Northern Promontory of AdriaArray: Network Design and Realization

AdriaArray is a multinational initiative to cover the Adriatic Plate and its tectonically active surroundings – including units of Adriatic origin – with a dense regional array of seismic stations. AdriaArray provides data for imaging of the crustal and upper mantle structure and for the analysis of seismic activity and hazard. It will help to understand the causes of active tectonics and volcanic fields in the region. The network consists of 1092 permanent and 436 temporary broadband stations from 23 mobile pools. A homogeneous coverage of broadband stations is achieved in an area from the Massif Central in the west to the Carpathians in the east, from the Alps in the north to the Calabrian Arc and mainland Greece in the south. The backbone network (2022‑2026) is complemented by locally densified broadband deployments in the western Carpathians, along the Dubrovnik fault and in the Vrancea region. Data recorded by AdriaArray stations is transmitted in real-time to 12 nodes of the European Integrated Data Archive (EIDA) where it is accessible as a single virtual network. Regular availability and quality checks ensure high data usability. AdriaArray, the largest passive seismic experiment in Europe to date, is based on the cooperation between local network operators, mobile pool providers, technicians, engineers, field teams, researchers, students, and organizations such as ORFEUS (Observatories and Research Facilities for European Seismology) and EPOS (European Plate Observing System). The AdriaArray Seismology Group, founded in 2022, encompasses 64 institutions from 30 countries with 451 participants. Initial Collaborative Research Groups have been established to coordinate data analysis and scientific research. We present the evolution of the experiment and its objectives, describe its preparation and planning, and show maps of the AdriaArray Seismic Network, station properties and coverage. We further describe the data archiving and distribution, list the participating institutions, individuals and networks and discuss collaborative research topics.

Recent receiver function results from a passive seismic experiment have provided new insights into the geodynamic evolution of the Western Carpathians, the eastern extension of the Alps, formed in part by the closure of the Alpine Tethys. The Pieniny Klippen Belt (PKB) represents this closure at the surface, characterised by a narrow, elongated geometry dividing the external fold-and-thrust belt of the Outer Western Carpathians and the Central Western Carpathians. Unlike typical sutures, the PKB lacks ophiolites or high-pressure metamorphic rocks, instead it consists of resistant limestone blocks within a matrix of non-resistant flysch deposits, forming a distinctive “block-in-matrix” structure. This configuration has traditionally been attributed to the hypothesized Czorsztyn ridge, an island-like feature within the Alpine Tethys, where limestone deposition has been thought to occur. The ridge is supposed to correspond to the Briançonnais unit in the Alps, though evidence for its existence remains tenuous.The current passive seismic experiment seeks to validate or refute the Czorsztyn ridge hypothesis. In May 2023, 18 broadband seismic stations were deployed along a north-south trending profile, under the umbrella of the Adria Array, complemented by 9 other permanent and temporary stations. This 27-station dense network enabled the extraction of receiver functions and the creation of Common Conversion Point (CCP) stack images to resolve the sub-surface geometry of the region.Preliminary findings challenge the Czorsztyn ridge model. No distinct continental crustal body – interpretable as the Czorsztyn ridge basement and separate from the northern European platform or ALPCAPA – is evident beneath the PKB. Instead, subsurface structures appear complex, showing similarity to those in the Vienna Basin, located between the Eastern Alps and the Western Carpathians. A blind detachment fault occurs in the deep basement of the Outer Western Carpathians and connects southward with mid-crustal detachments in the Central Western Carpathians. Furthermore, a 40 km wide gap in Moho signature of the receiver functions beneath the PKB may reflect the position of the suture at a lower crustal level. Additionally, the Steimberg Fault in the Vienna basin likely correlates with the PKB, as both exhibit a displacement with partly strike-slip kinematics. Continued data collection and analysis will refine these interpretations and advance the understanding of the tectonic evolution of Western Carpathians.

