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International Ocean Discovery Program Expedition 401 recovered 983 m of sediment from Portugal’s southwest margin in the northeast Atlantic Ocean at Site U1609 (37°22.6259′ N, 9°35.9120′ W; 1659.5 m water depth). This site was designed to recover the distal contourites deposited by the Mediterranean Overflow Water contour current from the late Miocene to the Pleistocene. We report semiquantitative elemental results from X-ray fluorescence scanning of sediment cores from Site U1609 (Holes U1609A and U1609B) scanned at a 4–5 cm resolution from ~202 to 509 m core depth below seafloor, Method A, equivalent to ~4.52 to ~7.8 Ma. Raw element intensities (in counts per second) for Al, Si, Ca, Ti, Mn, Fe, Rb, Sr, Zr, and Ba are presented here and correlated with lithofacies variations. We also identify biogenic-terrestrial input proportions and illustrate downcore cyclicity and correlation patterns between terrigenous components (Al, Si, Ti, Mn, and Ba), as well as their anticorrelations with biogenic (Ca and Sr) inputs. The cyclical variations in elemental ratios may help stratigraphic correlation between Holes U1609A and U1609B, astronomical tuning of the spliced record, and sedimentary interpretations of changes to the Mediterranean–Atlantic gateway and the bottom current circulation along the Atlantic margin of Portugal before, during, and after the Messinian Salinity Crisis. 

The extremely large slip that occurred on the shallow portion of the Japan Trench subduction zone during the 2011 Mw 9.1 Tohoku-oki earthquake directly contributed to the devastating tsunami that inundated the Pacific coast of Japan. International Ocean Discovery Program (IODP) Expedition 405 (Tracking Tsunamigenic Slip Across the Japan Trench) aimed to investigate the conditions and processes that facilitated the extremely shallow slip on the subduction interface during the 2011 Tohoku-oki earthquake to improve understanding of the factors that allow slip to the trench on subduction zones. Expedition 405 implemented a combined logging, coring, and observatory operational plan at two sites: Site C0026, ~8 km seaward of the Japan Trench, to characterize the input sediments to the subduction zone and Site C0019, ~6 km landward of the trench, where the plate boundary fault zone is present at ~825 meters below seafloor (mbsf). At Site C0026, the input section was logged to ~430 mbsf with a logging-while-drilling (LWD) assembly that characterized the succession of sediments and rocks from the seafloor to the basaltic rocks of the oceanic crust. Cores recovered from four holes as deep as 290 mbsf contain a sequence of hemipelagic and pelagic sediments that will be input into the shallow subduction system and therefore control both the localization of the plate boundary fault zone and the slip behavior of the plate boundary. Site C0019 was previously drilled in 2012 during Integrated Ocean Drilling Program Expedition 343 (Japan Trench Fast Drilling Project [JFAST]), and revisiting this site allowed temporal variations in the frontal prism and plate boundary fault zone to be evaluated. The LWD data to ~980 mbsf characterized the frontal prism, plate boundary fault zone, and lower plate to the basaltic volcanic rocks. Cores were recovered from multiple holes that contain a variety of muds from the frontal prism and the plate boundary fault zone, as well as lower plate materials. Comparison with the sediments from Site C0026 provides a basis to interpret the tectonic and sedimentological processes operating in the dynamic environment of the frontal prism. Cores from the plate boundary fault zone provide a unique window into the structural complexity of an active plate boundary fault that is known to host large seismic slip. Two borehole observatories were installed at Site C0019 that contain temperature sensors deployed to take measurements over a period of years and reveal the hydrogeologic structure of the shallow subduction system. These hugely successful drilling operations, combined with postexpedition work to measure the mechanical, frictional, paleomagnetic, and hydrogeologic properties of the core samples and to constrain the history of past seismic slip at Site C0019, will provide an unprecedented opportunity to advance our understanding of shallow subduction systems. Outreach during the expedition leveraged and elevated the success of the operations by sharing the outcomes with a variety of domestic and international audiences, including scientists, students, educators, stakeholders, and the general public. Thanks to the efforts of a large group of onboard outreach officers and their onshore support, activities included ship-to-shore broadcast events; interviews with science party members and crew; the publication of videos, blogs, magazine articles, and social media posts; and development of formalized classroom lesson plans and materials. 

