Characteristic activities of slow earthquakes in Japan

Obara, Kazushige

doi:10.2183/pjab.96.022

Cited by 23 publications

(24 citation statements)

References 96 publications

(166 reference statements)

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“…1). The regularity and diversity of their rupture patterns have been (2016) and Obara (2020). Depth contours of the upper surface of the Pacific and Philippine Sea plates are based on Baba et al (2002), Nakajima and Hasegawa (2006), Nakajima and Hasegawa (2007), Hirose et al (2008), Nakajima et al (2009), and Kita et al (2010).…”

Section: Introductionmentioning

confidence: 99%

“…3,4,5,and 6). Several remarkable review papers on slow earthquakes have been published (e.g., Peng and Gomberg 2010;Beroza and Ide 2011;Ide 2014;Saffer and Wallace 2015;Obara and Kato 2016;Bürgmann 2018;Obara 2020;Behr and Bürgmann 2021;Kirkpatrick et al 2021). We refer readers to these papers for more information.…”

Section: Brief Introduction To Slow Earthquakesmentioning

confidence: 99%

“…We refer readers to these papers for more information. Obara (2020) extensively reviewed the detailed occurrence patterns of various slow earthquakes, which are not included in this section. Obara and Kato (2016) provided a detailed discussion on the relationship between slow earthquakes and megathrust earthquakes.…”

Section: Brief Introduction To Slow Earthquakesmentioning

confidence: 99%

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A review on slow earthquakes in the Japan Trench

Nishikawa

Ide

Nishimura

2023

Prog Earth Planet Sci

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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 (Mw) 9.0 Tohoku-Oki earthquake occurred. In this paper, we review observational, experimental, and simulation studies on slow earthquakes along the Japan Trench and their research history. By compiling the observations of slow earthquakes (e.g., tectonic tremors, very-low-frequency earthquakes, and slow slip events) and related fault slip phenomena (e.g., small repeating earthquakes, earthquake swarms, and foreshocks of large interplate earthquakes), we present an integrated slow earthquake distribution along the Japan Trench. Slow and megathrust earthquakes are spatially complementary in distribution, and slow earthquakes sometimes trigger fast earthquakes in their vicinities. An approximately 200-km-long along-strike gap of seismic slow earthquakes (i.e., tectonic tremors and very-low-frequency earthquakes) corresponds with the huge interplate locked zone of the central Japan Trench. The Mw 9.0 Tohoku-Oki earthquake ruptured this locked zone, but the rupture terminated without propagating deep into the slow-earthquake-genic regions in the northern and southern Japan Trench. Slow earthquakes are involved in both the rupture initiation and termination processes of megathrust earthquakes in the Japan Trench. We then compared the integrated slow earthquake distribution with the crustal structure of the Japan Trench (e.g., interplate sedimentary units, subducting seamounts, petit-spot volcanoes, horst and graben structures, residual gravity, seismic velocity structure, and plate boundary reflection intensity) and described the geological environment of the slow-earthquake-genic regions (e.g., water sources, pressure–temperature conditions, and metamorphism). The integrated slow earthquake distribution enabled us to comprehensively discuss the role of slow earthquakes in the occurrence process of the Tohoku-Oki earthquake. The correspondences of the slow earthquake distribution with the crustal structure and geological environment provide insights into the slow-earthquake-genesis in the Japan Trench and imply that highly overpressured fluids are key to understanding the complex slow earthquake distribution. Furthermore, we propose that detailed monitoring of slow earthquake activity can improve the forecasts of interplate seismicity along the Japan Trench.

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Section: Introductionmentioning

confidence: 99%

Section: Brief Introduction To Slow Earthquakesmentioning

confidence: 99%

Section: Brief Introduction To Slow Earthquakesmentioning

confidence: 99%

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A review on slow earthquakes in the Japan Trench

