RED-ACT: 06-17 M5.2 Japan Ibaraki-ken Earthquake
RED-ACT Report
Real-time Earthquake Damage Assessment using City-scale Time-history analysis
June 17, M5.2 Japan Ibaraki-ken Hokubu Earthquake
Research group of Xinzheng Lu at Tsinghua University (luxz@tsinghua.edu.cn)
First reported at 08:15, June 17, 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/software/Real-Time_Report.pdf
1. Introduction to the earthquake event
At 08:00 JST 17 2019 (Local Time, UTC +9), an M 5.2 (JMA) earthquake occurred in Japan Ibaraki-ken Hokubu. The epicenter was located at 140.6 36.5, with a depth of 80.0 km.
2. Recorded ground motions
35 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 234 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/software/Real-Time_Report.pdf
Table 1 Names and locations of the strong motion stations
No.Station NameLongitudeLatitude
1CHB007140.22735.7234
2FKS006140.75937.5031
3FKS008140.56737.4363
4FKS009140.63537.2778
5FKS013140.55637.09
6FKS014140.41736.8864
7FKS016140.19137.1228
8FKS017140.36937.2842
9FKS018140.36237.3961
10FKS019140.43737.603
11FKS024140.13237.3957
12FKS029139.3837.0159
13FKS031140.81337.3364
14IBR001140.35736.7761
15IBR002140.70736.7061
16IBR003140.64536.5915
17IBR004140.4136.5516
18IBR005140.23736.3851
19IBR006140.45436.3665
20IBR007140.59536.3523
21IBR008139.98336.3062
22IBR012140.27136.1954
23IBR013140.48936.1587
24IBR014140.19536.0729
25IBR017140.31935.9537
26IBR018140.63235.977
27TCG001140.08336.9417
28TCG003139.71536.8144
29TCG005139.92636.8061
30TCG006140.1336.7639
31TCG009139.71536.7258
32TCG013140.02336.4368
33TCG014140.17436.545
34TCG015139.71436.7489
35TCG016140.15636.5287
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