Strong Motion Records of the 2011 Tohoku Earthquake and its Attenuation Characteristics

2012 ◽  
Vol 7 (6) ◽  
pp. 693-700 ◽  
Author(s):  
Saburoh Midorikawa ◽  
◽  
Hiroyuki Miura ◽  
Tomohiro Atsumi
Keyword(s):  
Ground Motion ◽  
Strong Motion ◽  
Tohoku Earthquake ◽  
Distribution Model ◽  
Motion Generation ◽  
The 2011 Tohoku Earthquake ◽  
Strong Motion Records ◽  
Attenuation Relationships ◽  
Shortest Distance ◽  
Definition Of

Many strong motion records were obtained during the 2011 Off the Pacific Coast of Tohoku earthquake owing to the implementation of dense strong motion observation in Japan. The earthquake provides an opportunity to examine the characteristics of strong ground motion from a gigantic earthquake. Attenuations of peak acceleration and velocity are examined by comparing them to curves from existing attenuation relationships. When the shortest distance from the fault plane of the slip distribution model is used, curves for Mw8.0 to 8.3 give the smallest deviation from data, suggesting the saturation of ground motion intensity at large magnitudes. When the shortest distance from the strong motion generation areas is used, however, the scattering of data becomes smaller and the curve for Mw9.0 fits acceleration data. Results thus change with the definition of distance. This suggests that a consideration of the rupture heterogeneity is important in strong motion prediction for gigantic earthquakes.

Too-Late Warnings by Estimating Mw: Earthquake Early Warning in the Near-Fault Region

2020 ◽  
Vol 110 (3) ◽  
pp. 1276-1288
Author(s):  
Mitsuyuki Hoshiba
Keyword(s):  
Real Time ◽  
Ground Motion ◽  
Early Warning ◽  
Strong Motion ◽  
Earthquake Early Warning ◽  
Motion Generation ◽  
Near Fault ◽  
Time Gap ◽  
Fault Region ◽  
Strong Ground

ABSTRACT Earthquake early warning (EEW) systems aim to provide advance warnings of impending strong ground shaking. Many EEW systems are based on a strategy in which precise and rapid estimates of source parameters, such as hypocentral location and moment magnitude (Mw), are used in a ground-motion prediction equation (GMPE) to predict the strength of ground motion. For large earthquakes with long rupture duration, the process is repeated, and the prediction is updated in accordance with the growth of Mw during the ongoing rupture. However, in some regions near the causative fault this approach leads to late warnings, because strong ground motions often occur during earthquake ruptures before Mw can be confirmed. Mw increases monotonically with elapsed time and reaches its maximum at the end of rupture, and ground motion predicted by a GMPE similarly reaches its maximum at the end of rupture, but actual generation of strong motion is earlier than the end of rupture. A time gap between maximum Mw and strong-motion generation is the first factor contributing to late warnings. Because this time gap exists at any point of time during the rupture, a late warning is inherently caused even when the growth of Mw can be monitored in real time. In the near-fault region, a weak subevent can be the main contributor to strong ground motion at a site if the distance from the subevent to the site is small. A contribution from a weaker but nearby subevent early in the rupture is the second factor contributing to late warnings. Thus, an EEW strategy based on rapid estimation of Mw is not suitable for near-fault regions where strong shaking is usually recorded. Real-time monitoring of ground motion provides direct information for real-time prediction for these near-fault locations.

A study on amplification response of soil ground motion in Shanghai using strong motion records

2002 ◽  
Vol 15 (6) ◽  
pp. 691-695
Author(s):  
Yong-lin Xu ◽  
Li-jun Xiong ◽  
Chun Zhang ◽  
Zhi-guang Zhao
Keyword(s):  
Ground Motion ◽  
Strong Motion ◽  
Strong Motion Records
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