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The Superstition Hills Fault (SHF) exhibits a rich spectrum of slip modes, including M 6+ earthquakes, afterslip, quasi‐steady creep, and both triggered and spontaneous slow slip events (SSEs). Following 13 years of quiescence, creepmeters recorded 25 mm of slip during 16–19 May 2023. Additional sub‐events brought the total slip to 41 mm. The event nucleated on the northern SHF in early‐May and propagated bi‐laterally at rates on the order of kilometers per day. Surface offsets reveal a bi‐modal slip distribution, with slip on the northern section of the fault being less localized and lower amplitude compared to the southern section. Kinematic slip models confirm systematic variations in the slip distribution along‐strike and with depth and suggest that slip is largely confined to the shallow sedimentary layer. Observations and models of the 2023 SSE bear a strong similarity to previous slip episodes in 1999, 2006, and 2010, suggesting a characteristic behavior. Plain Language Summary: Studying the mechanical properties and behavior of faults is essential for understanding earthquake ruptures. In this study, we investigate a recent slip event on the Superstition Hills Fault (SHF), which has a well‐documented record of slip. A notable aspect of the SHF is that it periodically undergoes "slow slip events" (SSEs), where the fault slips and releases energy without any accompanied ground shaking. During May‐July 2023, the SHF experienced a major SSE for the first time in 13 years. Our analysis shows that it was the largest documented SSE on the SHF and released equivalent energy to a magnitude 4.5 earthquake. We also find that the spatial pattern of fault slip is very similar to several previous slip events in 1999, 2006, and 2010, suggesting that the SHF has a tendency to slip in a characteristic manner. Key Points: We document a recent spontaneous slow slip event (SSE) on the Superstition Hills Fault using creepmeter, Interferometric Synthetic Aperture Radar, Global Navigation Satellite System, and field measurementsOver 41 mm of slip occurred from mid‐May to mid‐July 2023, with moment release corresponding to a Mw 4.5 earthquakeThe kinematics of the 2023 event are remarkably similar to several previous SSEs, suggesting a characteristic rupture process [ABSTRACT FROM AUTHOR]

The Bohemian Forest was glaciated during Pleistocene cold periods. However, opinions on the extent of the glaciation of this mountain range are divided and vary throughout the scientific communities on either side of the Czech/German border. There is the hypothesis of a more extensive glaciation, which is to some extent supported on the Bavarian side, but Czech researchers rather incline to the existence of individual cirques or small valley glaciers. We present the results of geophysical analyses using electrical resistivity tomography carried out in the vicinity of Kleiner Rachelbach cirque. The aim was to examine the extent of the glacial sediments and thus, prove or disprove the hypothesis of a more extensive glaciation. We were seeking to find geophysical manifestations of the glacial sediments (determined on the basis of a literature review, the official geological map and our research) in a moraine complex and beyond it, where long valley glaciers are assumed to have extended. We observed such a manifestation only in the moraine complex. We can thus disprove the hypothesis of an extensive glaciation in the vicinity of Kleiner Rachelbach cirque. [ABSTRACT FROM AUTHOR]

