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Article

Spatiotemporal Analysis of Earthquake Distribution and Associated Losses in Chinese Mainland from 1949 to 2021

by
Tongyan Zheng
1,
Lei Li
2,3,4,
Chong Xu
2,3,* and
Yuandong Huang
2,3,5
1
China Earthquake Networks Center, Beijing 100045, China
2
National Institute of Natural Hazards, Ministry of Emergency Management of China, Beijing 100085, China
3
Key Laboratory of Compound and Chained Natural Hazards Dynamics, Ministry of Emergency Management of China, Beijing 100085, China
4
School of Engineering and Technology, China University of Geosciences (Beijing), Beijing 100083, China
5
School of Earth Sciences and Resources, China University of Geosciences (Beijing), Beijing 100083, China
*
Author to whom correspondence should be addressed.
Sustainability 2023, 15(11), 8646; https://doi.org/10.3390/su15118646
Submission received: 10 February 2023 / Revised: 21 May 2023 / Accepted: 23 May 2023 / Published: 26 May 2023
(This article belongs to the Special Issue Earthquake Engineering Technology and Its Application)
Browse Figures
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Abstract

:
A comprehensive earthquake hazard database is crucial for comprehending the characteristics of earthquake-related losses and establishing accurate loss prediction models. In this study, we compiled the earthquake events that have caused losses since 1949, and established and shared a database of earthquake hazard information for the Chinese mainland from 1949 to 2021. On this basis, we preliminarily analyzed the spatiotemporal distribution characteristics of 608 earthquake events and the associated losses. The results show the following: (1) The number of earthquakes is generally increasing, with an average of annual occurrence rising from three to twelve, and the rise in the economic losses is not significant. The number of earthquakes occurring in the summer is slightly higher than that in the other three seasons. (2) The average depths of earthquakes within the six blocks display a decreasing trend from west to east, with a majority (63.8%) of earthquakes occurring at depths ranging from 5 to 16 km. (3) Although the number of earthquakes in the east is lower than that in the west, earthquakes in the east are more likely to cause casualties when they have the same epicenter intensity. Southwest China is located in the Circum-Pacific seismic zone where earthquake hazards are highly frequent. The results can provide fundamental data for developing earthquake-related loss prediction models.

1. Introduction

Earthquakes are a natural geological phenomenon that can cause fatal destruction [1]. Due to the unpredictable suddenness and enormous energy released, earthquakes often result in a significant loss of people’s lives and property, causing devastating economic consequences [2,3]. According to statistics, more than one million earthquakes occur globally each year, equivalent to one earthquake every thirty seconds [4]. Regarding the earthquake magnitude, a total of 14,588 earthquakes with a magnitude of 4.0 or greater were recorded worldwide in only the year of 2015 (www.usgs.gov, accessed on 15 August 2022). Earthquakes can trigger not only immediate hazards such as fires, floods, and the diffusion of radioactive materials but also secondary disasters such as tsunamis, landslides, and collapses [5]. Although the topic of earthquake prediction has been proposed for a long time, its progress is slow. However, many studies have shown that the impact of earthquake hazards has a certain regularity [6,7,8,9,10]. For instance, Gutenberg et al. [11] evaluated the seismic activity of different plates of the Earth and discussed the topographic and geological characteristics of seismic zones.
The most important aspect after a destructive earthquake is the casualties [12,13]. In addition, statistics on the economic loss caused by the earthquake can help the government more directly understand the situation. How to accurately predict the casualties and economic losses caused by an earthquake and quickly provide post-earthquake emergency response management? Compiling a reliable database of historical earthquake hazard information is both the foundation and the key [14,15]. Based on the database, a series of forecasting models (empirical or analytical) can be established. It is mainly used in two parts: (1) estimating the number of casualties resulted from the earthquake [16,17,18] and (2) estimating the economic loss after the earthquake [19]. Samardjieva and Oike [20] approximated the number of casualties due to earthquakes using global seismic data and separated the data from the earthquake hazards in Japan. The data were further combined with a quantitative proportional model of the hazard. Samardjieva and Badal [12] analyzed the human losses after destructive earthquakes worldwide in the 20th century and proposed a quantitative model for the preliminary assessment of human casualties by relating the magnitude to the expected number of victims. Badal et al. [21] also considered the correlation of population density and conducted experiments in major cities in seismically active areas of Spain. Additionally, information on earthquake hazards from the Cambridge Earthquake Impacts Database (CEQID, www.ceqid.org) [22], Turkey [23], and Iran [15] was used to establish empirical models for estimating the number of fatalities. Xia et al. [24,25] proposed an earthquake lethality evaluation model based on building damage. Jaiswal and Wald [19] extended the USGS empirical lethality estimation method for immediate assessment of global earthquake response proposed by Jaiswal et al. [26] and rapidly estimated the economic loss after major earthquakes around the globe. Erdik et al. [27] systematically summarized the new methods and applications for estimating earthquake-related losses in real time over the past decades. Gerstenberger et al. [28] reviewed the research on earthquake hazard models in the past 50 years, and proposed future research directions.
China is located in the southeast of the Eurasian continent. Its eastern margin is affected by the Pacific Rim seismic zone, and the southwest and northwest regions are both located in the Eurasian seismic zone (Figure 1). The unique geographical location has made China an earthquake-prone country, and one of the countries that suffer the most severe losses from earthquake hazards [29,30]. On this basis, in this study, we established a database of earthquake hazard information for the Chinese mainland from 1949 to 2021. The database includes 608 earthquake events. We also analyzed their spatiotemporal distribution characteristics. In addition, earthquakes in neighboring countries have also caused some losses to China, and it should be noted that this kind of earthquakes are not included in the 608 seismic events. For example, the M6.8 earthquake in India on 18 September 2011 caused seven deaths and one hundred and thirty-six injuries in the Tibet Autonomous Region [31], and the M8.1 earthquake in Nepal on 25 April 2015 caused twenty-seven deaths and eight hundred and sixty injuries in the Tibet Autonomous Region [32]. A detailed database of earthquake hazard information is an important basis for understanding the characteristics of earthquake-hazard-related losses, establishing loss prediction models, and subsequently carrying out post-earthquake emergency rescues.