This volume of 30 chapters authored by 107 geologists and geophysicists from Austria, Czech Republic, Hungary, Poland, Romania, Slovakia, Ukraine, United Kingdom, and the USA provides a comprehensive and understandable account of geology and hydrocarbon resources of the entire Carpathian system from northeastern Austria to southern Romania, including the Neogene foredeep, the foreland platform both in front and beneath the thrust belt, the Carpathian thrust belt, and the late and post orogenic intermontane basins. Principal chapters on regional geology are supplemented by thematic contributions on geodynamic reconstructions, regional geophysical investigations, hydrocarbon systems, and case studies of major oil and gas fields. To date, close to 7 billion barrels of oil and more than 53 trillion cubic feet of natural gas have been produced from the entire Carpathian system. Additional new reserves may be found, especially at deeper structural levels below the Neogene foredeep and the thin-skinned Carpathian thrust belt. Seventeen chapters of Memoir 84 have been printed in full. The remaining chapters have been printed as abstracts only, with the full paper for all 30 chapters as .pdf files on the CD-ROM in the back of this publication. The publication is intended as a source of information to schools, governmental and private institutions, oil companies, and potential investors.

<p>At 01:36 UTC (03:36 local time) on August 24th 2016, an earthquake Mw 6.0 struck an extensive sector of the central Apennines (coordinates: latitude 42.70° N, longitude 13.23° E, 8.0 km depth). The earthquake caused about 300 casualties and severe damage to the historical buildings and economic activity in an area located near the borders of the Umbria, Lazio, Abruzzo and Marche regions. The Istituto Nazionale di Geofisica e Vulcanologia (INGV) located in few minutes the hypocenter near Accumoli, a small town in the province of Rieti. In the hours after the quake, dozens of events were recorded by the National Seismic Network (Rete Sismica Nazionale, RSN) of the INGV, many of which had a ML > 3.0. The density and coverage of the RSN in the epicentral area meant the epicenter and magnitude of the main event and subsequent shocks that followed it in the early hours of the seismic sequence were well constrained. However, in order to better constrain the localizations of the aftershock hypocenters, especially the depths, a denser seismic monitoring network was needed. Just after the mainshock, SISMIKO, the coordinating body of the emergency seismic network at INGV, was activated in order to install a temporary seismic network integrated with the existing permanent network in the epicentral area. From August the 24th to the 30th, SISMIKO deployed eighteen seismic stations, generally six components (equipped with both velocimeter and accelerometer), with thirteen of the seismic station transmitting in real-time to the INGV seismic monitoring room in Rome. The design and geometry of the temporary network was decided in consolation with other groups who were deploying seismic stations in the region, namely EMERSITO (a group studying site-effects), and the emergency Italian strong motion network (RAN) managed by the National Civil Protection Department (DPC). Further 25 BB temporary seismic stations were deployed by colleagues of the British Geological Survey (BGS) and the School of Geosciences, University of Edinburgh in collaboration with INGV. All data acquired from SISMIKO stations, are quickly available at the European Integrated Data Archive (EIDA). The data acquired by the SISMIKO stations were included in the preliminary analysis that was performed by the Bollettino Sismico Italiano (BSI), the Centro Nazionale Terremoti (CNT) staff working in Ancona, and the INGV-MI, described below.</p>

