Lineaments and earthquake ruptures on the East Japan megathrust

Lister, Gordon; Tkalčić, Hrvoje; Hejrani, Babak; Koulali, Achraf; Rohling, Eelco J.; Forster, Marnie; McClusky, S.

doi:10.1130/l687.1

Cited by 7 publications

(3 citation statements)

References 56 publications

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“…In Japan, focal mechanism catalogs of regional centroid moment tensor (CMT) solutions (e.g., F-net moment tensor (MT): Fukuyama et al 1998;Kubo et al 2002; Accurate and QUick Analysis system for source parameters (AQUA) CMT: Matsumura et al 2006) and first-motion solutions compiled by the Japan Meteorological Agency (JMA) have been routinely determined and contributing to studying the stress field. Some studies redetermined CMT solutions in the Tohoku region to discuss the stress field before and after the Tohoku-oki earthquake (e.g., Asano et al 2011;Lister et al 2018). However, any of the systems cannot determine focal mechanisms for M w ≤ 3.5 offshore earthquakes.…”

Section: Introductionmentioning

confidence: 99%

CMT inversion for small-to-moderate earthquakes applying to dense short-period OBS array at off Ibaraki region

Yamaya

Mochizuki

Akuhara

et al. 2022

Earth Planets Space

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We conducted centroid moment tensor (CMT) inversion for small-to-moderate aftershocks in the off Ibaraki region of the 2011 off the Pacific coast of Tohoku earthquake. In this study, we used high-frequency (0.4–1.0 Hz) seismograms from a dense array of short-period ocean bottom seismometers (OBSs) and a reliable three-dimensional (3-D) seismic velocity model. Higher frequency analysis and dense OBS arrays offer CMT solutions with high spatial resolutions. Since our OBS array observed aftershocks occurring immediately following the 2011 off the Pacific coast of Tohoku earthquake, we determined 536 CMT solutions for small-to-moderate aftershocks in the off Ibaraki region (JMA-scale magnitudes of 2.5–4.0). According to our CMT solutions, characteristics of the aftershock activities in the off Ibaraki region are classified into 5 groups: (1) thrust earthquakes, which are considered as interplate earthquakes, separated by the large slip area of the 2011 Ibaraki-oki earthquake (the largest $${\mathrm{M}}_{\mathrm{w}}$$ M w 7.6 aftershock of the 2011 off the Pacific coast of Tohoku earthquake) and the tectonic tremors; (2) intraslab strike-slip earthquakes located at the north of the fault area of the 2011 Ibaraki-oki earthquake; (3) intraslab normal-fault earthquakes, which suggest a tensional stress field within the subducting Pacific Plate due to the plate bending by the overriding Philippine Sea Plate; (4) various earthquake focal mechanisms above a subducting seamount, which suggest the 3-D complex fractures; and (5) normal-fault earthquakes shallower than the interplate earthquakes, which were possibly caused by the heterogeneity of the subducting seamount. Graphical Abstract

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Section: Introductionmentioning

confidence: 99%

CMT inversion for small-to-moderate earthquakes applying to dense short-period OBS array at off Ibaraki region

Yamaya

Mochizuki

Akuhara

et al. 2022

Earth Planets Space

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“…Most listric faults appear to sole out into a horizontal décollement coincident with the upper portion of the MBF, supporting a direct link between extension and mobility within the MBF (McNeill et al, ; Rau & Grocock, ; Wagner & Batatian, ). It is significant that these listric faults have both alternating landward and seaward vergence, since this style of dual‐fault orientation indicates extension by graben formation, rather than just gravitational collapse of the shelf edge (Illies, ; Lister et al, ; Schlische, ). The archive MCS profiles also show clear growth strata bounded by the normal and listric faults, indicating roughly continuous movement since the Pleistocene or earlier (McNeill et al, ; see Figures a and b).…”

