Re-estimated fault model of the 17th century great earthquake off Hokkaido using tsunami deposit data

Ioki, Kei; Tanioka, Yuichiro

doi:10.1016/j.epsl.2015.10.009

Cited by 62 publications

(76 citation statements)

References 16 publications

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“…These uplift residuals suggest that an afterslip distribution since the 2nd year changed from the 3-month distribution and that the afterslip magnitude below the land is larger than that predicted from our logarithmic function model throughout the analyzed periods. Transient uplift after the seventeenth-century Kurile tsunamigenic mega-earthquake, which is suggested to reach almost M9 (Satake et al 2008;Ioki and Tanioka 2016), was reported by previous studies (e.g., Sawai et al 2004) and has been considered to be caused by aseismic creep in the downdip extension on the plate interface. Our results also suggest that large afterslip, which occurred in the down-dip region of the coseismic slip region, is a plausible explanation for transient uplift in the postseismic period.…”

Section: Characteristics On Observed and Calculated Surface Displacementsupporting

confidence: 54%

Characteristics of postseismic deformation following the 2003 Tokachi-oki earthquake and estimation of the viscoelastic structure in Hokkaido, northern Japan

Itoh

Nishimura

2016

Earth Planet Sp

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Postseismic deformation of the 2003 Tokachi-oki earthquake (M w 8.0) has been observed by GNSS. We analyzed the deformation observed in Hokkaido in the 2nd to the 7th year following the 2003 Tokachi-oki earthquake and examined the effect of two major mechanisms (i.e., afterslip and viscoelastic relaxation) for the observed postseismic deformation by fitting it with a model consisting of afterslip and viscoelastic relaxation. The thickness of the lithosphere, the viscosity of the asthenosphere, and the time decaying constant of afterslip were estimated to be 50 km, 2.0 × 10 19 Pa s, and 0.110 year, respectively, which are concordant with those in the Tohoku region estimated in previous studies. The revealed characteristics of postseismic deformation are as follows. At most of the used stations, afterslip played the dominant role in the 2nd year and was still sustained near the coseismic area even in the 7th year. However, the calculated velocity due to viscoelastic relaxation was comparable to that due to afterslip at the stations in northern Hokkaido after the 5th year. Because the calculated velocity due to viscoelastic relaxation was landward near the coseismic slip area, afterslip near the coseismic slip area will be biased to be smaller if viscoelastic relaxation is ignored. A systematic spatial pattern of the residuals considering afterslip only highlights an importance for explaining the observation data. We also examined the effect of viscoelastic relaxation due to afterslip for the parameter estimation and found that it was too small to affect the estimated structure parameters.

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Section: Characteristics On Observed and Calculated Surface Displacementsupporting

confidence: 54%

Characteristics of postseismic deformation following the 2003 Tokachi-oki earthquake and estimation of the viscoelastic structure in Hokkaido, northern Japan

Itoh

Nishimura

2016

Earth Planet Sp

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“…For the former area (which is assigned to class 2), the large values of both

\overset{normalΔ σ}{true}

and

\overset{normalΔ normals normals}{true}

(Table ) suggest that it is prone to producing M w ≥ 9 events, which is consistent with the tsunami deposit studies on the coast [ Nanayama et al ., ; Sawai et al ., ], although the available max. magnitude is M w 8.8 for the seventeenth century event [ Ioki and Tanioka , ].…”

Section: Discussionmentioning

confidence: 99%

Subducted sediment thickness and M_w 9 earthquakes

Seno

2017

JGR Solid Earth

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I measure the thickness of subducted sediment (Δss) beneath the décollement in the fore‐arc wedge and show that the average value of Δss over a subduction zone segment ( truenormalΔnormalsnormals¯) is greater than 1.3 km in segments where Mw ≥ 9 earthquakes have occurred and less than 1.2 km in segments without such large earthquakes. In a previous study, I showed that the stress drop (Δσ) of large earthquakes (Mw ≥ 7) averaged over a subduction zone segment ( truenormalΔσ¯) is larger in segments where Mw ≥ 9 earthquakes have occurred than in segments without such an event. It has also been shown that truenormalΔσ¯ is linearly related to 1 − λ (λ = the pore fluid pressure ratio in the interplate megathrust). In this study, I revise the previous estimates of truenormalΔσ¯ and λ and show that there is a positive correlation between truenormalΔnormalsnormals¯, truenormalΔσ¯, and 1 − λ. I present a model that relates Δss to 1 − λ based on the porous flow of H2O in the subducted sediments, which gives a theoretical basis for the correlation between truenormalΔnormalsnormals¯ and truenormalΔσ¯. The combination of these parameters thus provides a better indicator for identifying segments where Mw ≥ 9 earthquakes may occur. Based on this, I propose that the tectonic environments where such huge events are likely to occur are (1) near collision zones, (2) near subduction of spreading centers, and (3) erosive margins with compressional fore arcs. Near the Japanese islands, SE Hokkaido is prone to such an event, but the Nankai Trough is not.