The monitoring of earthquakes and underground explosions worldwide is performed using networks of seismic stations. The vast majority of these stations consist of three mutually orthogonal sensors, one vertical and two horizontal, at a single site. Seismic signals are detected on individual stations, and events are then defined and located by associating the signals recorded on many different stations. Some networks are global (e.g., Romanowicz and Giardini, 2001; Ammon et al. , 2010), and there are increasingly many national and regional networks that, with increasing available computational power and decreasing data transmission and storage costs, are continually becoming denser. This is particularly the case for highly populated regions with significant and destructive seismicity, such as Japan (e.g., Okada et al. , 2004). Networks such as the USArray (Levander et al. , 1999) and GLISN (Clinton et al. , 2014) can comprise both permanent and temporary stations, covering vast regions (usually over a limited time span) to glean information about structure and geophysical processes. It is, however, still the case that large regions of Earth have very poor coverage of permanent seismic stations. Seismic arrays are a special class of seismic station consisting of seismometers at numerous closely spaced sites (usually within an aperture of a few kilometers) such that signal detection and parameter estimation are greatly enhanced by coherently processing the waveforms at the different sites. Progress in seismic array technology was driven largely by the need to monitor underground nuclear weapons testing (e.g., Douglas, 2002), because the events being monitored by any one country were taking place in the territory of another country and it became imperative to be able to detect and correctly identify a weak seismic signal generated by a remote explosion. With the opening for signing of the Comprehensive Nuclear‐Test‐Ban Treaty (CTBT) in 1996 (Dahlman et al. , 2009, …

Even if the Czech Republic occupies a small area in Central Europe, it is unique by the very interesting and varied geological and tectonic development that is recorded in the structure of the present-day Earth’s crust, especially in the case of the Bohemian Massif. The Bohemian Massif can be interpreted as a heterogeneous unit composed of four separate regional domains. Each of them is defined especially by a specific stratigraphic content, tectomagmatic development and tectonic limitation in relation to its surroundings. The history of its development involves a long time period from the Paleoproterozoic to the recent period, i.e. about 2.1 × 109 years. Basic features of the Earth’s crust structure, reflecting in geological maps, were however impressed on the area of the country only by relatively younger phases of Variscan orogeny and, to a lesser extent, Alpine orogeny that affected the eastern part of the country—the Western Carpathians. At the beginning of the Westphalian, the Bohemian Massif became part of the stabilised Variscan crust of the West European Platform, which in consequence meant that it began to act as a single unit, in which any mutual lateral displacement of units, metamorphosis and associated ductile deformation took place no longer. The Western Carpathians are one of partial branches of the vast orogenic belt of the Alpides created from the former Tethys Ocean. The development of the Western Carpathians already begins shortly after terminating the Variscan orogeny. At present, the Carpathians are divided from south to north into the Inner, Central and Outer Western Carpathians. The Central as well as the Inner Carpathians do not occur in the territory of the Czech Republic. The younger accretionary complex in the area of Moravia and Silesia is composed of the Pouzdřany, Ždanice, Subsilesian, Silesian and Fore-Magura Units.

Mantle fabric of western Bohemian Massif (central Europe) constrained by 3D seismic P and S anisotropy

Our paper presents the general overview of the current geophysical results, which helps to improve the geophysical image and the lithospheric structure of the Carpathian-Pannonian Basin region. Two different geophysical methods have been applied for the study of the structure and composition of the lithosphere as well as for determination of the lithospheric thermal structure. Firstly, integrated 2D modeling of gravity, geoid, topography and surface heat flow data was performed. Secondly, based on the results of the CELEBRATION 2000 seismic experiment, a large-scale 3D lithospheric gravity model was developed. The resulting map of the lithospheric thickness shows important variations in lithospheric thickness across the chain as well as along strike of the Carpathian arc. The sediment stripped gravity map is characterized by minima in the Eastern Alps and Western Carpathians. The maxima are observed in the Pannonian Back-arc Basin system, Bohemian Massif, Fore-Sudetic Monocline, Bruno-Silesian unit (BSU), Lublin Trough and partly in the Holy Cross Mts. and Malopolska unit. The Western Carpathian gravity minimum is a result of the interference of two main gravity effects. The first one comes from the low-density sediments of the Outer Western Carpathians and Carpathian Foredeep. The second one is due to the thick low-density upper and middle crust, reaching up to 25 km. The sediment stripped anomaly in the Pannonian Back-arc Basin system is characterized by gravity high that is a result of the gravity effect of the anomalously shallow Moho. The most dominant feature of the complete stripped gravity map is the abrupt change of the positive anomalies along the Pieniny Klippen Belt zone. The complete residual anomaly of the Pannonian Back-arc Basin system and the Western Carpathian orogen is characterized by a long-wavelength gravity low. The lowest values are associated with the thick low-density upper and middle crust of the Inner Western Carpathians. The European Platform is characterized by significantly denser crust with respect to the less dense crust of the microplates ALCAPA and Tisza-Dacia. That is why we suggest that the European platform represents consolidated, while the Carpathian-Pannonian Basin region un-consolidated crust.

