The Jurassic Quiet Zone (JQZ) is a region of low‐amplitude magnetic anomalies whose distinctive character may be related to geomagnetic field behavior. We collected deep‐tow profiles in Pigafetta Basin (western Pacific) where previous data partially covered the JQZ sequence. Our goals were extend survey through JQZ, examine anomaly correlations, and refine preliminary polarity timescale (GPTS) model. series closely spaced over M34 Ocean Drilling Program Hole 801C correlation detail, one...

Abstract The structures of silica (SiO 2 ) glasses at high pressure provide insight into the thermo‐mechanical properties chemically complex amorphous oxides upon stress, compression, and indentation. While much our knowledge on glass has been garnered from high‐resolution solid‐state nuclear magnetic resonance (NMR) by probing evolution spins nuclides interest in oxide glasses, NMR spectrum under pressure, particularly above ∼100 GPa largely remained unexplored. In order to identify key...

Abstract The Endeavour segment of the Juan de Fuca Ridge is one most active and long‐lived hydrothermal areas mid‐ocean ridge system. However, permeability structure that gives rise to long‐term venting at well‐established fields, such as High Rise, Main Endeavour, Mothra not fully understood. Here we jointly invert Pg Sg traveltimes from a seismic refraction experiment conducted using P ‐to‐ S coupling constraints. We then calculate porosity crack density function aspect ratio by applying...

Abstract We analyze seismic records collected at the oldest (170–180 Ma) Pacific seafloor using broadband dispersion array analysis. Using ambient noise and teleseismic waveforms, we measure Rayleigh‐wave phase velocities in a period range of 5–200 s that are inverted for array‐average one‐dimensional isotropic azimuthally anisotropic shear‐wave velocity depth profiles from crust to 300 km. The high‐velocity Lid low‐velocity zone well‐resolved with difference ∼4%, whose transition occurs...

Abstract The northern Central Indian Ridge (CIR) between 8°S and 17°S is composed of seven segments whose spreading rates increase southward from ∼35 to ∼40 mm/yr. During expeditions R/V Onnuri study hydrothermal activity on the CIR in 2009–2011, high‐resolution multibeam mapping was conducted ridge axis basalts were dredged. major trace element Sr‐Nd‐Pb‐He isotopic compositions basaltic glasses dredged require three mantle sources: depleted two distinct enriched sources. southern have Sr,...

The Bismarck Sea, located north of Papua New Guinea and just south the equator, formed during final stages a long, complex geological development Melanesian Borderland, which resulted from Cenozoic convergence between Australian Pacific-Caroline Plates opening back-arc basins. sea, straddles two oppositely facing trenches, inactive Manus trench active Britain trench, covers basins, Basin to west east. These basins are separated by shallow Willaumez-Manus Rise, trending roughly WNW ESE....

ABSTRACT We modified existing methods of noise reduction to data recorded by Japanese broadband ocean-bottom seismometers (BBOBSs) deployed on the western Pacific seafloor conducted as Oldest-1 Array observation. removed tilt and compliance that are dominant in low-frequency seismograms. estimated transfer function from horizontal- vertical-component seismograms remove vertical component. Throughout observation period about one year, was time-invariant phase at low frequencies (<0.06...

Abstract Detailed magnetic analyses of ultramafic rock samples recovered from the Wadi Tayin massif as part Oman Drilling Project provide a unique opportunity to understand properties oceanic lithosphere and its alteration since obduction. We examined 300‐ 400‐m‐long cores 3 sites (BA1B, BA3A, BA4A) that transected crust‐mantle boundary. Serpentinization produces small amount magnetite olivine plays an important role in shaping signature rocks these holes. Our investigation reveals new...

ABSTRACT We characterize the sources of background noise recorded by an ocean-bottom seismometer array deployed on oldest oceanic lithosphere western Pacific plate. This igneous crust is blanketed up to 1000 m cover sediments, making it a unique place investigate correlations between sediment thickness and levels in marine environment. Although data are limited, we found that thicker sediments attenuated short-period amplified long-period levels, agreement with observations made for seismic...

Abstract Oceanic intraplate earthquakes are closely associated with seafloor geologic features, such as knolls, fracture zones, and seamounts. However, this inference is often challenged by significant earthquake location uncertainties difficulties in detecting small earthquakes, largely owing to limited station coverage. In study, we used ocean-bottom seismometer data from the Oldest-1 array consisting of 12 sites, which part Pacific array, construct a one-year catalog for events on oldest...

Sea‐surface scalar magnetic field measurements collected over the East Pacific Rise near 9°30′N and within Brunhes chron have been inverted for magnetization of upper crust. A close track spacing (1–3 km) careful corrections sources background noise make this data set particularly suitable investigating fine‐scale crustal magnetization. well‐defined axial high can be traced throughout survey area but varies considerably along axis. Marked changes in amplitude are often accompanied by offsets...

