Multivariate Statistical and Multiproxy Constraints on Earthquake‐Triggered Sediment Remobilization Processes in the Central Japan Trench

The Kanto region, central Japan situated in the complex tectonic region where two oceanic plates subducts from the Japan trench and Sagami trough. Although many previous studies clarified repeated Mw~6.6 Slow Slip Events (SSEs) with a duration of a week in an offshore region of the Boso Peninsula along the Sagami trough, the number of the detected SSEs are limited and overall activity of SSEs have not been fully understood in these regions. We, here, applied our SSE detection in these regions to the whole available GNSS dataset for a quarter century spanning from 1994 to 2019 and clarify the relation between SSE and tremor distribution.We use daily coordinates at 291 GNSS stations using a precise point positioning strategy of the GIPSY 6.4 software. We apply the method of Nishimura et al. (2013) and Nishimura (2014) to detect a jump associated with short-term SSEs in GNSS time-series and estimate their fault models from observed displacements. A rectangular fault on the Philippine Sea or the Pacific plates is assumed for each SSE. The stacking of GNSS time-series based on the displacement predicted by the fault model [Miyaoka and Yokota, 2012] enable us to estimate duration of SSEs.&#160;&#160;We detected &#8805; 150 possible SSEs along both the Japan trench and Sagami trough but we here focus on SSEs along the southernmost part of the Japan trench. Total slip distribution of the detected possible SSEs shows that large slip (&#8805; 0.3 m) is limited near the trench. A comparison with low-frequency tremors (LFTs) along the Japan trench (Nishikawa et al., 2019) suggests SSEs occur in the same depth range (10-20 km) of LFTs but their distribution is rather complimentary whereas a minor tremor activity exists at the edge of the SSE total slip. This complimentary distribution is contrast to overlapping distribution of SSEs and LFTs observed in a deep episodic and tremor region in the other subduction zones including southwest Japan. Another distinctive feature is that SSEs continuously occur from the trench to a depth of ~60 km only at ~ 35.5&#186;N. Because the subducted seamounts locate at this latitude, geometry of plate interface may control a genesis of SSEs in these regions.

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Large Coseismic Slip to the Trench During the 2011 Tohoku-Oki Earthquake

Annual Review of Earth and Planetary Sciences ◽

10.1146/annurev-earth-071719-055216 ◽

2020 ◽

Vol 48 (1) ◽

pp. 321-343 ◽

Cited By ~ 1

Author(s):

Shuichi Kodaira ◽

Toshiya Fujiwara ◽

Gou Fujie ◽

Yasuyuki Nakamura ◽

Toshiya Kanamatsu

Keyword(s):

Subduction Zone ◽

Seismic Data ◽

Direct Evidence ◽

Japan Trench ◽

Fault Rupture ◽

Coseismic Slip ◽

Central Japan ◽

Characteristic Factor ◽

Strong Ground ◽

Large Tsunami

The strong ground motions, large crustal deformation, and tsunami generated by the 2011 Tohoku-oki earthquake ( Mw 9.1) reveal that a large coseismic slip likely propagated to shallow depth in the Japan Trench. Although data acquired by onshore networks cannot resolve the slip behavior of the updip fault rupture, marine geophysical and geological studies provide direct evidence of coseismic slip to the trench. Differential bathymetry data show ∼50 m of coseismic seafloor displacement extending to the central Japan Trench (38–39.2°N). Seismic data show that coseismic slip ruptured the seafloor within the trench. Pelagic clays may have promoted slip propagation to shallow depths, whereas disturbed/metamorphosed clays may have restricted slip to the main rupture zone. Those observations imply that a smooth, broadly distributed, weak, clay-rich sediment in a shallow part of a subduction zone is a characteristic factor that can foster a large coseismic slip to the trench and, consequently, the generation of a large tsunami. ▪ During the 2011 Tohoku-oki earthquake ( Mw 9.1), more than ∼50 m of slip occurred on a fault that ruptured the seafloor in the central Japan Trench. ▪ The fault rupture reaching the seafloor caused a large tsunami. ▪ Marine geophysical explorations revealed that a clay-rich sediment in the subduction zone was one factor fostering the large fault slip. ▪ Understanding of slip behavior in the shallow portion of a subduction zone will help us prepare for future large tsunamis along the Japan-Kuril Trench.