The 2012 Emilia seismic sequence (Northern Italy): Imaging the thrust fault system by accurate aftershock location

Seismological monitoring is vital for both fundamental research and applied geophysics. Even in regions with moderate seismicity, a robust seismic network is crucial for hazard assessment and geoscientific advancements. In Ukraine, this need has intensified due to the ongoing recovery and modernization following the war. Ukraine’s seismic network has historically faced significant challenges, including outdated equipment and minimal upgrades since independence. The war exacerbated these issues, resulting in funding cuts, damaged infrastructure, and a loss of expertise.The seismic network operated by the Subbotin Institute of Geophysics of the National Academy of Sciences of Ukraine is currently undergoing reconstruction and modernization. Recent international collaborations have facilitated initial steps toward modernizing the network, particularly in the Carpathian region and beyond.Efforts to reorganize the seismic network in the Carpathian region were supported by the ORFEUS Data Integration Grant under the Geo-INQUIRE Project, with contributions from GFZ German Research Centre for Geosciences, Gaia Code, and Geoazur, which provided instruments and technical support. These initiatives led to the deployment of four new seismic stations at existing, registered sites in September and December 2024, with one additional station planned for early 2025. For the first time, data from the Institute of Geophysics’ seismic network were integrated into the European Integrated Data Archive (EIDA), marking a significant milestone in improving data accessibility and collaboration within the European seismological community.Subbotin Institute of Geophysics is also leading the "Seismic Network Expansion in Ukraine" project, supported by the U.S. Department of Energy (DOE), Lawrence Livermore National Laboratory (LLNL), Michigan State University (MSU), and the EarthScope Consortium. This initiative focuses on deploying new seismic stations and ensuring real-time transmission of high-quality data. Noise surveys were conducted across the Carpathian region, central, and southern Ukraine to identify optimal station sites, considering both natural and anthropogenic noise. As part of this project, the posthole seismic station was installed at the LUBU (Liubeshka) site in December 2024, with additional stations planned, network code UT. Data from these stations are transmitted to the EarthScope Data Management Center.Beyond network modernization, efforts have also focused on education and capacity building. With support from Section 4.7 (GFZ), an educational seismic network using Raspberry Shake seismometers was established. This initiative engages middle and high school students in hands-on seismological research. Educational materials, including a lectures on seismic instruments and a Jupyter Notebook with Python examples, empower students to analyze real-time seismic data. Many students have developed independent research projects, participating in the Junior Academy of Sciences of Ukraine. These activities not only foster scientific curiosity but also highlight the importance of geophysics as a career path.Institute of Geophysics acknowledges funding support from the Data Integration Grant (ORFEUS, Geo-INQUIRE, Grant Agreement 101058518). Instruments and technical support were provided by GFZ, GIPP-GEOFON, GaiaCode, and Geoazur. T. Amashukeli is supported by the MSCA4Ukraine program. SNEMU project is implemented in partnership with Science and Technology Center of Ukraine, U.S. Department of Energy, Lawrence Livermore National Laboratory (USA), Michigan State University (USA), and EarthScope Consortium (USA).

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.