Section: Washington Margin Geologymentioning

confidence: 99%

Anomalous Concentration of Methane Emissions at the Continental Shelf Edge of the Northern Cascadia Margin

et al. 2019

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A recent compilation of methane plumes detected offshore Washington State includes 1,772 individual bubble streams issuing from 491 discrete vent sites. The majority of these plume sites form a narrow 10‐km‐wide band located shallower than 250‐m water depth, with most sites located near the 175‐m‐deep continental shelf break that tracks the head scarps of large submarine canyons. Archive multichannel seismic profiles over the Cascadia shelf and uppermost margin that were co‐located within a few hundred meters with active emission sites show that methane bubble streams arise from listric/normal faults and triangular‐shaped regions of disturbed seismic reflectors that intersect the seafloor and extend several kilometers into the subsurface. Geological processes were evaluated for producing the narrow emission site depths including nonuniform distribution of methane within the Cascadia accretionary sediment wedge and horizontal transfer of groundwater from onshore subaerial sources. A model of enhanced sediment permeability arising from a contrasting response between the inner and outer portions of the accretionary wedge deformation during a megathrust earthquake cycle appears the most likely mechanism. This faulting is generated during extension of the overriding plate during megathrust earthquake cycles, with semicontinuous permeability enhancement of the fluid pathways from excitation by contemporary incident seismic waves.

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“…For example, the method of localizing seismogenic hazardous areas based on mapping the lineament density maxima [7] can be called quite popular. As another example, we can point to the study of the empirical relationship of individual faults, manifested in the system of lineament structures on remote sensing images, on the one hand, and earthquake epicenters, on the other hand [8]. There is an interesting work on the assessment of the variability of the directional rose of lineaments under conditions of high-intensity seismogenic disturbances [9].…”

Section: Introductionmentioning

confidence: 99%

Increasing Resolution of Seismic Hazard Mapping on the Example of the North of Middle Russian Highland

et al. 2021

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The standard problem of engineering geophysics, solved for road and house building and other construction types, is in the localization of areas with increased mobility in the upper part of a geological cross-section and in the parameterization of this mobility in terms of seismic intensity. There is a standard approach, according to which researchers assess the elastic strength characteristics of the core to a depth of about 30 m, implement the accumulation of seismogram observations, simulate accelerograms for particular conditions and, taking into account the data of complex geophysical methods, calculate the increment of seismic intensity as one of the parameters of a seismic hazard. The final result of this approach has the form of a seismogenic hazard map and a set of recommendations including the consideration of identified areas with a significant increasing seismic intensity increment, due to the peculiarities of the geological structure of polygons. This result is reliable, but very expensive, and requires the development of primary estimations of the rock massif with reduced resistance to external loads, which would optimize the efforts in engineering drilling and in field geophysical measurements in order to densify their spatial grid in the vicinity of a priori known positions with an increased seismogenic hazard. In addition, relatively sparse grids of wells, as well as local geophysical profiles laid under conditions of a complicated landscape, do not accurately localize risky areas in order to focus the attention of builders on strengthening the specific part of raised constructions. Following the wishes of our customers and relying on long-term testing of our interpretational developments, we formed an approach to primary hazard forecasting based on remote sensing data and digital elevation models, which can be classified as data with relatively free access. This article presents the results of research which was based on these free-of-charge data and which was developed in the field of construction of ground engineering structures for agricultural purposes, where one of the factors of mobility in the upper part of a cross-section is intensive karstification. Basically, the construction area according to the general seismic zoning maps is seismologically passive, though the relatively fast dynamics of karst determines the relevance of the detailed seismic zoning. The results of our interpretations are verified by deep geological and structural reconstructions based on wave analogies. The representativeness of the final forecast was confirmed by subsequent seismic assessments, which is related to the scientific novelty of the presented article. The authors’ technology for the qualitative and quantitative interpretation of remote sensing data and digital elevation models with high resolution provides the opportunity to increase the spatial resolution of seismic microzonation forecasts, implemented by standard geophysical methods, and it determines the practical significance of completed research.

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Lineaments and earthquake ruptures on the East Japan megathrust

Cited by 7 publications

References 56 publications

CMT inversion for small-to-moderate earthquakes applying to dense short-period OBS array at off Ibaraki region

CMT inversion for small-to-moderate earthquakes applying to dense short-period OBS array at off Ibaraki region

Anomalous Concentration of Methane Emissions at the Continental Shelf Edge of the Northern Cascadia Margin

Increasing Resolution of Seismic Hazard Mapping on the Example of the North of Middle Russian Highland

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