Source Model Estimation by Waveform Inversion using One- or Two-Station Strong-Motion Records

Abstract In this study, we investigate the source rupture process of the 2018 Hokkaido Eastern Iburi earthquake in Japan (MJMA 6.7) and how the ground motion can be reproduced using available source and velocity models. First, we conduct a multiple-time-window kinematic waveform inversion using strong-motion waveforms, which indicates that a large-slip area located at a depth of 25–30 km in the up-dip direction from the hypocenter was caused by a rupture propagating upward 6–12 s after its initiation. Moreover, the high-seismicity area of aftershocks did not overlap with the large-slip area. Subsequently, using the obtained source model and a three-dimensional velocity structure model, we conduct a forward long-period (< 0.5 Hz) ground-motion simulation. The simulation was able to reproduce the overall ground-motion characteristics in the sedimentary layers of the Ishikari Lowland.

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Source process of the 2011 off the Pacific coast of Tohoku Earthquake inferred from waveform inversion with long-period strong-motion records

Earth Planets and Space ◽

10.5047/eps.2011.06.050 ◽

2011 ◽

Vol 63 (7) ◽

pp. 577-582 ◽

Cited By ~ 36

Author(s):

Kunikazu Yoshida ◽

Ken Miyakoshi ◽

Kojiro Irikura

Keyword(s):

Pacific Coast ◽

Waveform Inversion ◽

Strong Motion ◽

Tohoku Earthquake ◽

Source Process ◽

Strong Motion Records ◽

Long Period ◽

The Pacific

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Focal mechanism determination and identification of the fault plane of earthquakes using only one or two near-source seismic recordings

Bulletin of the Seismological Society of America ◽

10.1785/bssa0890061558 ◽

1999 ◽

Vol 89 (6) ◽

pp. 1558-1574 ◽

Cited By ~ 4

Author(s):

Bertrand Delouis ◽

Denis Legrand

Keyword(s):

Focal Mechanism ◽

Fault Plane ◽

Epicentral Distance ◽

Near Field ◽

Waveform Inversion ◽

Strong Motion ◽

Source Model ◽

Resolving Power ◽

Fault Parameters ◽

Single Station

Abstract A waveform inversion scheme was developed in order to explore the resolving power of one or two seismic recordings at short epicentral distance for the determination of focal mechanisms and the identification of the fault plane of earthquakes. Two key features are used to constrain the fault parameters with a reduced number of stations: (1) a simple finite-dimension source model and (2) the modeling of the complete displacement field, including the near-field waves. The identification of the fault plane should be possible, even with a single station, as soon as the seismograms produced by the two nodal planes of a same focal mechanism are significantly different, which is the general case when waveforms are controlled by source finiteness. Seven parameters, including the strike, dip, rake, and dislocation, are explored with a grid search, and the minima of the misfit error between the observed and calculated seismograms are mapped. With such an approach, it is possible to conclude about the uniqueness or nonuniqueness of the solutions. The method is tested with three earthquakes of moderate to large size for which the fault plane is well established and for which strong-motion records are available at maximum distances of a few tens of kilometers. Test events are the 1994 Northridge (Mw = 6.7, California), the 1996 Copala (Mw = 7.3, Mexico), and the 1996 Pinotepa Nacional (Mw = 5.4, Mexico) earthquakes. In the case of inversions with two stations, we find a unique solution, or a group of similar solutions, with a good estimation of the focal mechanism and the proper selection of the fault plane. Our results also show that in some cases a single station may be enough to recover the fault parameters. The inversion scheme presented here may be systematically applied to future earthquakes, especially to those recorded by few stations. It should be particularly useful in the case of blind faults for which the fault plane may not be identified with the help of other data.

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