Months-long thousand-kilometre-scale wobbling before great subduction earthquakes

Bedford, Jonathan; Moreno, Marcos; Deng, Zhiguo; Oncken, Onno; Schurr, Bernd; John, Timm; Báez, J. C.; Bevis, Michael

doi:10.1038/s41586-020-2212-1

Cited by 61 publications

(65 citation statements)

References 63 publications

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“…Chen et al [32] utilized the same method proposed in [14] to examine the filtered displacements before the 2011 M9 Tohoku earthquake in Japan and found that the crustal displacements in areas with an epicentral distance >1500 km are related to the event. Note that the similar anomalous phenomena of the crustal displacements associated with earthquakes can also be obtained by using the traditional method in a distinct place [13]. Chen et al [16] utilized a statistical method to examine the relationship between seismo-crustal displacements in wide areas and earthquakes.…”

Section: Discussionmentioning

confidence: 98%

“…Atmospheric acoustic-gravity waves have been considered as one of the factors that induce changes in ionospheric density, which could cause seismo-ionospheric perturbations before earthquakes [8][9][10][11][12]. However, seeking seismic-related vibration sources such as crustal displacements [13][14][15][16][17][18] and ground motion occurring before earthquakes has remained a great challenge until the present. On 6 February 2016, the M6.…”

Section: Introductionmentioning

confidence: 99%

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Determination of Epicenters before Earthquakes Utilizing Far Seismic and GNSS Data: Insights from Ground Vibrations

Chen

Yeh

et al. 2020

Remote Sensing

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Broadband seismometers, ground-based Global Navigation Satellite Systems (GNSS), and magnetometers that were located within an epicentral distance of approximately 150 km consistently observed the novel anomalous behaviors of the common-mode ground vibrations approximately 5–10 days before the M6.6 Meinong earthquake in Taiwan. The common-mode ground vibrations with amplitudes near 0.1 m at frequencies ranging from 8 × 10−5 to 2 × 10−4 Hz were generated near the region close to the epicenter of the impending earthquake. The common-mode vibrations were consistently observed in seismic and GNSS data associated with five other earthquakes in four distinct areas. The results reveal that the common-mode vibrations could be a typical behavior before earthquakes. The causal mechanism of common-mode vibrations can be attributed to crustal resonance excitations before fault dislocations occur. Potential relationships with other pre-earthquake anomalies suggest that the common-mode vibrations could be ground motion before earthquakes, which was investigated for a significant length of time.

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Section: Discussionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Determination of Epicenters before Earthquakes Utilizing Far Seismic and GNSS Data: Insights from Ground Vibrations

Chen

Yeh

et al. 2020

Remote Sensing

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“…Before the analytical processes in this study, we assumed that earthquakes with relatively small magnitude can be the cracks and potentially related to the far mainshocks based on the large seismogenic areas (Bedford et al, 2020). The minimum magnitudes of completeness M c are 2.0 and 0.0 that can be determined by the declustered earthquake catalogs in Taiwan and Japan, respectively (also see Figs.…”

Section: Methodsmentioning

confidence: 99%

“…Stress accumulates in a local region near a hypocenter, 3334 C.-H. Chen et al: Spatiotemporal changes of seismicity rate during earthquakes triggering earthquake occurrence that is concluded from the sparse distribution of seismometers. Bedford et al (2020) analyzed the GNSS data and observed crustal deformation in a thousand-kilometer-scale area before the great earthquakes in the subduction zones. Chen et al (2011Chen et al ( , 2020a filtered the crustal displacements before earthquakes using the GNSS data through the Hilbert-Huang transform.…”

Section: Introductionmentioning

confidence: 99%

Spatiotemporal changes of seismicity rate during earthquakes

Chen

Sun

Wen

et al. 2020

Nat. Hazards Earth Syst. Sci.

