The 2016 Kumamoto–Oita earthquake sequence: aftershock seismicity gap and dynamic triggering in volcanic areas

Uchide, Takahiko; Horikawa, Haruo; Nakai, Misato; Matsushita, Reiken; Shigematsu, Norio; Ando, Ryosuke; Imanishi, Kazutoshi

doi:10.1186/s40623-016-0556-4

Cited by 57 publications

(76 citation statements)

References 43 publications

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“…The magnitude is obtained using amplitude data from only two stations near the hypocenter and therefore also has a high uncertainty. The hypocenter and magnitude are consistent with those obtained by other studies (e.g., Nakamura and Aoi 2016; Uchide et al 2016;Yoshida 2016), where the hypocenters are located within an error range of ~1 km using different velocity models, and the moment magnitude or local magnitude ranges from 5.6 to 6.5.…”

Section: Location Of the Triggered Oita Earthquake And Estimation Of supporting

confidence: 79%

An investigation into the remote triggering of the Oita earthquake by the 2016 Mw 7.0 Kumamoto earthquake using full wavefield simulation

Miyazawa

2016

Earth Planets Space

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High-amplitude seismic waves from the Mw 7.0 Kumamoto earthquake of April 16, 2016, triggered another large earthquake 80 km to the NE roughly 30 s later. The source was located at shallow depths beneath the Yufuin geothermal field, Oita Prefecture, Japan, and the event magnitude was approximately 5.9. To date, this is one of the clearest known examples of a remotely triggered large earthquake. The triggered Oita event was followed by significant seismicity, which was distinct from the aftershocks of the Kumamoto earthquake. The Coulomb failure stress change around the hypocenter, calculated for the passing waves of the Kumamoto earthquake by full wavefield simulation, was about 0.7 MPa when the Oita earthquake was triggered, with the static stress change being an order of magnitude smaller. The dynamic stress changes likely played an important role in triggering. A return to low seismicity levels 1 month after the triggered earthquake may have important implications for seismic hazard due to dynamic triggering.

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Section: Location Of the Triggered Oita Earthquake And Estimation Of supporting

confidence: 79%

An investigation into the remote triggering of the Oita earthquake by the 2016 Mw 7.0 Kumamoto earthquake using full wavefield simulation

Miyazawa

2016

Earth Planets Space

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“…Determining the fault plane dip direction based on the aftershock distribution is difficult because of the seismicity gap in the western part of the Aso caldera region (Aso gap in Fig. 1, Uchide et al 2016). Although we have previously proposed a source model with a northwestdipping fault model using strong-motion data (Irikura et al 2017), it is important to rediscuss a source model with a southeast-dipping fault model based on strong motion.…”

Section: Introductionmentioning

confidence: 99%

Source process of the 2016 Kumamoto earthquake (Mj7.3) inferred from kinematic inversion of strong-motion records

Yoshida¹,

Miyakoshi²,

Somei³

et al. 2017

Earth Planets Space

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In this study, we estimated source process of the 2016 Kumamoto earthquake from strong-motion data by using the multiple-time window linear kinematic waveform inversion method to discuss generation of strong motions and to explain crustal deformation pattern with a seismic source inversion model. A four-segment fault model was assumed based on the aftershock distribution, active fault traces, and interferometric synthetic aperture radar data. Three western segments were set to be northwest-dipping planes, and the most eastern segment under the Aso caldera was examined to be a southeast-dipping plane. The velocity structure models used in this study were estimated by using waveform modeling of moderate earthquakes that occurred in the source region. We applied a two-step approach of the inversions of 20 strong-motion datasets observed by K-NET and KiK-net by using band-pass-filtered strong-motion data at 0.05-0.5 Hz and then at 0.05-1.0 Hz. The rupture area of the fault plane was determined by applying the criterion of Somerville et al. (Seismol Res Lett 70:59-80, 1999) to the inverted slip distribution. From the first-step inversion, the fault length was trimmed from 52 to 44 km, whereas the fault width was kept at 18 km. The trimmed rupture area was not changed in the second-step inversion. The source model obtained from the two-step approach indicated 4.7 × 10 19 Nm of the total moment release and 1.8 m average slip of the entire fault with a rupture area of 792 km 2 . Large slip areas were estimated in the seismogenic zone and in the shallow part corresponding to the surface rupture that occurred during the Mj7.3 mainshock. The areas of the high peak moment rate correlated roughly with those of large slip; however, the moment rate functions near the Earth surface have low peak, bell shape, and long duration. These subfaults with long-duration moment release are expected to cause weak short-period ground motions. We confirmed that the southeast dipping of the most eastern segment is more plausible rather than northwest-dipping from the observed subsidence around the central cones of the Aso volcano.

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“…Buildings in Kumamoto city and the neighboring Mashikimachi town incurred severe damage [25]. The main deformation occurred 40 km along the Futagawa and Hinagu faults from south-west to north-east [28].…”

Section: Kumamoto Japan Earthquakes and Alos-2 Observationsmentioning

confidence: 99%

“…The analytical results for the 2016 Kumamoto, Japan earthquakes [27,28] were compared with two independent observations. The first observation throughout a central urban area of Kumamoto considering a larger scale includes the aerial photography for counting the damaged buildings which are covered with plastic sheets.…”

Section: Introductionmentioning

confidence: 99%

Sensitivity and Limitation in Damage Detection for Individual Buildings Using InSAR Coherence—A Case Study in 2016 Kumamoto Earthquakes

et al. 2018

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Abstract:In this paper, evaluation results are presented for multi-temporal interferometric coherence analysis using a Synthetic Aperture Radar (SAR) for damage assessment in an urban area. The latest space-borne SARs potentially have a high enough spatial resolution to assess individual buildings. However, interferometric coherence analysis has not been evaluated for its limitation in sensitivity and size of damaged buildings. In particular, the correlation between the coherence analysis and the damage level referred to by architectural assessments has been an open question. In this paper, analytical results using ALOS-2 PALSAR-2 datasets are presented from the 2016 Kumamoto earthquakes in Japan. For reference, building damage was assessed throughout the central urban area and specifically at a catastrophically damaged district. The results show that the buildings should be larger than a window size of the coherence for damage detection, and the damage level should be larger than Level-2 of 5, classified with the European Macroseismic Scale 1998 (EMS-98).

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The 2016 Kumamoto–Oita earthquake sequence: aftershock seismicity gap and dynamic triggering in volcanic areas

Cited by 57 publications

References 43 publications

An investigation into the remote triggering of the Oita earthquake by the 2016 Mw 7.0 Kumamoto earthquake using full wavefield simulation

An investigation into the remote triggering of the Oita earthquake by the 2016 Mw 7.0 Kumamoto earthquake using full wavefield simulation

Source process of the 2016 Kumamoto earthquake (Mj7.3) inferred from kinematic inversion of strong-motion records

Sensitivity and Limitation in Damage Detection for Individual Buildings Using InSAR Coherence—A Case Study in 2016 Kumamoto Earthquakes

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