scholarly journals Recurrent slow slip event likely hastened by the 2011 Tohoku earthquake

2012 ◽  
Vol 109 (38) ◽  
pp. 15157-15161 ◽  
Author(s):  
Hitoshi Hirose ◽  
Hisanori Kimura ◽  
Bogdan Enescu ◽  
Shin Aoi
Keyword(s):  
Subduction Zones ◽  
Earthquake Swarm ◽  
Stress Transfer ◽  
Tohoku Earthquake ◽  
Plate Boundaries ◽  
Earthquake Catalog ◽  
Slow Slip ◽  
The 2011 Tohoku Earthquake ◽  
Boso Peninsula ◽  
Simple Physical Model

Slow slip events (SSEs) are another mode of fault deformation than the fast faulting of regular earthquakes. Such transient episodes have been observed at plate boundaries in a number of subduction zones around the globe. The SSEs near the Boso Peninsula, central Japan, are among the most documented SSEs, with the longest repeating history, of almost 30 y, and have a recurrence interval of 5 to 7 y. A remarkable characteristic of the slow slip episodes is the accompanying earthquake swarm activity. Our stable, long-term seismic observations enable us to detect SSEs using the recorded earthquake catalog, by considering an earthquake swarm as a proxy for a slow slip episode. Six recurrent episodes are identified in this way since 1982. The average duration of the SSE interoccurrence interval is 68 mo; however, there are significant fluctuations from this mean. While a regular cycle can be explained using a simple physical model, the mechanisms that are responsible for the observed fluctuations are poorly known. Here we show that the latest SSE in the Boso Peninsula was likely hastened by the stress transfer from the March 11, 2011 great Tohoku earthquake. Moreover, a similar mechanism accounts for the delay of an SSE in 1990 by a nearby earthquake. The low stress buildups and drops during the SSE cycle can explain the strong sensitivity of these SSEs to stress transfer from external sources.

scholarly journals Tremor and Inferred Slow Slip Associated With Afterslip of the 2011 Tohoku Earthquake

2019 ◽  
Vol 46 (9) ◽  
pp. 4591-4598 ◽  
Author(s):  
Kazuaki Ohta ◽  
Yoshihiro Ito ◽  
Ryota Hino ◽  
Shukei Ohyanagi ◽  
Takanori Matsuzawa ◽  
...  
Keyword(s):  
Tohoku Earthquake ◽  
2011 Tohoku Earthquake ◽  
Slow Slip ◽  
The 2011 Tohoku Earthquake

scholarly journals An intraplate slow earthquake observed by a dense GPS network in Hokkaido, northernmost Japan

2014 ◽  
Vol 200 (1) ◽  
pp. 144-148 ◽  
Author(s):  
Mako Ohzono ◽  
Hiroaki Takahashi ◽  
Masayoshi Ichiyanagi
Keyword(s):  
Subduction Zones ◽  
Earthquake Swarm ◽  
Tectonic Activity ◽  
Maximum Magnitude ◽  
Slow Slip ◽  
Localized Deformation ◽  
Slow Earthquake ◽  
Magnitude Scaling ◽  
Duration Magnitude ◽  
Slow Earthquakes

Abstract An intraplate slow earthquake was detected in northernmost Hokkaido, Japan, by a dense network of the global navigation satellite system. Transient abnormal acceleration of <12 mm was observed during the period 2012 July to 2013 January (∼5.5 months) at several sites. The spatial displacement distribution suggests that a localized tectonic event caused localized deformation. Estimated fault parameter indicates very shallow-dip reverse faulting in the uppermost crust, with a total seismic moment of 1.75E + 17 N m (Mw 5.4). This fault geometry is probably consistent with detachment structure indicated by geological studies. A simultaneous earthquake swarm with the maximum magnitude M4.1 suggests a possibility that the slow slip triggered the seismic activity for unknown reasons. This slow earthquake is slower than its moment would indicate, with a duration–magnitude scaling relationship unlike either regular earthquakes or subduction slow slip events. This result indicates that even if the area is under different physical property from subduction zones, slow earthquake can occur by some causes. Slow earthquakes exist in remote regions away from subduction zones and might play an important role in strain release and tectonic activity.

scholarly journals Tectonic tremor and deep slow slip on the Alpine Fault

2021 ◽  
Author(s):  
A Wech ◽  
C Boese ◽  
Timothy Stern ◽  
John Townend
Keyword(s):  
Lower Crust ◽  
Subduction Zones ◽  
Plate Boundary ◽  
P Wave ◽  
Plate Boundaries ◽  
Depth Range ◽  
Slow Slip ◽  
High Attenuation ◽  
Alpine Fault ◽  
Tectonic Tremor

