplinary research design has revealed direct human controls on historical floodplain transformations from peat-dominated to clastic-dominated in both valleys. The results show that the humic sand covers display many similarities with other Plaggic Anthrosols in the region, which developed after fertilisation of arable lands since the Middle Ages. Both contain humic sand, traces of charcoal and ceramics, and both can contain light-coloured sand inclusions. Our datings show the soils in the Kleine Dommel valley were anthropogenically raised during the late 17th or early 18th centuries. We argue that artificial raising of stream valleys with sands was a common practice in the southern Netherlands, intended to support agriculture on the existing peaty soils by improving their bearing capacity and drainage. This identified human-induced lowland floodplain transformation from peat-dominated to clastic-dominated underlines that these past human alterations should be considered when restoring stream valley ecosystems.

Causes of uncertainty in geomodelling inputs: data review of Paleozoic geology in the Euregion Meuse-Rhine

Jasper Maars — 2026-05-18

Geological models are important for subsurface engineering and it is crucial to identify their uncertainties. However, uncertainties in their geological input can be elusive and easily overlooked. Through a data review of Paleozoic geology of the Euregion-Meuse-Rhine, uncertainties in geomodelling inputs are identified and their causes are categorised into four groups: (1) stratigraphic interpretation, (2) fault interpretation, (3) transferring data, and (4) uncertainty in legacy materials. Examining these uncertainties reveals numerous sources for them that are intertwined. The number of connected sources of uncertainty demonstrate that the uncertainty chain in geomodelling is complex, calling for further investigation into the magnitude of the identified uncertainties.

The Paleozoic geology in the study region has structural complexity in which geomodelling is hampered by limited outcrops and scattered input data. We compile input and examine data inconsistencies by collecting legacy literature and maps, conducting fieldwork, and compiling a dataset of 738 boreholes. Stratigraphic profiles of new boreholes (Cottessen-01, Banholt-01, and Terziet-02) are also included and two boreholes (Kastanjelaan-02 and RWTH-01) are re-evaluated with additional palynological constraints. Differences are found between various stratigraphic profiles for the latter two boreholes among different sources and updated stratigraphic profiles are presented for them. Comparing a newly drilled borehole with an existing geological cross-section reveals a >1 km depth mismatch between stratigraphic stages. Comparing stratigraphy of the borehole dataset with different geological maps reveals various degrees of agreement. The identified inconsistencies demonstrate the necessity of validating input data before embarking on any geomodelling exercise.

Geomechanical analysis of subsidence-induced sinkholes and drempels from longwall coal mining using the material point method: A case study from South-Limburg, the Netherlands

J.L. Gonzalez Acosta — 2026-05-11

Subsidence-induced surface instabilities, such as vertical sharp steps in the topography (known as ‘drempels’ in Dutch), subsidence, and sinkholes, can severely impact infrastructure and public safety. These surface displacements features have been observed during and immediately after coal mining in the South Limburg province of the Netherlands. In this study, a numerical framework for modelling large deformation processes, namely the material point method (MPM), is applied to investigate the underlying mechanisms driving the formation of these complex surface features during coal seam excavation. The modelling of this study focuses on a case study from Heerlen, South Limburg, where a shopping centre in the ’t Loon area partially collapsed due to the development of a sinkhole. Different seam configurations and excavation procedures are tested to assess their influence on the magnitude and spatial distribution of ground deformation. The MPM simulations demonstrate a clear connection between the observed deformation patterns and the early longwall mining processes. Modelled stress and strain concentrations coincide with the observed locations of both drempels and the sinkhole at the ground surface. Furthermore, additional insights were obtained. For example, the direction of seam excavation was found to contribute significantly to the overall distribution of deformations, with larger deformations occurring near the starting position and decreasing towards the end excavation. In contrast, reducing the seam dip angle further amplified the deformations, regardless of the excavation direction, with horizontal seams producing more pronounced effects. These behaviours arise in the absence of geological heterogeneities, indicating that operational configuration alone can predispose sites to the development of surface anomalies. This set of results demonstrates that specific mining and excavation configurations can trigger distinct surface deformation features at predictable locations. The study highlights the potential of MPM to capture the complex mechanisms driving mine collapse and ground subsidence, offering both improved understanding and a means to identify vulnerable areas for post-mining geohazard assessment based on subsurface configurations.

