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Estimation of the Fault Constitutive Parameter Aσ and Stress Accumulation Rate from Seismicity Response to a Large Earthquake. Kenji MAEDA Meteorological Research Institute, JMA. Objectives. Estimate the fault constitutive parameter A σ from the seismicity response to a large earthquake.
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Estimation of the Fault Constitutive Parameter Aσ and Stress Accumulation Rate from Seismicity Response to a Large Earthquake Kenji MAEDA Meteorological Research Institute, JMA
Objectives • Estimate the fault constitutive parameter Aσ from the seismicity response to a large earthquake. • Estimate the stress accumulation rate from the seismicity response to a large earthquake. • Estimate the stress change from seismicity data.
Seismicity rate after the stress step Dieterich(1994)
Seismicity rate after the stress step Dieterich(1994)
When we select the target area to apply the method, we pay attention to • The fault model of a large earthquake is well determined. • The seismicity rate change caused by a stress step is clearly recognized. • The area is far enough from a large earthquake not to be effected by a slip inhomogeneity of the earthquake. • The rate change tend to follow Omori’s formula.
dCFF by the 2003 Tokachi-oki Eq. 0.07~0.16MPa
Space-Time Distribution of Eqs. D C B A 2003 Tokachi-oki Eq. (M8.0)
Investigated Regions A B D C
Region A (No decluster) Space-Time 2003 Tokachi-oki Eq. (M8.0) Depth-Time Cumulative
Space Space Connection Distance Cluster 1 Connection Time Cluster 2 Time Time Declustering Algorithm
Region A (Decluster 1km,1day) Space-Time 2003 Tokachi-oki Eq. (M8.0) Depth-Time Cumulative
Region C (No Decluster) Space-Time 2003 Tokachi-oki Eq. (M8.0) Depth-Time Cumulative
Region C (Decluster 3km,7day) Space-Time 2003 Tokachi-oki Eq. (M8.0) Depth-Time Cumulative
Obtaining Stress Change from Seismicity Rate Change Dieterich(2000)
Teshio Shintoku2 Horizontal Movement (1/1/03~2/28/05) GPS data from GSI
Baseline Length Change Between Teshio and Shintoku2 基線長変化 GPS data from GSI Estimated Stress Change in region A Baseline Length and Estimated Stress
Non-declustered Seismicity Estimated Stress Non-declustered Seismicity Change and Estimated Stress
Summary • The fault constitutive parameter Aσ is estimated from the declustered seismicity that is activated by a large earthquake. • The reference stress accumulation rate is also estimated by assuming no large stress change followed the mainshock. • The time variation of stress is estimated from the seismicity rate change by using estimated Aσ and stress accumulation rate .