Inchworm-like source evolution through a geometrically complex fault fueled persistent supershear rupture during the 2018 Palu Indonesia earthquake

Okuwaki, Ryo; Hirano, Shiro; Yagi, Y.; Shimizu, Keiko

doi:10.1016/j.epsl.2020.116449

Cited by 27 publications

(21 citation statements)

References 49 publications

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“…The transitions of fault geometry associated with lower potency‐rate density correspond with the area of aftershocks of the 2020 Caribbean earthquake between about 140 and 200 km west of the epicenter (Figure 2). Geometrical complexity in earthquake fault, including a fault bend, can affect the fluctuation of rupture propagation (Okuwaki et al., 2020; Ulrich et al., 2019). Simulations of dynamic fault rupture on strike‐slip fault systems have demonstrated that an unfavorably oriented fault bend can reduce both the amount of displacement and the rupture speed (Bruhat et al., 2016; Duan & Oglesby, 2005; Kase & Day, 2006).…”

Section: Discussionmentioning

confidence: 99%

Rupture Process of the 2020 Caribbean Earthquake Along the Oriente Transform Fault, Involving Supershear Rupture and Geometric Complexity of Fault

Tadapansawut

Okuwaki

Yagi

et al. 2021

Geophysical Research Letters

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Section: Discussionmentioning

confidence: 99%

Rupture Process of the 2020 Caribbean Earthquake Along the Oriente Transform Fault, Involving Supershear Rupture and Geometric Complexity of Fault

Tadapansawut

Okuwaki

Yagi

et al. 2021

Geophysical Research Letters

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“…The earthquake source model is constructed based on the finite-fault inversion method developed by Shimizu et al (2020), which has been an efficient tool for robustly estimating the complex rupture evolution of earthquakes (e.g., Okuwaki et al, 2020;Shimizu et al, 2020;Tadapansawut et al, 2021). This method is based on reducing the modelling errors associated with uncertainties in Green's function calculations (Yagi & Fukahata, 2011) and fault geometries (Shimizu et al, 2020).…”

Section: Methodsmentioning

confidence: 99%

Long Tsunami Oscillations Following the 30 October 2020 Mw 7.0 Aegean Sea Earthquake: Observations and Modelling

Heidarzadeh

Pranantyo

Okuwaki

et al. 2021

Pure Appl. Geophys.

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Eastern Mediterranean Sea has experienced four tsunamigenic earthquakes since 2017, which delivered moderate damage to coastal communities in Turkey and Greece. The most recent of these tsunamis occurred on 30 October 2020 in the Aegean Sea, which was generated by an Mw 7.0 normal-faulting earthquake, offshore Izmir province (Turkey) and Samos Island (Greece). The earthquake was destructive and caused death tolls of 117 and 2 in Turkey and Greece, respectively. The tsunami produced moderate damage and killed one person in Turkey. Due to the semi-enclosed nature of the Aegean Sea basin, any tsunami perturbation in this sea is expected to trigger several basin oscillations. Here, we study the 2020 tsunami through sea level data analysis and numerical simulations with the aim of further understanding tsunami behavior in the Aegean Sea. Analysis of data from available tide gauges showed that the maximum zero-to-crest tsunami amplitude was 5.1–11.9 cm. The arrival times of the maximum tsunami wave were up to 14.9 h after the first tsunami arrivals at each station. The duration of tsunami oscillation was from 19.6 h to > 90 h at various tide gauges. Spectral analysis revealed several peak periods for the tsunami; we identified the tsunami source periods as 14.2–23.3 min. We attributed other peak periods (4.5 min, 5.7 min, 6.9 min, 7.8 min, 9.9 min, 10.2 min and 32.0 min) to non-source phenomena such as basin and sub-basin oscillations. By comparing surveyed run-up and coastal heights with simulated ones, we noticed the north-dipping fault model better reproduces the tsunami observations as compared to the south-dipping fault model. However, we are unable to choose a fault model because the surveyed run-up data are very limited and are sparsely distributed. Additional researches on this event using other types of geophysical data are required to determine the actual fault plane of the earthquake.

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“…Therefore, we conclude that the rupture evolution of the 2014 Thailand earthquake is characterized by multiple sub-events in the conjugated strike-slip fault system of the PF and MLF. Furthermore, studies using the flexible teleseismic finite-fault inversion have shown that complexities in the faulting system, like geometric bends, can cause the non-smooth rupture propagation of the mainshock (e.g., Okuwaki et al, 2020;Tadapansawut et al, 2021;Yamashita et al, 2021). The dynamic rupture simulation demonstrates that rupture perturbation could have occurred from the bend along a strike-slip faulting (Duan & Oglesby, 2005;Kase & Day, 2006).…”

Section: Discussionmentioning

confidence: 99%

Complex rupture process of the 2014 Thailand Mw 6.2 earthquake on the conjugate fault system of the Phayao fault zone

Tadapansawut¹,

Yagi²,

Okuwaki³

et al. 2021

Preprint

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The earthquake with a moment magnitude 6.2 that occurred in northern Thailand on 5 May 2014 is the largest recorded in Thailand by modern seismographs; the source is located in the multi-segmented complex fault system of the Phayao fault zone in the northern Thai province of Chiang Rai. This geological setting is appropriate environment for investigating a compound rupture process associated with a geometrically complex fault system in a magnitude-6-class earthquake. To understand in detail the rupture process of the 2014 Thailand earthquake, we elaborate the flexible finite-fault inversion method, used it to invert the globally-observed teleseismic P waveforms, and resolved for the spatiotemporal distribution of both the slip and the fault geometry. The complex rupture process consists of two distinct coseismic slip episodes that evolved along two discontinuous fault planes; these planes coincide with the lineations of the aftershock distribution. The first episode originated at the hypocenter and the rupture propagated south along the north-northeast to south-southwest fault plane. The second episode was triggered at around 5 km north from the epicenter and the rupture propagated along the east-northeast to west-southwest fault plane and terminated at the west end of the source area at 4.5 s hypocentral time. The fault system derived from our finite-fault model suggests geometric complexities including bends. The derived spatiotemporal orientation of the principal stress axis shows different lineations within the two rupture areas and heterogeneity at their edges. This geological setting may have caused the perturbation of the rupture propagation and the triggering of the distinct rupture episodes. Our source model of the 2014 Thailand earthquake suggests that even in the case of small-scale earthquakes, the rupture evolution can be complex when the underlying fault geometry is multiplex.

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Inchworm-like source evolution through a geometrically complex fault fueled persistent supershear rupture during the 2018 Palu Indonesia earthquake

Cited by 27 publications

References 49 publications

Rupture Process of the 2020 Caribbean Earthquake Along the Oriente Transform Fault, Involving Supershear Rupture and Geometric Complexity of Fault

Rupture Process of the 2020 Caribbean Earthquake Along the Oriente Transform Fault, Involving Supershear Rupture and Geometric Complexity of Fault

Long Tsunami Oscillations Following the 30 October 2020 Mw 7.0 Aegean Sea Earthquake: Observations and Modelling

Complex rupture process of the 2014 Thailand Mw 6.2 earthquake on the conjugate fault system of the Phayao fault zone

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