Abstract
Abstract An Ms7.0 earthquake occurred in Jiuzhaigou, Sichuan Province, China, on August 8, 2017. In this study, we used the vertical component data from 31 seismic stations near the epicenter from May 1 to August 20, 2017, to calculate the amplitude spectrum hourly using the fast Fourier transform method. Furthermore, the spectral area of the low frequency band (0.02–1 Hz), which represents the energy of low frequency motion, was calculated. In this way, the temporal and spatial variations in the vertical ground motion in this region were determined. Four high-value processes occurred in mid-June, mid-July, late July, and early August (the last three are discussed in this article). Based on a comparison with the local meteorological data, the meteorological factors had no influence, local geological factors did not affect the results, and typhoon factors did not show obvious correlation. Combined with the results of previous studies, we believe that the increase in the spectral area reflects the intense movement of deep material in the region related to the Jiuzhaigou earthquake. The spatial distribution of the spectral area (energy) reveals that the deep material moved eastward rapidly, was obstructed by the Sichuan Basin, and expanded to the northwest in a U-shaped channel, which may be the main dynamic factor for the formation or triggering of the earthquake.
Highlights
On August 8, 2017, at 21:49:24, an Ms7.0 earthquake (33.14°N, 103.79°E) occurred in Jiuzhaigou County, Sichuan Province, China, with a focal depth of 20 km
The earthquake was located in the northeastern margin of the Bayan Hara block, which is surrounded by the eastern segment of the East Kunlun Fault, the Longriba Fault, the Minjiang Fault, the Huya Fault, and the Tazang Fault
Based on the distribution of the aftershocks, the orientation of the long axis of the intensity determined from the field investigation, and the investigation of the collapses and landslides caused by the earthquake, several studies have pointed out that the seismogenic fault of this earthquake should be the northward extension of the Huya Fault, which is a left-lateral strike-slip fault, and the fracture process occurred upward from depth [1,2,3]
Summary
On August 8, 2017, at 21:49:24, an Ms7.0 earthquake (33.14°N, 103.79°E) occurred in Jiuzhaigou County, Sichuan Province, China, with a focal depth of 20 km (http://news.ceic.ac.cn/CC201808211947.html). Based on the distribution of the aftershocks, the orientation of the long axis of the intensity determined from the field investigation, and the investigation of the collapses and landslides caused by the earthquake, several studies have pointed out that the seismogenic fault of this earthquake should be the northward extension of the Huya Fault, which is a left-lateral strike-slip fault, and the fracture process occurred upward from depth [1,2,3]. On the southern side of the Bayan Hara block, the southeastward middle-lower crustal flow was obstructed and turned southward in the Luding-Shimian area. This study shows that the crustal flow in the middle and lower crust is diverted into the upward and downward branches after being obstructed by the Sichuan Basin, and it intrudes into the upper crust [5]. As for the dynamic background of the earthquake, it is generally believed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
