Linear Relationship Between Aftershock Productivity and Seismic Coupling in the Northern Chile Subduction Zone

Hainzl, Sebastian; Sippl, Christian; Schurr, Bernd

doi:10.1029/2019jb017764

Cited by 28 publications

(29 citation statements)

References 44 publications

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“…Aftershocks activity has been related to fault properties as state of stress (Shebalien & Narteau, 2017), rupture processes (Poli et al, 2016), seismic coupling (Hainzl et al, 2019) and the thermal state of the slab, with colder slabs showing a greater number of aftershocks (Wiens & Gilbert, 1996). A main issue is to understand if this general decrease in the number of aftershocks is real, or it is due to the lack of near-field data (Li et al, 2018).…”

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confidence: 99%

Northern Chile intermediate-depth earthquakes controlled by plate hydration

Cabrera

Ruiz

Poli

et al. 2020

Geophysical Journal International

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Summary We investigate the variations of the seismic source properties and aftershock activity using kinematic inversions and template-matching, for six large magnitude intermediate-depth earthquakes occurred in northern Chile. Results show similar rupture geometry and stress drop values between 7–30 MPa. Conversely, aftershocks productivity systematically decreases for the deeper events within the slab. Particularly there is a dramatic decrease in aftershock activity below the 400–450°C isotherm-depth, which separates high and low-hydrated zones. The events exhibit tensional focal mechanisms at unexpected depths within the slab, suggesting a deepening of the neutral plane, where the extensional regimen reaches the 700–800°C isotherm-depth. We interpret the reduction of aftershocks in the lower part of the extensional regime as the absence of a hydrated-slab at those depths. Our finding highlights the role of the thermal-structure and fluids in the subducting plate, in controlling the intermediated-depth seismic activity and shed new light in their causative mechanism.

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confidence: 99%

Northern Chile intermediate-depth earthquakes controlled by plate hydration

Cabrera

Ruiz

Poli

et al. 2020

Geophysical Journal International

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“…The relationship between the seismicity parameters that describe aftershock generation and the geophysical features in the seismogenic zone has been explored by previous studies (e.g., Mogi 1967;Ogata 2004;Marsan and Helmstetter 2017;Nandan et al 2017;Zakharova et al 2017;Hainzl et al 2019). For example, Ogata (2004) suggested that aftershock productivity ( ) is high on the boundary of each source region that hosts M7-class earthquakes along the subduction zone, offshore NE Japan.…”

Section: Discussionmentioning

confidence: 99%

“…Previous studies have discussed the relationship between the observed seismicity and geophysical features in the seismogenic zone (e.g., Ogata 2004;Nandan et al 2017;Zeng et al 2018;Ben-Zion and Zaliapin 2019;Hainzl et al 2019). For example, Zeng et al (2018) demonstrated that spatial variations in the background seismicity rate in California correlate with the maximum shear strain rate, and Ogata (2004) suggested that aftershock productivity (one of the parameters that define the modified Omori law) is high on the boundary of the source region hosting M7-class earthquakes along the offshore Tohoku region.…”

Section: Introductionmentioning

confidence: 99%

Spatial variations in seismicity characteristics in and around the source region of the 2019 Yamagata-Oki Earthquake, Japan

Ueda

Kato

Ogata

et al. 2020

Preprint

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The 2019 Mj 6.7 Yamagata-Oki earthquake occurred adjacent to the northeastern edge of the source region of the 1964 Mj 7.5 Niigata earthquake, offshore of Yamagata Prefecture, Japan. Few aftershocks occurred in the source region of the Yamagata-Oki earthquake immediately following the Niigata earthquake, and the recent seismicity rate in this region is low compared with the source region of the Niigata earthquake. This spatial variation in seismicity may allow us to elucidate plausible physical processes that shape the spatiotemporal evolution of these shallow-crustal environments. Here, we investigate the spatial variations in seismicity characteristics by applying the HIerarchical Space–Time Epidemic Type Aftershock Sequence (HIST-ETAS) model to an earthquake catalog compiled by the Japan Meteorological Agency for events in and around the Yamagata-Oki earthquake rupture region. We compare spatial variations in the background seismicity rate and aftershock productivity estimated from the HIST-ETAS model with the geophysical features in the study region. The background seismicity rate is high along the eastern margin of the Sea of Japan and correlates well with a previously identified zone that possesses a high geodetic E-W strain rate. The two major earthquakes occurred in and around a high E-W strain rate zone, suggesting that the background seismicity rate may serve as a key parameter for evaluating seismic hazard across the Japanese Archipelago. Furthermore, the source region of the Yamagata-Oki earthquake has a higher aftershock productivity and lower seismic-wave velocity than that of the Niigata earthquake. We interpret this low-velocity zone to be a well-developed damaged rock that resulted in an increase in aftershock productivity based on previous laboratory experiments and numerical results; this damage makes the rock more ductile at the macroscopic scale. The higher ductility in the source region of the Yamagata-Oki earthquake may have worked as a barrier against the propagation of dynamic rupture that occurred during the Niigata earthquake.

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“…Marsan and Helmstetter (2017) investigated the fluctuations of aftershock productivity in Southern California, and related the results to the stress drop variability of mainshocks. Hainzl et al (2019) found a linear relationship between the aftershock productivity and the coupling coefficient in the Chile subduction zone.…”

mentioning

confidence: 89%

“…Hainzl et al. (2019) found a linear relationship between the aftershock productivity and the coupling coefficient in the Chile subduction zone.…”

Section: Introductionmentioning

confidence: 99%

Heterogeneity of Aftershock Productivity Along the Mainshock Ruptures and Its Advantage in Improving Short‐Term Aftershock Forecast

2021

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This study introduces an improved hypocentral version of the space‐time Epidemic‐Type Aftershock Sequence (ETAS) model, entitled as the 3D‐finite source (3D‐FS) ETAS model, and applies it to the analysis of the Southern California earthquake catalog. By stochastic reconstruction, we are able to reconstruct the patterns of aftershock productivity density along the mainshock ruptures. Detailed analysis of the productivity patterns reveals that: (1) Directly triggered aftershocks make up 21% to 41% of all earthquakes within the mainshock rupture areas, and show significant spatial heterogeneity and temporal migrations; (2) Major aftershocks tend to locate in low productivity areas, at the edges of clusters formed by small aftershocks; (3) Large slip areas are depleted of aftershocks, over 60% of all productivity distributes in areas with slip less than 0.3 times of the maximum slip, and the trajectory of the productivity pattern on the fault plane demonstrates apparent compensation to coseismic slip. We relate the difference in triggering abilities of four mainshocks to the heat flow in corresponding regions. Simulation results suggest that the 3D‐FS ETAS model has apparent advantages of improving the performance of short‐term aftershock forecast. Moreover, the later aftershocks are more correlated with the locations of subsequent events than earlier aftershocks, suggesting that the migration of aftershocks is important for mitigating aftershock hazard.

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Linear Relationship Between Aftershock Productivity and Seismic Coupling in the Northern Chile Subduction Zone

Cited by 28 publications

References 44 publications

Northern Chile intermediate-depth earthquakes controlled by plate hydration

Northern Chile intermediate-depth earthquakes controlled by plate hydration

Spatial variations in seismicity characteristics in and around the source region of the 2019 Yamagata-Oki Earthquake, Japan

Heterogeneity of Aftershock Productivity Along the Mainshock Ruptures and Its Advantage in Improving Short‐Term Aftershock Forecast

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