There are several active faults within the region (Fig. It is the heart of the Osaka–Kobe–Kyoto urban area (i.e., the second-most populated region in Japan), and it has a remarkable role in the global economy. The Osaka metropolitan area consists of a population exceeding eight million and is the economical center of western Japan. In total, JMA unified hypocenter catalog for Japan comprises 2140 local events of M JMA ≥ 0.5 in the period June 18–J(see bottom panel in Fig. The mainshock was followed by a sequence of weaker aftershocks not exceeding M JMA4.1. The centroid moment tensor (CMT) has compressional P-axis along the ESE–WNW direction, and it contains large non-shear components. The source mechanism of this earthquake has been routinely investigated by JMA, National Research Institute for Earth Science and Disaster Resilience (NIED) and other agencies (see Table 1). There is no observed surface rupture, and no significant surface deformation was reported by InSAR analysis. The maximum measured peak ground acceleration (PGA) exceeded 0.9 g, and the instrumental intensity in the epicentral area reached a degree 6-lower of the 7-degree JMA scale. The earthquake damage and response are briefly summarized in Hirata and Kimura ( 2018). This event generated strong ground motions in the near-source region, causing damage on a local scale and four casualties. The hypocenter was located by the Japan Meteorological Agency (JMA) at a depth of 13 km under Takatsuki city (34.844°N, 135.622☎) in the Osaka metropolitan area, Kansai, Japan (see Fig. The 2018 northern Osaka earthquake mainshock–aftershocks sequence was started on J(07:58 of Japan Standard Time), by an M JMA6.1 mainshock. Joint shear movements on both of these faults contributed significantly to the total seismic moment of the mainshock. The activated N–S reverse fault is dipping to east by 50° similarly as the Uemachi fault system. To conclude, the activated strike-slip fault is parallel to the Arima-Takatsuki Tectonic Line. Both ENE–WSW dextral strike-slip and N–S reverse faults can be active in such stress field as observed in the mainshock (without any need for stress spatial inhomogeneity). The local stress field inverted from these mechanisms had a dominant maximum (compressional) principal stress σ 1 in ESE–WNW direction, while σ 2 ≅ σ 3. Aftershocks’ moment tensors inverted from P-wave amplitudes exhibit mainly strike-slip and reverse faulting mechanisms, having significant spatial variations. We also analyzed the 108 strongest aftershocks with M JMA between 2.0 and 4.1 using records from broadband and short-period stations. Decomposition of the non-DC moment tensor into major and minor pure-shear moment tensors suggests a combination of strike-slip and reverse faulting mechanisms. The solution of M w5.6 involved a significant CLVD component, which we interpreted as being due to rupture process on a complex fault geometry. In particular, we infer to a centroid moment tensor for the mainshock using Bayesian full-waveform inversion from strong motion records. Here we propose a seismotectonic model of this sequence based on seismological data and stress field considerations. The earthquakes were located near the Arima-Takatsuki Tectonic Line (ENE–WSW dextral strike-slip faults) and the Uemachi fault system (N–S reverse faults), hence the seismotectonic interpretations we assumed to be rather complex. This event impacted the region by the maximum PGA larger than 0.9 g, and it was followed by a series of weaker aftershocks. P/S: Check out the Resources page for our recommended courses and lessons.On June 18, 2018, an M JMA6.1 inland crustal earthquake occurred on the northeast edge of the Osaka basin, Japan. Listen to (and repeat) each lesson many times - and watch how fast your English speaking improves! Each lesson consists of the definition (meaning) of the word, the audio pronunciation, and many example sentences with high-quality audio. In the following section, you will find around 3000 free lessons for the 3000 most commonly used words in English. FREE English Lessons - 3000 Most Frequently Used Words in English This is how you will achieve automatically fast speaking. You must listen to that example sentence again and again.ĭon't ignore this simple secret. If the answer is no, you need to repeat more. You may know how to use a word to make a correct sentence, but here's the thing: Can you use it quickly, easily, and automatically? Don't listen just one time or a few times. It means that you will need to listen to every example sentence many, many times, until you MASTER it. If you want to quickly achieve fluency level - to speak English easily, fluently and automatically, you'll need to do one more thing: Repetition is the secret to English fluency
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