Nishikawa

Ide

Nishimura

2023

Prog Earth Planet Sci

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“…While the geophysical expression of ETS is detected in the geophysical record of several active subduction zones, the geological record of ETS (if any) is less obvious and only suggestions have so far been made from the study of geological structures of a few fossil subduction settings formed under a wide spectrum of geothermal gradients. ETS occur both at the up‐ (shallow ETS) and down‐dip limit (deep ETS) of the locked seismogenic zone (review in Behr & Bürgmann, 2021; Gomberg & Group, 2010; Kirkpatrick et al., 2021; Obara, 2020). While the potential recorded evidence of shallow ETS is relatively accessible in nature and can also be directly investigated by deep drillings into the shallow parts of accretionary wedges (Barnes et al., 2020), this is not the case for deep ETS, which remain deeper than ∼25 km.…”

Section: Introductionmentioning

confidence: 99%

Deformation Mechanisms of Blueschist Facies Continental Metasediments May Offer Insights Into Deep Episodic Tremor and Slow Slip Events

2022

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Exhumed fossil subduction zones are archives of the deformation conditions and mechanisms from depths not directly accessible. Microstructural analysis of samples exhumed therefrom offers insights into the micromechanics and deformation processes associated with subduction such as earthquakes, slow earthquakes, and aseismic creep. Subducted and exhumed continental metasediments of the Tuscan Metamorphic Units of the Italian Northern Apennines contain a mylonitic foliation and quartz and carpholite dilational hydroshear veins with crack‐and‐seal textures, both developed at blueschist facies conditions (350–400°C, ∼1 GPa). As shown by overprinting relationships and mineral assemblages, these two structure types formed broadly coeval within the stability field of carpholite. Metaconglomerates and metaquartzarenites deformed mainly by dissolution‐precipitation creep and secondary by dislocation creep. Microstructural and electron backscatter diffraction analyses of the veins suggest only limited recrystallization of quartz fibers by subgrain rotation recrystallization, with adjacent metapelite bands acting as decollement horizons, likely by slip on the basal plane of phyllosilicates. We estimated differential stresses of 43–55 MPa and strain rates between 10−13 and 10−14 s−1 from the vein recrystallized quartz fibers. We propose these microstructures and deformation mechanisms to represent a geological evidence of deep episodic tremor and slow slip events in subducted continental metasediments. Pore pressure cyclically reached supralithostatic values triggering tremors causing fracturing of all involved lithotypes. Likely, slow slip was accommodated preferentially by slip on phyllosilicate bands. Aseismic creep occurred mainly by dislocation creep with subgrain rotation recrystallization in vein quartz, slip on the basal plane of phyllosilicates, and dissolution and precipitation creep in the host rock.

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“…1b). Because slow earthquakes have been attributed to the presence of pore fluids (e.g., Shelly et al 2006;Obara 2020), the intra-plate SSE may also be associated with pore fluid derived from the serpentinites. Because of the uniqueness, the Shirikomadake serpentinite complex provides an ideal opportunity to undertake a detailed investigation of this association.…”

Section: Introductionmentioning

confidence: 99%

Imaging of a serpentinite complex in the Kamuikotan Zone, northern Japan, from magnetotelluric soundings

Ichihara

Mogi

Uchida

et al. 2021

Earth Planets Space

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We conducted magnetotelluric measurements to investigate a large serpentinite complex in the northern Kamuikotan Zone that intruded a Cretaceous–Paleocene forearc sedimentary sequence. The resistivity model we derived by three-dimensional inversion clearly shows a low-resistivity zone beneath the outcrop of the serpentinite complex. We interpret the low-resistivity zone to represent aqueous pore fluid within a serpentinite mélange derived from the subducting Pacific plate or mantle wedge. Previous geological studies in the area have shown that the serpentinite mélange had uplifted during the early Pleistocene. They indicate that the ultramafic rocks and aqueous fluids have continued to rise in the area. The uplifting serpentinite body might have formed a zone enriched in pore fluid that promoted the occurrence of a previously identified intra-plate slow slip event. These results demonstrate the important role of fluid transport during tectonic processes related to uplift in subduction zones.

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Characteristic activities of slow earthquakes in Japan

Cited by 23 publications

References 96 publications

A review on slow earthquakes in the Japan Trench

A review on slow earthquakes in the Japan Trench

Deformation Mechanisms of Blueschist Facies Continental Metasediments May Offer Insights Into Deep Episodic Tremor and Slow Slip Events

Imaging of a serpentinite complex in the Kamuikotan Zone, northern Japan, from magnetotelluric soundings

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