Abstract The structural modifications in oxide glasses under extreme compression may account for the pressure‐induced increase their mechanical toughness and rigidity, rendering potential technological applications of compressed glasses. High‐resolution solid‐state nuclear magnetic resonance has provided a information regarding by identifying how spins behave interact with nearby elements. However, knowledge pressure above 1 million atmospheres not been available, making origins glass...

Abstract The growth mechanism of the Tibetan Plateau, postulated by a number hypotheses, remains under intense debate. Our analysis recent satellite‐based gravity model reveals that lithosphere has been decoupled and folded. It is further evidenced existence crustal melts channel flow have observed seismic magnetotelluric explorations. Based on 3D geodynamic simulations, we elucidate exact buckling structures in upper crust lithospheric mantle: at mixed wavelengths between ∼240 ∼400 km,...

Problems associated with shear zone development in the lithosphere involve features of widely different time scales, since gradual buildup stress leads to rapid and localized instability. These phenomena have a large stiffness domain cannot be solved efficiently by single time‐integration scheme. This conundrum has forced us use an adaptive time‐stepping scheme, particular, scheme (ATS) where former is adopted for stages quasi‐static deformation latter involving short scale nonlinear...

We have inverted the sea surface total magnetic field measurements of Reykjanes Ridge, between 57°N and 63°N, for crustal magnetization intensity assuming a uniformly thick source layer direction corresponding to geocentric axial dipole field. This section north Mid‐Atlantic Ridge (10 mm/yr half spreading rate) is unique in that it lies within influence Iceland mantle plume, which causes spread obliquely resemble morphologically fast‐spreading ridge. On regional scale anomalies can be...

Abstract The oldest oceanic basin (160–180 Ma) in the western Pacific is birthplace of Plate and thus essential for understanding formation evolution plate. However, upper mantle structure beneath region has not been thoroughly investigated because remoteness difficulties long‐term situ seismic measurements at ocean bottom. From 2018 to 2019, Oldest‐1 experiment on seafloor was conducted as part international Array initiative. We present first three‐dimensional P ‐wave velocity down a depth...

Abstract Scientific developments are considered the primary source of economic prosperity a country. This faith in science appears stronger among economists and policymakers than those involved day-to-day activities. However, policy is often confused with for science. The former dictated by national interest ideology, including long-term plans Because it so crucial, whether to let scientists formulate nation long-standing issue many countries. Policymakers politicians generally provide...

Abstract Mid‐ocean ridge basalts (MORB) from the Central Indian Ridge (CIR) between 12° and 17°S show a wide range of geochemical isotopic variations. Particularly, MORB segment 14° 15°S are more enriched in incompatible trace elements with radiogenic Sr Pb isotope unradiogenic Nd values than lavas 15° 16°S features normal MORB. However, causes for enrichment poorly constrained. In this study, we re‐examined CIR to new data obtained based on high spatial resolution sampling better understand...

SUMMARY This study presents the velocity structures of seafloor sediment across Pacific using teleseismic body waves recorded by arrays ocean bottom seismometers (OBSs). We apply method inverting multicomponent stacked autocorrelation functions and radial-component waveform waves. analyze OBSs distributed Ocean, through a wide range water depths equipped with various sensor types. The inverted models agreeing measurements drilling samples demonstrate broad applicability employing inversion...

Abstract Since 2017, requesting ship time has become possible for university researchers and businesses on research vessels. They include Isabu Onnuri of the Korea Institute Ocean Science Technology (KIOST) icebreaking vessel Araon Polar Research (KOPRI). There was no regulation barring chartering significant national scientific infrastructure in first place, but exorbitant cost had made their usage virtually impossible. Shared Use Committee (SUC) set up to handle applications coordinate...

We present a C++ package entitled 1D Controlled Source Electromagnetic Method using Quadrature With Extrapolation (1DCSEMQWE), which computes the electromagnetic field for one-dimensional model in geophysics. This supports computation both electric and magnetic dipole sources. Transmitters receivers can be placed anywhere layered model. The formulation of frequency domain avoids positive exponential terms, leading to higher accuracy. In particular, we introduce new tool quadrature with...

International Conference on Geophysics of Slab Dynamics;Jeju Island, South Korea, 19–22 August 2012 In a recent meeting Jeju community researchers, half from East Asia and North America Europe, came together to study subduction complementary points view—seismology, geodynamics, mineral physics, tectonics—to enhance the synergy between subduction‐related disciplines. The discussion focused predictability largest earthquakes, origin interplate volcanism in Asia, challenges for numerical...