Megathrust reflectivity reveals the updip limit of the 2014 Iquique earthquake rupture

Ma, Bo; Geersen, Jacob; Lange, Dietrich; Klaeschen, Dirk; Grevemeyer, Ingo; Contreras‐Reyes, Eduardo; Petersen, Florian; Riedel, Michael; Xia, Yueyang; Tréhu, Anne M.; Kopp, Heidrun

doi:10.1038/s41467-022-31448-4

Cited by 7 publications

(3 citation statements)

References 57 publications

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“…These layer structures probably represent low-velocity underthrust sediments atop the upper crust of the subducted Kyushu-Palau Ridge. In general, spatial variations in seismic reflectivity at the plate boundary is closely correlated with the physical properties and plate coupling conditions, which are highly influenced by in-situ fluid pressure 30 , 31 . At shallow depths where the temperature is below 150 °C, the pore fluid pressure is primarily controlled by the compaction and dehydration reactions of clay-rich sediments 3 .…”

Section: Resultsmentioning

confidence: 99%

Upper-plate conduits linked to plate boundary that hosts slow earthquakes

Arai,

Miura,

Nakamura

et al. 2023

Nat Commun

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In shallow subduction zones, fluid behavior impacts various geodynamic processes capable of regulating slip behaviors and forming mud volcanoes. However, evidence of structures that control the fluid transfer within an overriding plate is limited and the physical properties at the source faults of slow earthquakes are poorly understood. Here we present high-resolution seismic velocity models and reflection images of the Hyuga-nada area, Japan, where the Kyushu-Palau ridge subducts. We image distinct kilometer-wide columns in the upper plate with reduced velocities that extend vertically from the seafloor down to 10–13 km depth. We interpret the low-velocity columns as damaged zones caused by seamount subduction and suggest that they serve as conduits, facilitating vertical fluid migration from the plate boundary. The lateral variation in upper-plate velocity and seismic reflectivity along the plate boundary correlates with the distribution of slow earthquakes, indicating that the upper-plate drainage system controls the complex pattern of seismic slip at subduction faults.

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Section: Resultsmentioning

confidence: 99%

Upper-plate conduits linked to plate boundary that hosts slow earthquakes

Arai,

Miura,

Nakamura

et al. 2023

Nat Commun

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“…To the north of the mainshock latitude, aseismic slip before and after the mainshock overlap. Excess fluid pressure along the megathrust there may prevent the accumulation of elastic strain (Ma et al., 2022). The possible termination of the 1877 rupture is located there (Figure 1a) where long‐term locking rates were inferred to be low (Jolivet et al., 2020; Li et al., 2015; Métois et al., 2016; Schurr et al., 2014).…”

Section: Discussionmentioning

confidence: 99%

Largest Aftershock Nucleation Driven by Afterslip During the 2014 Iquique Sequence

Itoh,

Socquet,

Radiguet

2023

Geophysical Research Letters

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Various earthquake models predict that aseismic slip modulates the seismic rupture process but actual observations of such seismic‐aseismic interaction are scarce. We analyze seismic and aseismic processes during the 2014 Iquique earthquake sequence. High‐rate Global Positioning System displacements demonstrate that most of the early afterslip is located downdip of the M 8.1 mainshock and is accompanied by decaying aftershock activity. An intriguing secondary afterslip peak is located ∼120 km south of the mainshock epicenter. The area of this secondary afterslip peak likely acted as a barrier to the propagating mainshock rupture and delayed the M 7.6 largest aftershock, which occurred 27 hr later. Interevent seismicity in this secondary afterslip area ended with a M 6.1 near the largest aftershock epicenter, kicking the largest aftershock rupture in the same area. Hence, the interevent afterslip likely promoted the largest aftershock nucleation by destabilizing its source area, favoring a rate‐dependent cascade‐up model.

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“…To the north of the mainshock latitude, aseismic slip before and after the mainshock overlap. Excess fluid pressure along the megathrust there may prevent the accumulation of elastic strain (Ma et al, 2022). The possible termination of the 1877 rupture is located there (Figure 1a) where longterm locking rates were inferred to be low (Jolivet et al, 2020;Li et al, 2015;Métois et al 2016;Schurr et al, 2014).…”

Section: Along-strike Megathrust Heterogeneity and Rupture Segmentationmentioning

confidence: 99%

Largest aftershock nucleation driven by afterslip during the 2014 Iquique sequence

Itoh¹,

Socquet²,

Radiguet³

2023

Preprint

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Various earthquake source models predict that aseismic slip modulates the seismic rupture process. However, observations of aseismic slip associated with earthquakes are scarce, which has left the earthquake source model controversial. Here, we characterise seismic and aseismic processes for 3 days during the 2014 Iquique earthquake sequence in northern Chile by analysing seismicity and crustal deformation time series measured by high-rate Global Positioning System (GPS). We demonstrate that the early afterslip started immediately after the M 8.1 mainshock and led to the largest M 7.6 aftershock 27 hours later, located ~120 km to the south. At the mainshock latitude, the interevent early afterslip is located downdip of the mainshock rupture, and is associated with aftershocks. These afterslip and aftershocks exhibit a rapid temporal decay. In contrast, south of the mainshock slip patch, a peak of afterslip separates the mainshock rupture from the largest aftershock, suggesting that this area acted as a barrier to the southward propagation of the mainshock rupture. Seismicity count and moment accelerate in this southern area during the interevent stage. We conclude that the largest aftershock nucleation was driven by the interevent afterslip. The mechanical connection between sequential great earthquakes can therefore be mediated by aseismic slip.

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Megathrust reflectivity reveals the updip limit of the 2014 Iquique earthquake rupture

Cited by 7 publications

References 57 publications

Upper-plate conduits linked to plate boundary that hosts slow earthquakes

Upper-plate conduits linked to plate boundary that hosts slow earthquakes

Largest Aftershock Nucleation Driven by Afterslip During the 2014 Iquique Sequence

Largest aftershock nucleation driven by afterslip during the 2014 Iquique sequence

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