Tectonic tremor is characterized by persistent, low-frequency seismic energy seen at major plate boundaries. Although predominantly associated with subduction zones, tremor also occurs along the deep extension of the strike-slip San Andreas Fault. Here we present the first observations of tectonic tremor along New Zealand's Alpine Fault, a major transform boundary that is late in its earthquake cycle. We report tectonic tremor that occurred on the central section of the Alpine Fault on 12days between March 2009 and October 2011. Tremor hypocenters concentrate in the lower crust at the downdip projection of the Alpine Fault; coincide with a zone of high P-wave attenuation (low Q p) and bright seismic reflections; occur in the 25-45km depth range, below the seismogenic zone; and may define the deep plate boundary structure extending through the lower crust and into the upper mantle. We infer this tremor to represent slow slip on the deep extent of the Alpine Fault in a fluid-rich region marked by high attenuation and reflectivity. These observations provide the first indication of present-day displacement on the lower crustal portion of the Australia-Pacific transform plate boundary. © Copyright 2012 by the American Geophysical Union.

scholarly journals Joint estimate of the co-seismic 2011 Tohoku earthquake fault slip and post-seismic viscoelastic relaxation by GRACE data inversion

2019 ◽  
Author(s):  
G Cambiotti
Keyword(s):  
Temporal Resolution ◽  
Subduction Zones ◽  
Gravity Data ◽  
Tohoku Earthquake ◽  
Fault Slip ◽  
2011 Tohoku Earthquake ◽  
The 2011 Tohoku Earthquake ◽  
Physical Constraints ◽  
Megathrust Earthquakes ◽  
Grace Data

SUMMARY Satellite-derived gravity data offer a novel perspective for understanding the physics of megathrust earthquakes at subduction zones. Nonetheless, their temporal resolution and observational errors make it difficult to discern the different phases of the seismic cycle, as the elastostatic deformation (co-seismic) and the stress relaxation by viscous flow (post-seismic). To overcome these difficulties and to take advantage of the physical constraints on the temporal evolution and on the spatial pattern of the earthquake-induced gravity disturbances, we have jointly estimated the fault slip of the 2011 Tohoku earthquake and the rheological stratification by means of a Bayesian inversion of GRACE data time series and within the framework of spherically symmetric self-gravitating compressible viscoelastic Earth models. This approach, in addition to improve the exploitation of satellite-derived gravity data, allows us (i) to constrain the fault slip taking advantage of information from both the co- and post-seismic signatures and (ii) to investigate the trade-off between the fault slip and the shallow rheological stratification. In this respect, it can be used to improve the modelling of crustal displacements from GPS data, even if their higher accuracy and temporal resolution allow to discriminate well the co-seismic signature from the others.

scholarly journals Tectonic tremor and deep slow slip on the Alpine Fault

2021 ◽  
Author(s):  
A Wech ◽  
C Boese ◽  
Timothy Stern ◽  
John Townend
Keyword(s):  
Lower Crust ◽  
Subduction Zones ◽  
Plate Boundary ◽  
P Wave ◽  
Plate Boundaries ◽  
Depth Range ◽  
Slow Slip ◽  
High Attenuation ◽  
Alpine Fault ◽  
Tectonic Tremor

Tectonic tremor is characterized by persistent, low-frequency seismic energy seen at major plate boundaries. Although predominantly associated with subduction zones, tremor also occurs along the deep extension of the strike-slip San Andreas Fault. Here we present the first observations of tectonic tremor along New Zealand's Alpine Fault, a major transform boundary that is late in its earthquake cycle. We report tectonic tremor that occurred on the central section of the Alpine Fault on 12days between March 2009 and October 2011. Tremor hypocenters concentrate in the lower crust at the downdip projection of the Alpine Fault; coincide with a zone of high P-wave attenuation (low Q p) and bright seismic reflections; occur in the 25-45km depth range, below the seismogenic zone; and may define the deep plate boundary structure extending through the lower crust and into the upper mantle. We infer this tremor to represent slow slip on the deep extent of the Alpine Fault in a fluid-rich region marked by high attenuation and reflectivity. These observations provide the first indication of present-day displacement on the lower crustal portion of the Australia-Pacific transform plate boundary. © Copyright 2012 by the American Geophysical Union.

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