RED-ACT: 6月24日日本千叶县5.5级地震破坏力分析
RED-ACT Report
Real-time Earthquake Damage Assessment using City-scale Time-history analysis
June 24, M5.5 Japan Chiba-ken Earthquake
Research group of Xinzheng Lu at Tsinghua University (luxz@tsinghua.edu.cn)
First reported at 08:20, June 24, 2019 (Beijing Time, UTC +8)
Acknowledgments and Disclaimer
The authors are grateful for the data provided by K-NET and KiK-net. This analysis is for research only. The actual damage resulting from the earthquake should be determined according to the site investigation.
Scientific background of this report can be found at:
http://www.luxinzheng.net/rr.htm
1. Introduction to the earthquake event
At 09:11 24 Jun 2019 (Local Time, UTC +9), an M 5.5 (JMA) earthquake occurred in Japan Chiba-ken. The epicenter was located at 140.0 34.9, with a depth of 60.0 km.
2. Recorded ground motions
20 ground motions near to epicenter of this earthquake were analyzed. The names and locations of the stations can be found Table 1. The maximal recorded peak ground acceleration (PGA) is 107 cm/s/s. The corresponding response spectra in comparison with the design spectra specified in the Chinese Code for Seismic Design of Buildings are shown in Figure 1.




Figure 1 Response spectra of the recorded ground motions with maximal PGA
3. Damage analysis of the target region subjected to the recorded ground motions
Using the real-time ground motions obtained from the strong motion networks and the city-scale nonlinear time-history analysis (see the Appendix of this report), the damage ratios of buildings located in different places can be obtained. The building damage distribution and the human uncomfortableness distribution near to different stations is shown in Figure 2 and Figure 3, respectively. These outcomes can provide a reference for post-earthquake rescue work.

Figure 2 Damage ratio distribution of the buildings near to different stations

Figure 3 Human uncomfortableness distribution near to different stations
4. Earthquake-induced landslide of the target region subjected to the recorded ground motions
According to local topographic data, lithology data and ground motion records, the distribution of earthquake-induced landslide near to different stations under the different proportions of the landslide slab thickness that is saturated can be calculated, as shown in Figure 4. The basemap shows the distribution of the local slope. The number in the circle represents the critical slope of the landslide. The earthquake-induced landslide tends to occur with a higher probability when the slope near the station is larger than this threshold value.

(a)The proportion of the landslide slab thickness that is saturated equals 0%

(b)The proportion of the landslide slab thickness that is saturated equals 50%

(c)The proportion of the landslide slab thickness that is saturated equals 90%
Figure 4 Distribution of earthquake-induced landslide near to different stations
Scientific background of this report can be found at: http://www.luxinzheng.net/rr.htm
Table 1 Names and locations of the strong motion stations
No.Station NameLongitudeLatitude
1CHB014140.04935.4769
2CHB015139.91635.3738
3CHB017140.07635.2988
4CHB018140.32235.1577
5CHB019139.83535.1105
6CHB021139.89834.9083
7CHB022139.8635.3083
8KNG001139.70635.5291
9KNG002139.63435.4371
10KNG004139.62235.1441
11KNG009139.36235.4424
12SZO001139.07935.1424
13SZO002139.10334.9652
14SZO003139.05534.8158
15SZO007138.94734.9771
16SZO011138.60235.2128
17TKY007139.68635.7107
18TKY008139.39134.7852
19TKY009139.44134.6874
20TKY018139.81135.6551

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