Pilosella officinarum (syn. Hieracium pilosella) is a highly structured species with respect to the ploidy level, with obvious cytogeographic trends. Previous non-collated data indicated a possible differentiation in the frequency of particular ploidy levels in the Czech Republic and Slovakia. Therefore, detailed sampling and ploidy level analyses were assessed to reveal a boundary of common occurrence of tetraploids on one hand and higher ploids on the other. For a better understanding of cytogeographic differentiation of P. officinarum in central Europe, a search was made for a general cytogeographic pattern in Europe based on published data. DNA-ploidy level and/or chromosome number were identified for 1059 plants using flow cytometry and/or chromosome counting on root meristem preparations. Samples were collected from 336 localities in the Czech Republic, Slovakia and north-eastern Hungary. In addition, ploidy levels were determined for plants from 18 localities in Bulgaria, Georgia, Ireland, Italy, Romania and Ukraine. Four ploidy levels were found in the studied area with a contrasting pattern of distribution. The most widespread cytotype in the western part of the Czech Republic is tetraploid (4x) reproducing sexually, while the apomictic pentaploids and mostly apomictic hexaploids (5x and 6x, respectively) clearly prevail in Slovakia and the eastern part of the Czech Republic. The boundary between common occurrence of tetraploids and higher ploids is very obvious and represents the geomorphologic boundary between the Bohemian Massif and the Western Carpathians with the adjacent part of Pannonia. Mixed populations consisting of two different ploidy levels were recorded in nearly 11% of localities. A statistically significant difference in a vertical distribution of penta- and hexaploids was observed in the Western Carpathians and the adjacent Pannonian Plain. Hexaploid populations tend to occur at lower elevations (usually below 500 m), while the pentaploid level is more or less evenly distributed up to 1000 m a.s.l. For the first time the heptaploid level (7x) was found on one site in Slovakia. In Europe, the sexual tetraploid level has clearly a sub-Atlantic character of distribution. The plants of higher ploidy level (penta- and hexa-) with mostly apomictic reproduction prevail in the northern part of Scandinavia and the British Isles, the Alps and the Western Carpathians with the adjacent part of Pannonia. A detailed overview of published data shows that extremely rare records on existence of diploid populations in the south-west Alps are with high probability erroneous and most probably refer to the closely related diploid species P. peleteriana. The recent distribution of P. officinarum in Europe is complex and probably reflects the climatic changes during the Pleistocene and consequent postglacial migrations. Probably both penta- and hexaploids arose independently in central Europe (Alps and Carpathian Mountains) and in northern Europe (Scandinavia, Great Britain, Ireland), where the apomictic plants colonized deglaciated areas. We suggest that P. officinarum is in fact an amphidiploid species with a basic tetraploid level, which probably originated from hybridizations of diploid taxa from the section Pilosellina.

The creation of the Kamchatka regional network of seismic stations began in 1961. The number of stations over the past 60 years has gradually increased and by 2022 the Kamchatka regional network of seismic stations consisted of 88 stations. Data from all seismic stations are available in digital form and provide continuous observations of the seismicity of the Kamchatka region, the fulfillment of tasks within the framework of the Urgent Seismic Reporting Service and the Tsunami Warning Service, seismic monitoring of volcanoes in order to predict eruptions and control their condition. All stations operate independently. The article presents a brief overview of the main studies and summarizes the experience in the field of seismometry and the operation of a network of seismic stations. A description of the equipment of seismic stations is given, a technique for calibrating seismometric channels is briefly considered, issues of synchronization of records of seismic traces and dynamic characteristics of seismic instruments are touched upon, work on studying the properties of the soil stratum at the base of the station pedestal is noted. Some technical aspects of the use of the CM3 seismometer at radio telemetric seismic stations are outlined.