2. Data Collection and Methodology

The data used in this study come from two sources: (1) the China Earthquake Networks Center (https://www.ceic.ac.cn, accessed on 12 July 2022) that provided information on earthquake magnitude, date of occurrence, macroscopic epicenter, and depth; (2) provincial (autonomous regions and municipality) earthquake agencies that provided the assessment reports of earthquake-hazard-related losses, including both the casualties and economic loss. We also filled in some missing information in other ways [34].
During 1949–2021, earthquakes in the Chinese mainland totally caused 608 hazard events, 386 of which resulted in casualties (371,625 deaths and 1,304,936 injuries), while the remaining 222 earthquakes resulted in economic loss only. The most recent earthquake occurred on 16 September 2021 in Luxian County, Sichuan Province. This event caused three deaths and one hundred and fifty-seven injuries, with an economic loss of 364 million USD. The M7.8 earthquake that occurred in Tangshan, Hebei Province on 28 July 1976 caused the most tragic disaster. Statistically, 242,000 residents were killed, with nearly 170,000 serious injuries and more than 540,000 slight injuries. The economic loss reached nearly 73.45 billion USD. In addition, the M4.8 earthquake that occurred on 22 October 1965 in the south of Dalat Banner in Inner Mongolia caused minimal losses, with no casualties and a relatively low economic loss (14,000 USD).
We used ArcGIS 10.5 to edit the attributes of 608 seismic events, and established the earthquake hazard database for the Chinese mainland from 1949 to 2021. The attributes of the earthquakes in the database include date of occurrence, epicenter latitude and longitude, magnitude, intensity, focal depth, number of casualties, and economic loss. We fit the cumulative magnitude–frequency distribution [35] of 608 earthquakes using the Origin 2018 software, as shown in Figure 2. Using the classification criteria for earthquake events specified in the National Earthquake Emergency Plan, the cumulative magnitude–frequency distribution of earthquakes with general earthquake hazards and above (M ≥ 5) obeys an exponential distribution. Using statistical methods, we also quantified the characteristics of the spatiotemporal distribution [36] of earthquake events and the associated losses.

3. Results and Analysis

3.1. Characteristics of the Temporal Distribution of Earthquake Hazards and Associated Losses

3.1.1. The Pattern of a Decade

When analyzing the chronological pattern of earthquake events and the associated losses, we merged 1949 into the 1950s and similarly merged 2021 into the previous 10-year time period. In our analysis of economic loss, we converted the annual economic loss based on China’s GDP (Gross Domestic Product) data released by the National Bureau of Statistics of China (www.stats.gov.cn, accessed on 15 August 2022), using the economic loss in 2021 as a reference. From the 1950s to the last decade, the number of earthquakes showed a roughly increased trend (Figure 3a). The number of earthquakes has increased from an annual average of three to twelve (in the past 10 years), reaching the peak in the 1990s at an annual average of 12.8. The interdecadal average economic loss showed a jumping trend (Figure 3b), with the 2000s having an average annual economic loss of 33,510.4 million USD, followed by the 1970s with 15,478 million USD. The 1980s and 1990s had the fewest economic losses. The number of casualties is mainly controlled by major catastrophic earthquake events, and there is no obvious trend of an increase or decrease during the study period. For example, the two peaks in Figure 3c,d appeared in the 1970s and early 21st century, corresponding to the Tangshan earthquake in 1976 and the Wenchuan earthquake in 2008. A total of 82 earthquakes occurred in the decade 1970–1980, killing more than 260,000 people and injuring 767,000. The M7.8 earthquake that occurred in the densely populated Tangshan area in 1976 alone killed 242,000 people. In addition, with 110 earthquakes in the decade 2000–2010, the number is significantly higher. However, only about 70,000 people were killed and 390,000 were injured. In the 1980s and 1990s, casualties from earthquake events were minor. Although the economic loss caused by the earthquakes have reached an annual average of 4.21 billion USD in the past decade, the number of casualties has been effectively controlled. Details of the 23 typical earthquakes (M ≥ 7) that caused fatalities are listed in Table 1. Their geographical locations are shown in Figure 4. There is a clear concentration of developmental features in earthquake events with an M ≥ 6. Southwest China is a tectonically active earthquake-prone zone. When analyzing the chronological pattern of the number of deaths caused by the earthquakes, we considered the influence of magnitude. As shown in Figure 5, the magnitudes of the earthquakes that caused more than 1000 deaths were all above M6. The most devastating damage was caused by the 1976 Tangshan M7.8 earthquake, which killed 242,000 people and was the only earthquake to kill more than 100,000 people. There are also some unusual earthquakes in Figure 5, such as the 1969 Bohai M7.4 earthquake with a depth of 35 km. This earthquake was located in the Bohai Bay and killed only 10 people. In contrast, the Xiji M5.1 earthquake that occurred on the night of 3 December 1970, with a focal depth of 15 km, resulted in 117 fatalities because the local residents lived in earth kilns with extremely poor seismic resistance. The 1949 Kuche M7.3 earthquake and the 1955 Wuqia M7.0 earthquake both occurred within Xinjiang, which is among the least densely populated areas of the Chinese mainland. The fatalities caused by the two earthquakes were twelve and five, respectively, with a very low number of casualties. It can be seen that these unusual earthquakes are often related to the depth of the epicenter and the distribution of population.
In conclusion, the number of earthquakes shows a general upward trend, and the relationship between the economic loss and casualties and chronology is not obvious, which is mainly controlled by major catastrophic earthquake events.