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Abstract. Scientists demystify stress changes within tens of days before a mainshock and often utilize its foreshocks as an indicator. Typically, foreshocks are detected near fault zones, which may be due to the distribution of seismometers. This study investigates changes in seismicity far from mainshocks by examining tens of thousands of M≥2 quakes that were monitored by dense seismic arrays for more than 10 years in Taiwan and Japan. The quakes occurred within epicentral distances ranging from 0 to 400 km during a period of 60 d before and after the mainshocks that are utilized to exhibit common behaviors of seismicity in the spatiotemporal domain. The superimposition results show that wide areas exhibit increased seismicity associated with mainshocks occurring more than several times to areas of the fault rupture. The seismicity increase initially concentrates in the fault zones and gradually expands outward to over 50 km away from the epicenters approximately 40 d before the mainshocks. The seismicity increases more rapidly around the fault zones approximately 20 d before the mainshocks. The stressed crust triggers ground vibrations at frequencies varying from ∼5×10-4 to ∼10-3 Hz (i.e., variable frequency) along with earthquake-related stress that migrates from exterior areas to approach the fault zones. The variable frequency is determined by the observation of continuous seismic waveforms through the superimposition processes and is further supported by the resonant frequency model. These results suggest that the variable frequency of ground vibrations is a function of areas with increased seismicity leading to earthquakes.

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“…Both models experience stick-slip dynamics The continuous scientific and technological advancements allow detecting transient deformation signals occurring on short times-scales (fractions of the seismic cycle) along convergent margins and sampling the megathrust seismic cycle with progressively denser and higher quality data. For example, even if the underlying source process still has to be identified, both the 2010 Maule (Chile) and 2011 Tohoku-Oki (Japan) earthquakes have been preceded by potentially diagnostic geodetic transients lasting several months and spanning thousands of kilometers (Bedford et al, 2020). Satellite measurements (e.g., InSAR studies; Jolivet et al, 2020), dense geodetic (e.g., Michel et al, 2018) and seismic (e.g., Brodsky and Lay, 2014) monitoring -both onshore and offshore-is able to record a wide range of deformation signal frequencies (i.e., from earthquakes s.s. to low frequency earthquakes and tremors) and the improvement of the quantity, quality and accessibility of databases of convergent margin observables (e.g., geodesy.unr.edu/NGLStationPages/gpsnetmap/ GPSNetMap.html; geofon.gfz-potsdam.de; www-solid.eps.s.…”

Section: Challenges and Future Directionsmentioning

confidence: 99%

Empirical Analysis of Global-Scale Natural Data and Analogue Seismotectonic Modelling Data to Unravel the Seismic Behaviour of the Subduction Megathrust

et al. 2020

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Subduction megathrusts host the Earth’s greatest earthquakes as the 1960 Valdivia (Mw 9.5, Chile), the largest earthquake instrumentally recorded, and the recent 2004 Sumatra-Andaman (Mw 9.2, Indonesia), 2010 Maule (Mw 8.8, Chile), and 2011 Tohoku-Oki (Mw 9.1, Japan) earthquakes triggering devastating tsunamis and representing a major hazard to society. Unravelling the spatio-temporal pattern of these events is thus a key for seismic hazard assessment of subduction zones. This paper reviews the current state of knowledge of two research areas–empirical analysis of global-scale natural data and experimental data from an analogue seismotectonic modelling—devoted to study cause-effect relationships between subduction zone parameters and the megathrust seismogenic behavior. The combination of the two approaches overcomes the observational bias and inherent sampling limitations of geological processes (i.e., shortness of instrumental and historical data, decreasing completeness and resolution with time into the past) and allows drawing appropriately from multiple disciplines with the aim of highlighting the geodynamic conditions that may favor the occurrence of giant megathrust earthquakes.

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Months-long thousand-kilometre-scale wobbling before great subduction earthquakes

Cited by 61 publications

References 63 publications

Determination of Epicenters before Earthquakes Utilizing Far Seismic and GNSS Data: Insights from Ground Vibrations

Determination of Epicenters before Earthquakes Utilizing Far Seismic and GNSS Data: Insights from Ground Vibrations

Spatiotemporal changes of seismicity rate during earthquakes

Empirical Analysis of Global-Scale Natural Data and Analogue Seismotectonic Modelling Data to Unravel the Seismic Behaviour of the Subduction Megathrust

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