Gregory F. Moore

University of Hawaiʻi at Mānoa | UH Manoa · Department of Earth Sciences

Large seamounts and basement relief cause permanent deformation when they collide with the overriding plate at subduction zones. The resulting structural and compositional heterogeneities have been implicated as controlling factors in megathrust slip behaviour. Subducting seamounts may temporarily lock plates, favouring subsequent large earthquakes...

Calcareous rocks are commonly found in subduction zones, but few studies have investigated the consolidation and compactive deformation of these rocks prior to subduction, and their potential effects on subduction and accretionary processes are thus poorly understood. Using drilling data obtained during International Ocean Discovery Program (IODP)...

Recent studies have documented the occurrence of shallow very low frequency earthquakes (VLFE) in subduction zones. The heterogeneity of the materials or stresses that act on the plate interface results in the variable slip rate. Stress on the décollement can be controlled by the décollement geometry and the regional stress, which is also able to c...

We focus here on the different forcings that controlled the deep-marine sediment dynamics and associated stratigraphic pattern in the Nankai subduction zone, especially in the Kumano forearc basin. In this study, based on high-resolution subbottom profiler data, we investigate the Upper Pleistocene–Holocene deposits of the tectonically active Kuman...

Subducted sediment plays a key role in modulating pore pressure and seismic behavior at subduction zones. We investigated the seismic character of incoming sediments to test how sediment and basement variations relate to the along‐strike changes within the accretionary prism and plate boundary conditions at the Nankai Trough. High‐resolution seismi...

For more than half a century, exploring a complete sequence of the oceanic crust from the seafloor through the Mohorovičić discontinuity (Moho) and into the uppermost mantle has been one of the most challenging missions of scientific ocean drilling. Such a scientific and technological achievement would provide humankind with profound insights into...

Three-dimensional (3D) pre-stack depth migrated seismic data are used to analyse the geometry and growth of shallow faults associated with tectonic shortening in four (4) prominent thrust anticlines off Nankai, SE Japan. The four thrust anticlines show a trench-ward increase in horizontal shortening and deform the seafloor at present. They shortene...

Significant along-strike changes in the protothrust zone at the toe of the Nankai Trough accretionary prism were imaged in new high-resolution seismic reflection data. The width of the protothrust zone varies greatly along strike; two spatially discrete segments have a wide protothrust zone (∼3.3–7.8 km, ∼50–110 protothrusts), and two segments have...

Pyay sub-basin is located in the southern part of the Central Myanmar Forearc Basin, an elongate belt of en-echelon folds and thrust faults formed as a result of the hyper-oblique convergence of the India and Asia plates. Limited neotectonic studies suggest that the Pyay Fault is a major Pliocene inverted structure that trapped the hydrocarbons in...

Three‐dimensional (3‐D) seismic reflection data and sediment cores record ~2.87 million years of structural and depositional history of a trench slope basin along the outer Nankai accretionary prism, southwest Japan. Numerous mass transport deposits (MTDs) and fault structures are present in the basin. Here, we investigate the links between slope f...

Slow slip events (SSEs) accommodate a significant proportion of tectonic plate motion at subduction zones, yet little is known about the faults that actually host them. The shallow depth (<2 km) of well-documented SSEs at the Hikurangi subduction zone offshore New Zealand offers a unique opportunity to link geophysical imaging of the subduction zon...

To reveal the detailed deformation structures related to plate subduction in the Nankai Trough, we applied up-to-date technologies to improve our 3-D seismic images. This region is dominated by a megasplay fault system that consists of a coseismic out-of-sequence thrust branching from the plate interface and separating the inner and outer accretion...

The western margin of Myanmar is the northern extension the active Sunda (India-Eurasia) subduction zone. Coastal regions and offshore islands have remarkable exposures of chaotic rock terranes along wave-cut terraces that allow characteristics of tectonic, sedimentary and diapiric mélanges to be recognized. Tectonic shear zones (tectonic mélanges)...

Seismic refraction and multi-channel seismic reflection surveys were conducted on the northeastern Hawaiian Arch to examine the effect of hotspot volcanism on the seismic structure of the crust and uppermost mantle. The crustal thickness deduced from the refraction data was typical for oceanic crust, which suggests that magmatic underplating does n...

Abstract Three-dimensional (3D) seismic data from the southern Kumano Basin of southwest Japan image a nested series of moderately sized mass transport deposits (MTDs) that slid from a slope along the seaward side of the forearc basin. The deposits are dated to be approximately 0.3 to 0.9 Ma. These MTDs are likely linked to the movement along a pro...

The combination of recent megathrust earthquakes that have ruptured the frontal portions of accretionary prisms and historical evidence for large wedge-front, fold-and-thrust belt events has sparked interest in the development of wedge-front fault systems. Here we explore the formation of these faults using two-dimensional finite-difference models...

New, high-resolution multi-beam bathymetric data from RV Sonne cruise SO251 show a widely variable surface morphology along the southern Kumano Basin and Nankai accretionary prism off SW Japan. Combined with a three-dimensional seismic volume, these data provide insight into the ubiquitous and varied nature of faulting typical of accretionary prism...

We present an activity focusing on an interactive sonar display for educational outreach promoting education of both marine geology and basic geophysical concepts. Students act as chief scientists for a scaled-down sonar research cruise by creating cruise tracklines, collecting data, and visualizing and interpreting the results. The exhibit uses co...

