Progress in Earth and Planetary Science

Abstract The ratio of P-wave to S-wave velocity (Vp/Vs) is a key indicator of subsurface fluid pressure and rock properties. However, its spatial distribution in offshore regions has been poorly constrained because of difficulties in resolving shallow seismic velocity structures, particularly Vs structures. Recent advances in distributed acoustic sensing (DAS) enable dense seismic observations ev…

Abstract X-ray fluorescence (XRF) core scanners have advantages in nondestructive measurements of the elemental compositions of sediment cores with high stratigraphic resolution. To estimate elemental flux using sediment compositions measured by the XRF core scanner, total mass flux must be precisely calculated using the dry bulk density (DBD) and linear sedimentation rate records. In this study,…

Abstract Evaluating the hydraulic properties of fractured rock masses in the subsurface is crucial for geoengineering applications and mitigating geohazards. Understanding these properties around faults is particularly important due to their impact on fluid behavior. Various methods have been developed to evaluate formation permeability, including in situ tests on boreholes, laboratory tests on r…

Abstract Brachiopod shells have been widely used as paleoenvironmental recorders because of their robust preservation in fossil records. However, accurately reconstructing past seawater temperatures from their oxygen (δ 18 O) and clumped isotope compositions requires identifying shells/shell portions that are minimally affected by kinetic isotope effects (KIE) and diagenetic alteration. This stud…

Abstract The Nankai Trough, offshore of Southwest Japan, represents a plate subduction zone where a long history of devastating mega-earthquake and tsunami events has been best documented. Because of this societal relevance, the area has been extensively studied and monitored for several decades. Among the Nankai Trough region, the Eastern Nankai Trough and the Enshu Forearc Basin remain a focal …

Abstract Stable isotope analysis is useful in elucidating the flow of elements among organisms and environments. Understanding the movement of organisms is important for the conservation of ecosystems, and radiogenic strontium stable isotope ratios (⁸⁷Sr/⁸⁶Sr) are used as a tool to elucidate the relationship between fish and their habitat water and to investigate the movements and habitat ranges …

Abstract Symbiotic relationships of microorganisms including eukaryotic algae and prokaryotes affect holobiont nitrogen metabolism and provide survival advantages in extreme environments; however, the influences of different symbionts on nitrogen metabolism in host organisms remain unclear. By tracing the nitrogen isotopic composition (δ 15 N) of amino acids (AAs), it is possible to constrain the…

Abstract Salt marshes, which sustain high productivity, serve as essential living environments for a wide range of organisms. The aquatic food web in salt marshes is basically supported by the high primary production of aquatic algae within the intertidal zone and the organic matter contributed from the terrestrial ecosystems, including the adjacent supratidal zone. As salt marshes facilitate the…

Abstract This study investigates the coseismic displacement field caused by the Mw 7.7 earthquake that struck Myanmar on March 28, 2025, along a segment of the Sagaing Fault, a well-known, right-lateral strike-slip fault. To such a purpose, a combination of satellite synthetic aperture radar (SAR)-based techniques, specifically Pixel Offset Tracking (POT), Multiple Aperture Interferometry (MAI), …

Abstract We combined a regional aeromagnetic survey with an uncrewed aerial vehicle (UAV; drone)-based magnetic survey to map low-magnetization zones associated with intensive hydrothermal activity on the western flank of the central cones of Aso Volcano, Kyushu, Japan. Three-dimensional (3D) magnetic inversion of regional helicopter-borne data shows that the major fumarole and hot-spring areas: …

Abstract Stokes drift associated with surface waves induces mass transport, which interacts with ocean currents to modify dynamics from situations without waves. The effect of Stokes drift can be parameterized through “Stokes forcing” terms derived from wave–current interaction theory, and an increasing number of regional and global ocean models incorporate these terms to represent wave effects o…

Abstract The Arctic's rapid transformation due to climate change significantly impacts Northern Eurasia. Eastern Siberia experienced increased summer precipitation and permafrost thaw in the mid-2000s, leading to wetter surfaces and higher river runoff. Furthermore, Arctic warming is linked to winter cooling in Eurasia, indicating a major disruption in the interconnected Arctic Ocean–atmosphere–v…

Abstract Serpentinization-associated geofluid systems are thought to facilitate the abiotic synthesis of organic compounds, which may have played a key role in the prebiotic chemical evolution on the early Earth. The Mariana convergent margin hosts one of the serpentinization-associated systems, which has evolved into serpentinite mud volcanoes at the forearc region. Previous investigations have …

Abstract Long-range transported dust across the North Pacific influences the climate by altering radiative forcing, affecting cloud properties as it acts as an ice nucleus, and impacting surface ocean biogeochemistry and carbon cycling through the supply of iron to the subarctic Pacific, a region characterized by high nutrients and low chlorophyll. Asian dust has for a long time been considered t…

Abstract Changes in the physical and biogeochemical conditions of the ocean over time can affect marine ecosystems. In this study, we use biogeochemical observational data for the past 25 years (1999–2023) to investigate ocean acidification and changes in biological production at site K2 (47˚ N, 160˚ E) in the western subarctic region of the North Pacific Ocean. During this period, satellite-deri…

Abstract Hachijo Island, part of the Izu-Ogasawara Islands, is situated near major plate boundaries, including the Nankai Trough, Sagami Trough, and Izu-Ogasawara Trench, making it highly susceptible to tsunamis triggered by earthquakes in these regions. Despite this vulnerability, limited tsunami research has been conducted in the area. This study aimed to uncover the tsunami history of Hachijo …

Abstract Stable carbon isotopic compositions of amino acids ( δ 13 C AA ) in organisms potentially record information on carbon sources and flow in food webs. In this study, we report δ 13 C values of 16 proteinogenic amino acids in marine consumers and evaluate their changes associated with the trophic transfer by using a newly developed analytical method based on multidimensional preparative li…

Abstract The Laboratory OROCHI Simulator (LOROS) is an emulator of the Optical RadiOmeter composed of CHromatic Imagers (OROCHI), a multispectral and multiview imaging system for the Japan Aerospace Exploration Agency (JAXA) Martian Moons eXploration (MMX) spacecraft, that will study Phobos and Deimos with the objective of determining their origin. OROCHI consists of 8 visible/near-infrared (390–…

Abstract To assess the permeability structure of the oceanic lithosphere, we analyzed the field-based vein distribution and geometry in the Wadi Haymiliyah area of the Oman ophiolite. The mineral-filled veins are a fossil record of fluid circulation, and we divided the veins into four categories: amphibole vein, epidote vein, prehnite vein, and serpentine vein. Amphibole and epidote veins are for…