Ranzania tenneyorum (Weems, 1985) and Mola pileata (Van Beneden, 1881) (Molidae, Tetraodontiformes): highly specialised fishes from the Breda and Oosterhout formations at Mill-Langenboom, the Netherlands

Femke A. van der Sterren — 2026-04-06

Research into faunal assemblages from the Upper Miocene and Lower Pliocene at Mill-Langenboom, province of Noord-Brabant, the Netherlands, has led to the recognition of premaxillary and dentary beaks of molid fishes (Molidae, Tetraodontiformes). These ex-situ finds, originating either from the Breda Formation or Oosterhout Formation, or both, are here assigned to two extinct taxa, namely, Ranzania tenneyorum and Mola pileata. Mola pileata has previously been recorded from the Middle Miocene of Belgium, the Netherlands, and the United States of America, while R. tenneyorum was up to now known only from the Lower-Middle Miocene Calvert Formation in Virginia (US). The present record thus extends the known geographical and stratigraphical ranges of R. tenneyorum to north-west Europe and the Middle-Miocene – Lower Pliocene.

From lake to river. The Weichselian Lateglacial and early Holocene palaeoenvironmental development of the Moervaart region (northwestern Belgium): a synthesis on vegetation patterns, climate, abiotic landscape and human occupation

Hanneke Bos — 2026-03-16

In this paper, a synthesis is given of a large multi-disciplinary project, which included physical, botanical, zoological and archaeological studies, accelerator mass spectrometer (AMS) ¹⁴C and Optical Stimulated Luminescence (OSL) dating and chemical analyses from numerous locations in and along the extensive Moervaart palaeolake (NW Belgium), south of the Maldegem-Stekene Coversand Ridge. This rich dataset enabled a detailed reconstruction of climate, vegetation development and human presence in the period from the Weichselian Lateglacial and early Holocene. In addition, this dataset was used to make spatial reconstructions of the vegetation patterns in the direct surroundings of the Moervaart palaeolake for seven time slices and artist impressions for three moments in the archaeological record. These vegetation maps and the high resolution data on climate and the abiotic landscape are compared to former human occupation patterns to give insight in these early human presences in NW Europe.

The first evidence for human presence, after a long period of absence, was found from the Allerød period. During this period, hunter-gatherers of the Federmesser culture were present in encampments along the northern shore of the Moervaart palaeolake which had developed during the Bølling period. Both the improving climate and the availability of a fresh water source stimulated human presence. The vegetation transitioned from a tundra landscape in the Bølling period to a boreal forest with birch and pine in the Allerød. During the following cold period of the Younger Dryas, forests retreated and tundra vegetation redeveloped. At the same time, the Moervaart palaeolake and most of the surrounding dune ponds turned dry. Evidence of human presence in the region during the Younger Dryas period is scarce, presumably related to the colder climatic conditions and the strongly reduced availability of fresh water sources. Due to climate warming during the early Holocene, boreal forests expanded again. However, evidence of human occupation of the area remains scarce. The Preboreal forest expansion was shortly interrupted by another cold reversal, the so-called Preboreal Oscillation or 11.4 event. After this event, hunter-gatherers returned to the area, then settling preferably along the dry banks of the Kale/Durme river, a tributary of the Scheldt river, which was the only source of fresh water in the region. During the following Boreal, coniferous forests were gradually replaced by deciduous forests which had developed initially with hazel, elm and oak, but later (Atlantic) also with lime, alder and ash. Hunter-gatherer site-density was highest during the first part of the Boreal, when hazel dominated the landscape. Afterwards, site-density dropped considerably; however, it is not clear whether this reflects a marked population reduction or rather points to changing mobility in response to a changing environment.