Previous studies have suggested predominant extensional tectonics acting, at present, on the Nankai Accretionary Prism (NAP), and following a parallel direction to the convergence vector between the Philippine Sea and Amur Plates. However, a complex set of thrusts, pop-up structures, thrust anticlines and strike-slip faults is observed on seismic d...

Methane hydrate concentrated zones (MHCZs) have become targets for energy exploration along continental margins worldwide. In 2013, exploratory drilling in the eastern Nankai Trough at Daini Atsumi Knoll confirmed that MHCZs tens of meters thick occur directly above bottom simulating reflections imaged in seismic data. This study uses 3-dimensional...

Subduction erosion is a commonly invoked model that is used to explain the tectonic subsidence of the Japan Trench forearc slope, although other models have explained the morphology and history of the margin. New multichannel seismic reflection and bathymetric data collected after the 2011 Tohoku earthquake provide the opportunity to investigate th...

The processes of flow deformation of marine mass-transport sediments, including their ability to affect the underlying substrate and add mass during sediment flow events, are addressed based on sedimentological analyses of strata from the distal part of a ∼61-m-thick mass-transport deposit (MTD 6) drilled during Integrated Ocean Drilling Program (I...

Accretionary prisms commonly grow seaward, with the strata of the inner prism consisting of older, previously accreted outer prism rocks overlain by thick forearc basin strata. We focus on the Nankai Trough inner accretionary prism using three-dimensional (3D) seismic data and logging data from the Integrated Ocean Drilling Program (IODP). We updat...

Large-scale landsliding is a common process in the Kumano Forearc Basin of the Nankai Trough accretionary prism. We use a 3D seismic data volume to map the seafloor reflection, which shows that there are two surficial landslides, one rotational slump ~3.4 km wide, 1.8 km long and 150 m thick and one disintegrative slide that has left a seafloor sca...

We determined the seismic attenuation structure of the Kumano Basin, a forearc basin in the central part of the Nankai subduction zone. Despite its importance for understanding the physical condition of the Earth's interior and seismic wave propagation processes, the attenuation factor Q has been poorly estimated in the crustal layers of the offsho...

Submarine slope failure and derived sediment gravity flows are recognized as a major sedimentary process in basins worldwide. Their large failure volumes and long-runout distances pose significant tsunami hazard for offshore and coastal facilities, and thus it is important to understand the mechanisms and processes involved in the initiation of slo...

The determination of in situ stress states is vital in understanding the behavior of faults and subsequent seismogenesis of accretionary prisms. In this paper, a high quality 3D seismic volume is used to map the depth of the extensional-compressional decoupling (ECD) boundary in the accretionary prism of Nankai, with the prior knowledge that strike...

University of Hawaii Geophysical Society (UHGS), an Society of Exploration Geophysicists (SEG) Student Chapter, was seeking to further motivate students to pursue the geosciences by demonstrating a miniature, real-time sonar-mapping cruise. UHGS designed a physical model that actively demonstrates how scientists employ geophysical methods to map th...

Bottom simulating reflections (BSRs), appearing in seismic surveys along continental margins worldwide, are considered to be robust indicators of the presence of gas hydrates. Yet despite several decades of research, the nature of BSRs including their occurrence, distribution patterns, amplitude strength, continuity, and phase characteristics conti...

Multichannel seismic reflection lines image the subducting Pacific Plate to approximately 75 km seaward of the Japan Trench and document the incoming plate sediment, faults, and deformation front near the 2011 Tohoku earthquake epicenter. Sediment thickness of the incoming plate varies from <50 to >600 m with evidence of slumping near normal faults...

Sedimentary deposits in the Kumano Forearc Basin of the Nankai Accretionary Prism, offshore Kii Peninsula, Japan, record complex interactions between sedimentation and deformation processes that control the stratigraphic architecture of the basin. This study correlates regional 3D seismic data with sediment cores from IODP NanTroSEIZE drill sites C...

For this work were used three high-quality 3D seismic volumes from SE Japan and SE Brazil, together with borehole data from the Nankai Trough. We show that, on 3D seismic data, seismic texture is defined as a reflection amplitude pattern that is characterised by the magnitude and variation of neighbouring data in a seismic volume (Chopra and Marfur...

Three-dimensional (3-D) seismic volumes from southeast Brazil, southeast Japan, and borehole data from the Ocean Drilling and Integrated Ocean Drilling Programs are used to demonstrate a new method to distinguish mass-transport deposits (MTDs) from confining hemipelagites, quantify MTDs internal architecture, and assess their reservoir potential or...

Integrated Ocean Drilling Program (IODP) Site C0002 (proposed Site NT3-01B; Fig. F1) is the centerpiece of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) project (Tobin and Kinoshita, 2006). Planned scientific and technical targets for IODP Expedition 338 included collecting logging-while-drilling (LWD), cuttings, and core data in the...

A 3D seismic volume from the Nankai Trough accretionary wedge (SE Japan) is used to evaluate the subsurface distribution of gas hydrates as a function of structural and stratigraphic complexity, variable heat flow patterns and the presence of sub-surface fluid conduits. Eleven equations were modified for depth, pressure and temperature, modelled in...