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“…The asperity in the shallower part of ADDS ruptures only in the case of a megathrust event as a millennial event. This rupture process has been observed in the 2011 Tohoku-oki megathrust and the 1964 great Alaska earthquake, and the other candidate for this type of a gigantic tsunami is the 17th century tsunami in Hokkaido, Japan [21]. The global importance of different tsunami excitation due to the seismic segmentation of ADDS or ASSS is stressed and is now open to future studies.…”

Section: Discussionmentioning

confidence: 99%

“…Considering the reason (F) in the above, we should remind readers that tsunami earthquakes, earthquakes with slow-slip characteristics along the Sanriku Coast of the Tohoku, have occurred, where the source region of the 2011 megathrust earthquake located. The subduction zone shows a developed Horst and Graben structure [19][20][21], which is formed by sedimentation and related to the generation of tsunami earthquakes. The source region is not similar to the sedimentary layer in the Japan Sea.…”

Section: Discussionmentioning

confidence: 99%

“…The asperity stays in a narrow part of the subduction interface in ASSS. Horst and Graben and seamounts are considered to be responsible for generating tsunami earthquakes [19][20][21]. As well as Horst and Graben, surface roughness such as seamounts and oceanic ridges plays an important role in blocking seismic segments (dotted broken lines) along the subduction zone [2].…”

Section: Diversity Of Megathrust Earthquakes In the Worldmentioning

confidence: 99%

See 1 more Smart Citation

Tsunamigenic Earthquakes at Along-dip Double Segmentation and Along-strike Single Segmentation near Japan

Koyama

Tsuzuki

Yomogida

2015

JMSE

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A distinct difference of the earthquake activity in megathrust subduction zones is pointed out, concerning seismic segmentations in the vicinity of Japan-that is, the apparent distribution of earthquake hypocenters characterized by Along-dip Double Segmentation (ADDS) and Along-strike Single Segmentation (ASSS). ADDS is double aligned seismic-segmentation of trench-ward seismic segments along the Japan Trench and island-ward seismic segments along the Pacific coast of the Japan Islands. The 2011 Tohoku-oki megathrust earthquake of Mw9.0 occurred in ADDS. In the meantime, the subduction zone along the Nankai Trough, the western part of Japan, is the source region of a multiple rupture of seismic segments by the 1707 Houei earthquake, the greatest earthquake in the history of Japan. This subduction zone is narrow under the Japan Islands, which is composed of single aligned seismic-segmentation side by side along the Nankai Trough, which is typical of ASSS. Looking at the world seismicity, the 1960 and 2010 Chile megathrusts, for example, occurred in ASSS, whereas the 1952 Kamchatka and the 1964 Alaska megathrusts occurred in ADDS. These megathrusts in ADDS result from the rupture of strong asperity in the trench-ward seismic segments. Since the asperity of earthquakes in OPEN ACCESSJ. Mar. Sci. Eng. 2015, 3 1179 ASSS is concentrated in the shallow part of subduction zones and the asperity of frequent earthquakes in ADDS is in deeper parts of the island-ward seismic segments than those of ASSS, there must be a difference in tsunami excitations due to earthquakes in ADDS and ASSS. An analysis was made in detail of tsunami and seismic excitations of earthquakes in the vicinity of Japan. Tsunami heights of ASSS earthquakes are about two times larger than those of ADDS earthquakes with the same value of seismic moment. The reason for this different tsunami excitation is also considered in relation to the seismic segmentations of ADDS and ASSS.

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Re-estimated fault model of the 17th century great earthquake off Hokkaido using tsunami deposit data

Cited by 62 publications

References 16 publications

Characteristics of postseismic deformation following the 2003 Tokachi-oki earthquake and estimation of the viscoelastic structure in Hokkaido, northern Japan

Characteristics of postseismic deformation following the 2003 Tokachi-oki earthquake and estimation of the viscoelastic structure in Hokkaido, northern Japan

Subducted sediment thickness and M_w 9 earthquakes

Tsunamigenic Earthquakes at Along-dip Double Segmentation and Along-strike Single Segmentation near Japan

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Re-estimated fault model of the 17th century great earthquake off Hokkaido using tsunami deposit data

Cited by 62 publications

References 16 publications

Characteristics of postseismic deformation following the 2003 Tokachi-oki earthquake and estimation of the viscoelastic structure in Hokkaido, northern Japan

Characteristics of postseismic deformation following the 2003 Tokachi-oki earthquake and estimation of the viscoelastic structure in Hokkaido, northern Japan

Subducted sediment thickness and Mw 9 earthquakes

Tsunamigenic Earthquakes at Along-dip Double Segmentation and Along-strike Single Segmentation near Japan

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Subducted sediment thickness and M_w 9 earthquakes