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BackgroundPreservation of fossil vertebrates in volcanic rocks is extremely rare. An articulated skull (cranium and mandible) of a rhinoceros was found in a 9.2±0.1 Ma-old ignimbrite of Cappadocia, Central Turkey. The unusual aspect of the preserved hard tissues of the skull (rough bone surface and brittle dentine) allows suspecting a peri-mortem exposure to a heating source.Methodology/Principal FindingsHere we describe and identify the skull as belonging to the large two-horned rhinocerotine Ceratotherium neumayri, well-known in the late Miocene of the Eastern Mediterranean Province. Gross structural features and microscopic changes of hard tissues (bones and teeth) are then monitored and compared to the results of forensic and archaeological studies and experiments focusing on heating effects, in order to reconstruct the hypothetical peri-mortem conditions. Macroscopic and microscopic structural changes on compact bones (canaliculi and lamellae vanished), as well as partial dentine/cementum disintegration, drastic enamel-dentine disjunctions or microscopic cracks affecting all hard dental tissues (enamel, cementum, and dentine) point to continued exposures to temperatures around 400–450°C. Comparison to other cases of preservation of fossil vertebrates within volcanic rocks points unambiguously to some similarity with the 79 AD Plinian eruption of the Vesuvius, in Italy.Conclusions/SignificanceA 9.2±0.1 Ma-old pyroclastic density current, sourced from the Çardak caldera, likely provoked the instant death of the Karacaşar rhino, before the body of the latter experienced severe dehydration (leading to the wide and sustainable opening of the mouth), was then dismembered within the pyroclastic flow of subaerial origin, the skull being separated from the remnant body and baked under a temperature approximating 400°C, then transported northward, rolled, and trapped in disarray into that pyroclastic flow forming the pinkish Kavak-4 ignimbrite ∼30 km North from the upper Miocene vent.

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This research proposes a suite of volcanic events that took part in the edification of the double-peaked Hasandağ stratovolcano in southern Cappadocia. Inter-correlations of sections dispatched along geographic transects across the volcano evidence continuities/discontinuities and stratigraphic relationships using key layers identified through this process which is, later, framed by a radiometric dating control of some of these formations. The main goal is to provide some chronological markers of the geomorphological evolution of the volcano. The stratigraphy, lithology and facies, the landform definitions and new dates provide information about eruption types and their role in shaping the morphologies of the volcano through time. Recent ages from literature and seven new K/Ar dates contribute in enriching the story of the volcanic activity that built the Hasandağ stratovolcano landforms. The part of the story exposed in this article starts mainly c. 700/650 ka ago with the construction of a Mid-Pleistocene volcano. Later, between 220 and 120 ka ago, main events occurred in the NE part of the volcano. After an initial Plinian eruption, a caldera collapse is recorded by pumice flows. Close to the emission point, a small collapse structure is today filled with a much younger dacite flow. After the Plinian eruption, the partial destruction of a volcano caused one or two avalanches containing several meters-thick distinct blocks that flew north c. 16-18 km over the roof of the Cappadocian Miocene ignimbrites. Remains of the destructed volcano flanks are not visible. Either they are buried below younger lava flows forming the Küçük Hasandağ cone, or a seism in the Tuz Gölü Fault Zone during the avalanche may have resulted in an explosion. This event was followed by extrusion of rhyolitic domes positioned on the caldera rim, emitting pumice falls now filling-in the Güvercin valley stream down to Ihlara village. During Late Pleistocene emission of andesite and dacite flows and domes, accompanied by several pyroclastic flows formed today's terminal cones of the stratovolcano.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Volcanoes have dormancy periods that may last decades to centuries meaning that eruptions at volcanoes with no historical records of eruptions are common. Baseline monitoring to detect the early stages of reawakening is therefore important even in regions with little recent volcanic activity. Satellite techniques, such as InSAR, are ideally suited for routinely surveying large and inaccessible regions, but the large datasets typically require expert interpretation. Here we focus on Turkey where there are 10 Holocene volcanic systems, but no eruptions since 1855 and consequently little ground-based monitoring. We analyse data from the first five years of the European Space Agency Sentinel-1 mission which collects data over Turkey every 6 days on both ascending and descending passes. The high relief edifices of Turkey’s volcanoes cause two challenges: 1) snow cover during the winter months causes a loss of coherence and 2) topographically-correlated atmospheric artefacts could be misinterpreted as deformation. We propose mitigation strategies for both. The raw time series at Hasan Dag volcano shows uplift of ~ 10 cm between September 2017 and July 2018, but atmospheric corrections based on global weather models demonstrate that this is an artefact and reduce the scatter in the data to < 1 cm. We develop two image classification schemes for dealing with the large datasets: one is an easy to follow flowchart designed for non-specialist monitoring staff, and the other is an automated flagging system using a deep learning approach. We apply the deep learning scheme to a dataset of ~ 5000 images over the 10 Turkish volcanoes and find 4 possible signals, all of which are false positives. We conclude that there has been no cm-scale volcano deformation in Turkey in 2015–2020, but further analysis would be required to rule out slower rates of deformation (< 1 cm/yr). This study has demonstrated that InSAR techniques can be used for baseline monitoring in regions with few historical eruptions or little reported deformation.