A set of two maar craters (Ztracený rybník and Bažina) was newly identified in Western Bohemia. The two new volcanic geomorphologic features are located on the western uplifted shoulder of the Cheb-Domažlice Graben (Fig. 1). With respect to other small preserved monogenetic volcanoes aligned along the Tachov Fault (Fig. 1), a Pleistocene age has also been ascribed to the two newly found maars. In contrary to the earlier discovered maars (Mrlina et al. 2009, Rohlmüller et al. 2017) which occur and had erupted in the phylites, Ztracený rybník and Bažina maars are confined to granites to granodiorites of the Smrèiny Pluton. The position of the craters in hard rocks results in well-preserved morphology with sharp edges (Fig. 2). The morphology of Ztracený rybník was studied using the digital elevation model based on LiDAR 5th generation data provided by the State Administration of Land Surveying and Cadastre of the Czech Republic (Fig. 2). The electric-resistivity tomography (ERT) and shallow boreholes (6-6.7 m in deep) were employed to study the inner structure, and the uppermost part of the sedimentary infill of the crater (Fig. 3). The ERT data reveal presence of ca 100 m thick sedimentary infill within the crater, under which a diatreme breccia was recognized (Figs 4 and 5). The uppermost part of the sedimentary infill consists of Holocene peat and underlying lacustrine sediments. Radiocarbon dating of organic layer provides the age ~ 45.7 cal kyr BP, indicating the sedimentation to have taken place during the warmer phase of the last pleniglacial (interstadial MIS 3). Nevertheless, this dating is not supported by the palynological results (Tab. 2), suggesting the Early Pleistocene age of the sediment. Ztracený rybník and Bažina maars represent the northernmost occurrences of the Pleistocene volcanism associated with the Cheb- Domažlice Graben. Surprisingly, these two volcanoes located in a granitic pluton originated from maar-forming phreatomagmatic eruptions, whereas nearby Komorní hùrka, located in watersaturated sediments of the Cheb Basin, was formed mainly by dry Strombolian-type eruptions. Ztracený rybník with its sedimentary infill has a great potential for further research since it represents important paleoclimatic archive. Another topic for further investigation appears to be a search for remnants of Ztracený rybník tephra in wider area. [ABSTRACT FROM AUTHOR]

The Zebín Volcano, Czech Republic, is a quarried tuff cone that offers the opportunity to understand emplacement processes responsible for magma transport through a pyroclastic cone and magmatic processes involved in its development. A high‐resolution ground magnetometry survey, electrical resistivity tomography, and refraction seismic were conducted to supplement field mapping of the size, shape, and inner structure of the volcanic system. The Zebín Volcano yields normal polarity rocks, and the cone is underlain by a complex and branching magma feeder system with several diverging dikes. Samples were collected at 24 sites from feeder dikes and the main conduit for anisotropy of magnetic susceptibility and paleomagnetic analysis. Anisotropy of magnetic susceptibility results yield inferred magma flow directions indicating subhorizontal magma flow toward and away from the axial conduit as well as both upward and downward flow. Paleomagnetic data from all sites are normal polarity with statistically distinct remanence directions between some sites that indicate that significant time passed or deformation occurred during the growth of this volcanic system. 40Ar/39Ar isochron ages of groundmass provide emplacement ages of 18.38 ± 0.03 and 18.45 ± 0.03 Ma, whereas a weighted mean date of 18.52 ± 0.03 Ma for hornblende provides an eruption age. We argue that the Zebín Volcano evolved from a polyphase feeding system and through a complex feeder network. This detailed study shows that many monogenetic volcanoes deserve highly detailed study, as their subtleties can provide insight into broader crustal and magmatic environment during magmatism. Key Points: The data from Zebín Volcano reveal that multiple magma conduits were emplaced and the volcano erupted over a protracted period of timePaleomagnetic data show evidence for subvolcanic deformation associated with the growth of the volcanoGeophysical data image the subsurface geometry of the volcanic magma feeder system [ABSTRACT FROM AUTHOR]

The Cyrilka Cave is the second longest pseudokarst cave and the longest crevice-type cave in Czechia. Developed within the headscarp area of a deep-seated landslide, the cave became a focus of scientific research in recent years when new passages were discovered. Structural analysis provided a general tectonic plan of the cave, as well as more detailed data on geometry and kinematics of the relaxed rock massif. The primary structure of NNE- to ENE-striking bedding is broken by a system of NNE-striking fissures interconnected by two continuous ENE-striking dextral fracture zones. Abundant signs of recent sinistral strike-slips within the rock massif represent a bold structural feature of the cave. Along with DEM imaging and a detailed survey of the cave, 2-D and 3-D ERT measurements completed an image of the main predispositions and revealed the internal structure of the slope deformation. These measures also detected unknown crevices above the existing headscarp, which indicate the retrograde evolution of the landslide. Methodologically, we used the 3-D electrical resistivity tomography in the incoherent sedimentary flysch rocks for the first time. Based on radiocarbon dating of the stalactite core, the minimum age of the cave is up to 19,900 ± 280 cal BP, which is the oldest age detected in the area of the Outer Flysch Carpathians so far; we thoroughly discuss further indirect evidence indicating a probable Late Pleistocene age of the cave. [ABSTRACT FROM AUTHOR]