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Long-term variations in individual particle types in the aerosol of Phoenix, Arizona, as determined using automated electron microprobe analysis and multivariate statistical techniques

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100149544 ◽

1993 ◽

Vol 51 ◽

pp. 742-743

Author(s):

Karen A. Katrinak ◽

James R. Anderson ◽

Peter R. Buseck

Keyword(s):

Electron Microprobe ◽

Fine Fraction ◽

Coarse Fraction ◽

Motor Vehicles ◽

Multivariate Statistical Methods ◽

Multivariate Statistical ◽

X Ray ◽

Mineral Particles ◽

Anthropogenic Air Pollutants

Aerosol samples were collected in Phoenix, Arizona on eleven dates between July 1989 and April 1990. Elemental compositions were determined for approximately 1000 particles per sample using an electron microprobe with an energy-dispersive x-ray spectrometer. Fine-fraction samples (particle cut size of 1 to 2 μm) were analyzed for each date; coarse-fraction samples were also analyzed for four of the dates.The data were reduced using multivariate statistical methods. Cluster analysis was first used to define 35 particle types. 81% of all fine-fraction particles and 84% of the coarse-fraction particles were assigned to these types, which include mineral, metal-rich, sulfur-rich, and salt categories. "Zero-count" particles, consisting entirely of elements lighter than Na, constitute an additional category and dominate the fine fraction, reflecting the importance of anthropogenic air pollutants such as those emitted by motor vehicles. Si- and Ca-rich mineral particles dominate the coarse fraction and are also numerous in the fine fraction.

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Angular Calibration of Ribosomal Subuntts in Factor Space

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100181063 ◽

1990 ◽

Vol 48 (1) ◽

pp. 462-463

Author(s):

Minakhi Pujari ◽

Joachim Frank

Keyword(s):

Three Dimensional ◽

Carbon Layer ◽

Uranyl Acetate ◽

Particle Analysis ◽

Factor Space ◽

Multivariate Statistical ◽

Ribosomal Subunits ◽

Layer Method ◽

Dimensional Reconstruction ◽

Number Of Particles

In single-particle analysis of macromolecule images with the electron microscope, variations of projections are often observed that can be attributed to the changes of the particle’s orientation on the specimen grid (“rocking”). In the multivariate statistical analysis (MSA) of such projections, a single factor is often found that expresses a large portion of these variations. Successful angle calibration of this “rocking factor” would mean that correct angles can be assigned to a large number of particles, thus facilitating three-dimensional reconstruction.In a study to explore angle calibration in factor space, we used 40S ribosomal subunits, which are known to rock around an axis approximately coincident with their long axis. We analyzed micrographs of a field of these particles, taken with 20° tilt and without tilt, using the standard methods of alignment and MSA. The specimen was prepared with the double carbon-layer method, using uranyl acetate for negative staining. In the MSA analysis, the untilted-particle projections were used as active, the tilted-particle projections as inactive objects. Upon tilting, those particles whose rocking axes are parallel to the tilt axis will change their appearance in the same way as under the influence of rocking. Therefore, each vector, in factor space, joining a tilted and untilted projection of the same particle can be regarded as a local 20-degree calibration bar.

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Molecular Views of Ice-Embedded Lumbricus Terrestris Erythrocruorin Obtained By Invariant Classification

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100181002 ◽

1990 ◽

Vol 48 (1) ◽

pp. 450-451

Author(s):

Michael schatz ◽

Joachim Jäger ◽

Marin van Heel

Keyword(s):

Image Interpretation ◽

Lumbricus Terrestris ◽

Reference Image ◽

Large Set ◽

Multivariate Statistical ◽

Data Set ◽

Low Contrast ◽

Negative Stain ◽

Reference Images ◽

Statistical Resolution

Lumbricus terrestris erythrocruorin is a giant oxygen-transporting macromolecule in the blood of the common earth worm (worm "hemoglobin"). In our current study, we use specimens (kindly provided by Drs W.E. Royer and W.A. Hendrickson) embedded in vitreous ice (1) to avoid artefacts encountered with the negative stain preparation technigue used in previous studies (2-4).Although the molecular structure is well preserved in vitreous ice, the low contrast and high noise level in the micrographs represent a serious problem in image interpretation. Moreover, the molecules can exhibit many different orientations relative to the object plane of the microscope in this type of preparation. Existing techniques of analysis requiring alignment of the molecular views relative to one or more reference images often thus yield unsatisfactory results.We use a new method in which first rotation-, translation- and mirror invariant functions (5) are derived from the large set of input images, which functions are subsequently classified automatically using multivariate statistical techniques (6). The different molecular views in the data set can therewith be found unbiasedly (5). Within each class, all images are aligned relative to that member of the class which contributes least to the classes′ internal variance (6). This reference image is thus the most typical member of the class. Finally the aligned images from each class are averaged resulting in molecular views with enhanced statistical resolution.

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