The extremely large slip that occurred on the shallow portion of the Japan Trench subduction zone during the 2011 Mw 9.1 Tohoku-oki earthquake directly contributed to the devastating tsunami that inundated the Pacific coast of Japan. International Ocean Drilling Program (IODP) Expedition 405 aimed to investigate the conditions and processes that facilitated the extremely shallow slip on the subduction interface during the 2011 Tohoku-oki earthquake to improve understanding of the factors that slip to the trench on subduction zones. Expedition 405 implemented a combined logging, coring, and observatory operational plan at two sites: Site C0026 ~8 km seaward of the Japan Trench to characterize the input sediments to the subduction zone and Site C0019 ~6 km landward of the trench where the plate boundary fault zone is present at ~825 meters below seafloor (mbsf). At Site C0026, the input section was logged to ~430 mbsf with a logging-while-drilling (LWD) assembly that characterized the succession of sediments and rocks from the seafloor to the basaltic rocks of the oceanic crust. Cores recovered from four holes as deep as 290 mbsf contain a sequence of hemipelagic and pelagic sediments that will be input into the shallow subduction system and therefore control both the localization of the plate boundary fault zone and the slip behavior of the plate boundary. Site C0019 was previously drilled in 2012 during Integrated Ocean Drilling Program Expedition 343 (Japan Trench Fast Drilling Project [JFAST]), so revisiting this site allowed temporal variations in the frontal prism and plate boundary fault zone to be evaluated. The LWD data to ~960 mbsf characterized the frontal prism, plate boundary fault zone, and lower plate to the basaltic volcanic rocks. Cores were recovered from multiple holes that contain a variety of muds from the frontal prism and the plate boundary fault zone, as well as lower plate materials. Comparison with the sediments from Site C0026 provides a basis to interpret the tectonic and sedimentological processes operating in the dynamic environment of the frontal prism. Cores from the plate boundary fault zone provide a unique window into the structural complexity of an active plate boundary fault that is known to host large seismic slip. Two borehole observatories were installed at Site C0019 that contain temperature sensors deployed to measure temperature over a period of years and reveal the hydrogeologic structure of the shallow subduction system. These hugely successful drilling operations, combined with postexpedition work to measure the mechanical, frictional, paleomagnetic, and hydrogeologic properties of the core samples and to constrain the history of past seismic slip at Site C0019, provide an unprecedented opportunity to advance our understanding of shallow subduction systems. Outreach during the expedition leveraged and elevated the success of the operations by sharing the outcomes with diverse domestic and international audiences, including scientists, students, educators, stakeholders, and the general public. Thanks to the efforts of a large group of onboard outreach officers and their onshore support, activities included ship-to-shore broadcast events; interviews with science party members and crew; the publication of videos, blogs, magazine articles, and social media posts; and development of formalized classroom lesson plans and materials. 

We report laboratory measurements of thermal conductivity and thermal diffusivity and calculated values of volumetric heat capacity for 56 core samples collected during International Ocean Discovery Program Expedition 375 from Sites U1518 and U1519 in the Hikurangi subduction zone. These sites are instrumented with borehole observatories that include downhole temperature sensors, enabling eventual integration of laboratory-derived thermal properties with in situ thermal data. Measurements were conducted under saturated conditions using a transient plane source technique and include repeated tests for quality control. Volumetric heat capacity was calculated as the ratio of thermal conductivity to thermal diffusivity, using measurements obtained simultaneously on the same sample. At Site U1518, thermal diffusivity averages 5.055 ± 0.610 × 10−7 m2/s (± one standard deviation) and volumetric heat capacity averages 2.588 ± 0.277 MJ/(m3·K). At Site U1519, thermal diffusivity averages 5.395 ± 1.027 × 10−7 m2/s and volumetric heat capacity averages 2.574 ± 0.350 MJ/(m3·K). Measured thermal conductivity values average 1.294 ± 0.123 W/(m·K) at Site U1518 and 1.354 ± 0.131 W/(m·K) at Site U1519 and are consistent with previous shipboard results. These new constraints on thermal properties provide key input for interpreting borehole temperature records and modeling transient heat transport in subduction zone fault systems. 

Major element oxides and Cl of dispersed (invisible to the naked eye) volcanic glass shards were measured in clastic sediments of the central Japan Trench recovered at Site M0090 during International Ocean Discovery Program Expedition 386, Japan Trench Paleoseismology. The glass shards were extracted from two giant piston cores, Core 386-M0090B-1H (Sections 1H-15, 80 cm, to 1H-14, 50 cm) and Core 386-M0090D-1H (Sections 1H-14, 0 cm, to 1H-13, 50 cm), which together represent 180 cm of the sediment. High-resolution sampling with 1 and 5 cm spacing (65 samples) aimed to better define the stratigraphic position of the To-Cu marker ash (~6000 y before present), which had previously been identified within this interval. Electron microprobe analysis reveals low-K volcanic glasses (<1.5 wt% K2O; ~67% of the glass data) and medium- and high-K glasses (>1.5 to 5 wt% K2O; ~33% of the glass data) in all 65 samples. The low-K volcanic glasses display the typical compositional characteristics of volcanic glass from the Towada volcano in Northern Honshu and may be mostly of To-Cu origin. The medium- and high-K glasses are likely an assortment of volcanic glasses produced during various Holocene and Pleistocene explosive eruptions of the Honshu arc volcanoes. Variation in grain size fraction, magnetic susceptibility, bulk density, and natural gamma radiation of the sediment sequence sampled suggests that all glass shards were emplaced in turbidite flow either syn- or posteruptively with a major explosive eruption of the Towada volcano. 

This data report presents the leaf wax hydrogen isotopic record from International Ocean Discovery Program Site U1448 in the Andaman Sea. The record includes 270 analyses spanning from the core top to 39.24 m core composite depth below the seafloor. This depth interval spans the past 638 ky with an average temporal resolution of ~2.37 ky (14 cm sample interval). Site U1448 has a published benthic isotope chronostratigraphy as well as previously published paired leaf wax carbon isotope data, enabling a better understanding of hydroclimate in the Andaman region.