T. Nishikawa 교수

Investigating slow earthquake activity in subduction zones provides insight into the slip behavior of megathrusts, which can provide important clues about the rupture extent of future great earthquakes. Using the S-net ocean-bottom seismograph network along the Japan Trench, we mapped a detailed distribution of tectonic tremors, which coincided with very-low-frequency earthquakes and a slow slip event. Compiling these and other related observations, including repeating earthquakes and earthquake

Abstract Slow earthquakes are episodic slow fault slips. They form a fundamental component of interplate deformation processes, along with fast, regular earthquakes. Recent seismological and geodetic observations have revealed detailed slow earthquake activity along the Japan Trench—the subduction zone where the March 11, 2011, moment magnitude ( M w ) 9.0 Tohoku-Oki earthquake occurred. In this paper, we review observational, experimental, and simulation studies on slow earthquakes along the Ja

Abstract Earthquake swarms are characterized by an increase in seismicity rate that lacks a distinguished main shock and does not obey Omori's law. At subduction zones, they are thought to be related to slow‐slip events (SSEs) on the plate interface. Earthquake swarms in subduction zones can therefore be used as potential indicators of slow‐slip events. However, the global distribution of earthquake swarms at subduction zones remains unclear. Here we present a method for detecting such earthquak

Abstract Slow slip events (SSEs) on the plate interface are closely related to the occurrence of earthquakes and often trigger earthquake swarms in subduction zones. Moreover, some SSEs, accompanied by intensive foreshocks, precede large interplate earthquakes. Therefore, detecting and monitoring SSEs is important for assessing the potential of future large earthquakes. However, there are many SSEs not followed by large earthquakes, and it is unclear whether these can be distinguished from SSEs

Abstract Tectonic properties strongly control variations in seismicity among subduction zones. In particular, fluid distribution in subduction zones influences earthquake occurrence, and it varies among subduction zones due to variations in fluid sources such as hydrated oceanic plates. However, the relationship between variations in fluid distribution and variations in seismicity among subduction zones is unclear. Here we divide Earth's subduction zones into 111 regions and estimate background

For linear acceleration of high energy protons an alternating periodic structure operated in a ½π standing wave mode has the advantage of relative immunity from beam loading and detuning effects while sacrificing little in shunt impedance when compared to π mode operation in a uniform periodic structure. The dispersion curve of the alternating periodic structure is derived from an analysis of a chain of coupled cavities, in each of which the fields are expanded in normal modes. By introducing th

The differential asymmetry ratio for the process $\ensuremath{\gamma}+n\ensuremath{\rightarrow}p+{\ensuremath{\pi}}^{\ensuremath{-}}$ was measured at 90\ifmmode^\circ\else\textdegree\fi{} in the center-of-mass system and for incident photon energies from 352 to 550 MeV. The observed asymmetries are larger than the values predicted from the theory by Berends, Donnachie, and Weaver. A smaller ${M}_{1}$- amplitude gives better agreement between the experiment and the theory.

Abstract Earthquake swarms, which are anomalous increases in the seismicity rate without a distinguishable mainshock, often accompany transient aseismic processes, such as fluid migration and episodic aseismic slip along faults. Investigations of earthquake swarm activity can provide insights into the causal relationship between aseismic processes and seismicity. Slow slip events (SSEs) along the plate interface in the Hikurangi Trench, New Zealand, are often accompanied by intensive earthquake

Abstract Slow slip events (SSEs) at subduction zone plate boundaries sometimes trigger earthquake swarms and megathrust earthquakes. The causal relationship between SSEs and seismicity has been studied worldwide, but the epidemic‐type aftershock‐sequence (ETAS) model, which is a standard statistical model of seismicity, does not explicitly consider the seismicity‐triggering effect of SSEs. Therefore, if an SSE occurs at a plate boundary, probabilistic earthquake forecasts based on the ETAS model

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Status of the KEK TRISTAN project, the Phase I of which has been approved since 1981, is reported with an emphasis on its accelerator design and construction. The design of accelerator complex has mostly been fixed. Construction of accelerator enclosure and production of accelerator components are under way with a target day for the first e+ e- collisions in 1986.

Abstract Slow earthquakes are slow fault slip events. Quantifying and monitoring slow earthquake activity characteristics are important, because they may change before large earthquakes occur. Statistical seismicity models are useful for quantifying seismicity characteristics. However, no standard statistical model exists for slow earthquake activity. This study used a high-quality catalog of low-frequency earthquakes (LFEs), a type of slow earthquake, in the Nankai subduction zone from April 20

S. Giordano has proposed a multistem structure for drift tube linacs which has the advantage of relative immunity from beam loading and detuning 1 effects due to the greater mode-spacing near the TM mode.In a recent 010 paper, Giordano and Hannwacker have measured and discussed a new set of modes which are associated with the resonance in the circumferential fields of the 2 stem systems.These modes, called TS(N) modes, couple to the usual TM 108 01£ modes and lead to the shaping of the dispersio