Characterized source model of the 2023 Mw 7.6 Turkey earthquake for strong motion prediction of crustal mega-earthquakes
摘要
The 2023 Mw 7.6 Turkey earthquake was a crustal mega-earthquake that caused severe damage and loss of life. However, previous slip models based on kinematic source inversion or back-projection are not applicable to simulate or predict strong ground motions in the full frequency range of engineering interest. In this study, a characterized source model of the 2023 Mw 7.6 Turkey earthquake was estimated by the empirical Green’s function method using near-field strong motion records over a frequency range of 0.2–10 Hz. Among five strong motion generation areas (SMGAs) of the estimated model, the one with the largest Brune stress drop of 24.2 MPa was close to the large slip area estimated by previous slip models. Another SMGA was located near the fault bend, and two more SMGAs were located near the end of the faults where off-fault deformation was large. In both locations, the slip was not as large as in previous models. The off-fault damage may have facilitated high-frequency motion near the end of the fault. It is also conceivable that the fault bend acted as a geometric barrier, generating high-frequency ground motions. Bilateral supershear rupture was estimated to occur on both sides of the hypocenter. Short-period spectral level, which is the constant value of the acceleration source spectrum higher than the corner frequency, was larger than the previous scaling relations and data of five Mw > 7.4 crustal mega-earthquakes, including the 2023 Mw 7.8 Turkey earthquake. The combined area of the SMGAs were comparable to them. These results indicate that the Mw 7.6 Turkey earthquake generated more high-frequency motions compared to previous crustal mega-earthquakes. The short-period spectral level and the combined area of the SMGAs of the Mw 7.6 Turkey earthquake estimated in this study will be useful to improve their scaling relations of crustal mega-earthquakes for strong motion prediction.
Graphical abstract