Time and Space Distribution of Coseismic Slip of the 2011 Tohoku Earthquake as Inferred from Tsunami Waveform Data

2013 ◽  
Vol 103 (2B) ◽  
pp. 1473-1492 ◽  
Author(s):  
K. Satake ◽  
Y. Fujii ◽  
T. Harada ◽  
Y. Namegaya
Keyword(s):  
Tohoku Earthquake ◽  
2011 Tohoku Earthquake ◽  
Space Distribution ◽  
Time And Space ◽  
Coseismic Slip ◽  
The 2011 Tohoku Earthquake ◽  
Waveform Data ◽  
Tsunami Waveform

scholarly journals Changes in the b value in and around the focal areas of the M6.9 and M6.8 earthquakes off the coast of Miyagi prefecture, Japan, in 2021

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
K. Z. Nanjo ◽  
A. Yoshida
Keyword(s):  
Source Region ◽  
High Stress ◽  
Tohoku Earthquake ◽  
B Value ◽  
2011 Tohoku Earthquake ◽  
East Side ◽  
Coseismic Slip ◽  
The 2011 Tohoku Earthquake ◽  
Value Analysis ◽  
Miyagi Prefecture

AbstractWe investigated changes in the b value of the Gutenberg–Richter’s law in and around the focal areas of earthquakes on March 20 and on May 1, 2021, with magnitude (M) 6.9 and 6.8, respectively, which occurred off the Pacific coast of Miyagi prefecture, northeastern Japan. We showed that the b value in these focal areas had been noticeably small, especially within a few years before the occurrence of the M6.9 earthquake in its vicinity, indicating that differential stress had been high in the focal areas. The coseismic slip of the 2011 Tohoku earthquake seems to have stopped just short of the east side of the focus of the M6.9 earthquake. Furthermore, the afterslip of the 2011 Tohoku earthquake was relatively small in the focal areas of the M6.9 and M6.8 earthquakes, compared to the surrounding regions. In addition, the focus of the M6.9 earthquake was situated close to the border point where the interplate slip in the period from 2012 through 2021 has been considerably larger on the northern side than on the southern side. The high-stress state inferred by the b-value analysis is concordant with those characteristics of interplate slip events. We found that the M6.8 earthquake on May 1 occurred near an area where the b value remained small, even after the M6.9 quake. The ruptured areas by the two earthquakes now seem to almost coincide with the small-b-value region that had existed before their occurrence. The b value on the east side of the focal areas of the M6.9 and M6.8 earthquakes which corresponds to the eastern part of the source region of the 1978 off-Miyagi prefecture earthquake was consistently large, while the seismicity enhanced by the two earthquakes also shows a large b value, implying that stress in the region has not been very high.

scholarly journals Seismic Reflection Images of Possible Mantle-Fluid Conduits and Basal Erosion in the 2011 Tohoku Earthquake Rupture Area

2021 ◽  
Vol 9 ◽  
Author(s):  
Jin-Oh Park ◽  
Tetsuro Tsuru ◽  
Gou Fujie ◽  
Ehsan Jamali Hondori ◽  
Takanori Kagoshima ◽  
...  
Keyword(s):  
Seismic Reflection ◽  
Mantle Wedge ◽  
Tohoku Earthquake ◽  
High Amplitude ◽  
2011 Tohoku Earthquake ◽  
Normal Faults ◽  
Reverse Polarity ◽  
Coseismic Slip ◽  
The 2011 Tohoku Earthquake ◽  
Middle Slope

Multi-channel seismic reflection and sub-bottom profiling data reveal landward-dipping normal faults as potential conduits for mantle-derived fluids in the coseismic slip area of the 2011 Tohoku earthquake (Mw9.0). Normal faults below the helium isotope anomaly sites appear to develop through the forearc crust (i.e., the seafloor sedimentary section and Cretaceous basement) and to evolve to lower dip angles as extension progresses deeper, potentially extending down to the mantle wedge, despite their intermittently continuous reflections. The faults are characterized by high-amplitude, reverse-polarity reflections within the Cretaceous basement. Moreover, deep extension of the faults connecting to a low-velocity region spreading from the Cretaceous basement into the mantle wedge across the forearc Moho suggests that the faults are overpressured by local filling with mantle-derived fluids. The locations of the normal faults are roughly consistent with aftershocks of the 2011 Tohoku earthquake, which show normal-faulting focal mechanisms. The 2011 Tohoku mainshock and subsequent aftershocks can lead the pre-existing normal faults to be reactive and more permeable so that locally trapped mantle fluids can migrate up to the seafloor through fault fracture zones. The reactivated normal faults may be an indicator of shallow coseismic slip to the trench. Locally elevated fluid pressures can decrease the effective normal stress for the fault plane, facilitating easier slip along the fault and local tsunami. The landward-dipping normal faults developing from the seafloor down into the Cretaceous basement are predominant in the middle slope region of the forearc. A possible shear zone with high-amplitude, reverse-polarity reflections above the plate interface, which is almost localized to the middle slope region, suggests more intense basal erosion of the overlying plate in that region.

Analysis of traveling ionospheric disturbances (TIDs) in GPS TEC launched by the 2011 Tohoku earthquake

Radio Science ◽  
2016 ◽  
Vol 51 (5) ◽  
pp. 507-514 ◽  
Author(s):  
Geoff Crowley ◽  
Irfan Azeem ◽  
Adam Reynolds ◽  
Timothy M. Duly ◽  
Patrick McBride ◽  
...  
Keyword(s):  
Tohoku Earthquake ◽  
2011 Tohoku Earthquake ◽  
Ionospheric Disturbances ◽  
The 2011 Tohoku Earthquake ◽  
Gps Tec ◽  
Traveling Ionospheric Disturbances

Tsunami source of the 2011 Tohoku earthquake detected by an ocean-bottom magnetometer

2013 ◽  
Vol 382 ◽  
pp. 117-124 ◽  
Author(s):  
Hiroshi Ichihara ◽  
Yozo Hamano ◽  
Kiyoshi Baba ◽  
Takafumi Kasaya
Keyword(s):  
Tohoku Earthquake ◽  
2011 Tohoku Earthquake ◽  
Tsunami Source ◽  
Ocean Bottom ◽  
The 2011 Tohoku Earthquake
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