QuestionMosses are important ecosystem engineers in mires. Their pH optima and tolerances presented in the literature differ between regions, even though the high dispersal ability of mosses should prevent local adaptations. Nutrient availability is sometimes suggested as a reason for local niche differentiation. Are patterns in moss niche diversification, optima and tolerance with respect to pH consistent between regions differing in nutrient availability and abundance of calcareous bedrock?LocationWestern Carpathians (Slovakia, a predominantly calcareous P‐ and K‐poor region), Bohemian Massif (Czech Republic, a predominantly crystalline, P‐ and K‐rich region).MethodsAnalyses of an original stratified data set and a large database using species response curves.ResultsAlthough the above two regions differ in abundance of calcareous fens, species pH optima (either original or adjusted according to calcium level) were consistent between the regions and data sets. Calcium‐tolerant peat mosses (Sphagnum warnstorfii, S. contortum, S. teres) showed an optimum at pH 6 and rather narrow niches. Sphagnum fallax was the most acidophilous, and both S. palustre and S. flexuosum had rather wide intermediate niches. The pH amplitudes were largely consistent between the regions (especially when adjusted pH was used), but S. fallax and Aulacomnium palustre exhibited wider niches in the Bohemian Massif. Despite no significant difference in niche optimum and width, some more nutrient demanding and more generalist species occurred at higher frequency in specific parts of the pH gradient in the Bohemian Massif, while some fen specialists showed the opposite pattern.ConclusionsThe small stratified data set and the database data set yielded rather consistent results regarding fen moss niches in the Bohemian Massif and the Western Carpathians. The consistency in pH niches corresponds to the lack of large‐scale genetic differentiation in moss species. The observed inter‐regional differences in species response curves may thus reflect an increased frequency of competitively strong species in certain parts of the pH/Ca gradient in the nutrient‐richer Bohemian Massif rather than genetically conditioned niche shifts. Expansion of these species was probably triggered by potassium enrichment that took place in the 1970s–1980s. Inter‐regional differences in species response curves were observed in both data sets, but in the large database data set they were more frequently statistically significant.

<p><span><span>The current knowledge of the structure of the Bohemian Massif (BM) crust is mostly based on interpretation of refraction and reflection seismic experiments performed along 2D profiles. The recent development of ambient noise tomography, in combination with dense networks of permanent seismic stations and arrays of passive seismic experiments, provides unique opportunity to build the high-resolution 3D velocity model of the BM crust from long sequences of ambient seismic noise data.</span></span></p><p><span><span>The new 3D shear-wave velocity model is built from surface-wave group-velocity dispersion measurements derived from ambient seismic noise cross-correlations by conventional two-step inversion approach. First, the 2D fast marching travel time tomography is applied to regularise velocity dispersions. Second, the stochastic inversion is applied to compute 1D shear-wave velocity profiles beneath each location of the processing grid.</span></span></p><p><span><span>We processed continuous waveform data from 404 seismic stations (permanent and temporary stations of passive experiments BOHEMA I-IV, PASSEQ, EGER RIFT, ALPARRAY-EASI and ALPARRAY-AASN) in a broader region of the BM (in an area of 46-54</span></span><sup><span><span>0 </span></span></sup><span><span>N 7-21</span></span><sup><span><span>0 </span></span></sup><span><span>E). The overlapping period of each possible station-pair and cross-correlation quality review resulted in more than 21,000 dispersion curves, which further served as an input for surface-wave inversion </span></span><span><span>at h</span></span><span><span>igh-density grid with the cell size of 22 km. </span></span></p><p><span><span>We present the new high-resolution 3D shear-wave velocity model of the BM crust and uppermost mantle with preliminary tectonic interpretations. We compare this model with a compiled P-wave velocity model from the 2D seismic refraction and wide-angle reflection experiments and with the crustal thickness (Moho depth) extracted from P-wave receiver functions (see Kampfová Exnerová et al., EGU2020_SM4.3). 1D velocity profiles resulting from the stochastic inversions exhibit regional variations, which are characteristic for individual units of the BM. Velocities within the upper crust of the BM are ~0.2 km/s higher than those in its surroundings. The highest crustal velocities occur in its southern part (Moldanubian unit). The velocity model confirms, in accord with results from receiver functions and other seismic studies, a relatively thin crust in the Saxothuringian unit, whilst thickness of the Moldanubian crust is at least 36 km in its central and southern parts. The most distinct interface with a velocity inversion at the depth of about 20 to 25 km occurs in the Moldanubian unit. The velocity decrease in the lower crust reflects probably its transversely isotropic structure.</span></span></p>