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Sets of marine terraces, sediments, and paleoshorelines are commonly found in forearc regions worldwide. A common assumption holds that crustal uplift prevents these features from littoral erosion. Here, we study the vertical deformation of Karpathos, a forearc island in the eastern Mediterranean, whose long axis extends at a high angle to the strike of the Hellenic Subduction System (HSS). We target three key coastal localities along the island to discuss spatial and temporal variability of vertical motion. We mapped sets of up to 19 marine terraces per locality, with elevations ranging from 1.5 to ∼350 masl. Ages for terraces and sediments are constrained by radiocarbon (<31 masl) and Sr‐isotope (2–310 masl) dating, and range from 2.4 ka to ∼4.3 Ma. Data analysis shows that average uplift rates are up to two orders of magnitude faster over shorter (⪅100 ka) than longer (⪆100 ka) timescales, in agreement with other local and global data sets. Further, we find evidence for multiple marine reoccupations of late Pleistocene terraces, indicating that carbonate beachrock is often resistant to multiple interactions with sea‐level. Neogene marine sequences that witness longer periods (∼4 Ma) show signs of alternating vertical motion. Using this novel data set, we explore the effects of various mechanisms (i.e., upper‐plate normal faulting, splay‐thrust faulting, basal underplating) on the spatial and temporal patterns of vertical deformation. Although the contribution of each mechanism to the net vertical deformation cannot be isolated with certainty, our results show that none alone could account for the observations. Plain Language Summary: In this study, we focus on understanding how the landmass of Karpathos Island, in the Hellenic Subduction System in the Mediterranean Sea, moved vertically over time. We focus mainly on marine terraces, which are wave‐cut platforms near the sea forming staircase‐like topography. The age of these platforms has been constrained by dating fossil shells, shell fragments, and soils that mantle the terraces: for young (closer to the sea‐level) markers we used the isotope Carbon‐14, while for older terraces (further inland) Strontium‐87. We found that the island of Karpathos subsided prior to ∼4.3 Ma, but since then it experiences uplift. From our analysis, we find that the vertical motion of the island is the result of, at least, three interrelated processes: (a) sediment underplating, that scrapes sediments from the down‐going plate during subduction and attaches them to the base of the upper plate, pushing it upwards; (b) large earthquakes that occur either at the interface of two converging plates or on large faults that splay from this interface; and (c) smaller earthquakes produced by the horizontal stretching of the Aegean crust. Key Points: Karpathos provides a natural transect across the Hellenic forearc for exploring vertical deformationNo single mechanism of vertical movement alone can explain the full range of observations and dataUnderplating, splay faulting, and normal faulting interact in space and time to produce overall uplift on Karpathos since ∼4.3 Ma [ABSTRACT FROM AUTHOR]

An interlaboratory comparison (ILC) was organised to characterise 87Sr/86Sr isotope ratios in geological and industrial reference materials by applying the so‐called conventional method for determining 87Sr/86Sr isotope ratios. Four cements (VDZ 100a, VDZ 200a, VDZ 300a, IAG OPC‐1), one limestone (IAG CGL ML‐3) and one slate (IAG OU‐6) reference materials were selected, covering a wide range of naturally occurring Sr isotopic signatures. Thirteen laboratories received aliquots of these six reference materials together with a detailed technical protocol. The consensus values for the six reference materials and their associated measurement uncertainties were obtained by applying a Gaussian, linear mixed effects model fitted to all the measurement results. By combining the consensus values and their uncertainties with an uncertainty contribution for potential heterogeneity, reference values ranging from 0.708134 mol mol‐1 to 0.729778 mol mol‐1 were obtained with relative expanded uncertainties of ≤ 0.007 %. This study represents an ILC on conventional 87Sr/86Sr isotope ratios, within which metrological principles were considered and the compatibility of measurement results obtained by MC‐ICP‐MS and by MC‐TIMS is demonstrated. The materials characterised in this study can be used as reference materials for validation and quality control purposes and to estimate measurement uncertainties in conventional 87Sr/86Sr isotope ratio measurement. [ABSTRACT FROM AUTHOR]