3.1.2. Interannual Pattern

A total of 608 earthquake events causing losses occurred from 1949 to 2021, and Figure 6 illustrates the number of earthquake hazards for each year. There is a general upward trend in the number of earthquakes, with a significant decrease in the past two years. The average annual number of earthquakes from 1949 to 1960 is three. The number changes to seven and twelve for 1961–1990 and 1991–2019, respectively. However, there is no obvious stable trend in the annual number of earthquakes; for example, no earthquake event causing casualties occurred in 1968. There was a high incidence of earthquakes around 2000, in which 19 earthquake hazards occurred in 2003. After 2000, the number of earthquake events fluctuated around ten, with less than five in 2002 and 2007.
Overall, the number of earthquakes shows an upward trend, increasing from an annual average of three to twelve. However, there is no clear stable trend.

3.1.3. Seasonal Pattern

The 608 earthquakes were classified according to the number of deaths: ordinary earthquakes (causing less than 20 deaths), moderate earthquake hazards (causing 20–50 deaths), major earthquake hazards (causing 50–300 deaths), particularly major earthquake hazards (causing more than 300 deaths). Table 2 lists the seasonal distribution of each class of earthquake hazards, with six particularly major earthquakes occurring in winters and only two in autumns. Except for particularly major earthquakes, there is not much difference among the four seasons. As can be seen from Figure 7, no matter in which season the moderate or major earthquake hazards occur, Southwest China is always a high-incidence area. Detailed information of earthquake proportion in the Southwest is listed in Table 2. Table 3 lists the earthquake hazards and casualties for the four seasons, with the number of earthquakes occurring slightly higher in the summer than in the other three seasons. The Tangshan M7.8 earthquake on 28 July 1976 killed 242,000 people and injured more than 700,000; the Wenchuan M8 earthquake on 12 May 2008 killed 69,000 people and injured 375,000. These two earthquakes caused the highest number of casualties, which explains why the casualties in the spring and summer are the most serious. As mentioned above, the number of casualties is mainly influenced by major events. Figure 8 shows the number of fatalities caused by earthquakes with different magnitudes in each month. The nine earthquake events that led to more than 1000 fatalities are all distributed between January and August. Earthquake events with less than 100 fatalities are more evenly distributed in the four seasons.
In conclusion, the number of earthquakes during the studied time period is slightly higher in the summer than in the other three seasons. Specifically, the number of casualties is significantly higher in the summer, which is mainly influenced by major events.

3.2. Spatial Distribution Characteristics of Earthquake Hazards

3.2.1. Spatial Distribution of Earthquake Depths

The depth of the earthquake is the vertical distance from the epicenter to the ground, which is closely related to the tectonic zoning. Under the same conditions, the shallower the depth of the earthquake, the greater its destructive capacity. In this study, only 503 of the 608 earthquake events were recorded with accurate depths. The Chinese mainland is divided into six subregions according to the main tectonic block boundaries [37]. The spatial distribution of earthquake depths is shown in Figure 9. The earthquake depths in the Westfield fault block region are distributed in the range of 4–64 km, with an average depth of 19 km. The earthquake depths in the Tibetan fault block region are distributed in the range of 5–48 km, with an average depth of 17.4 km. Similarly, the earthquake depths of the Dian–Mian fault block region, South China fault block region, North China fault block region, Northeast Asia fault block region are 4–34, 4–48, 5–33, 5–30 km, with an average depth of 15.6, 13.2, 14.7, and 14.4 km, respectively. The earthquake depths between the blocks are distributed in the range of 5–50 km, with an average depth of 18 km. The M6.0 earthquake in Gashi, Xinjiang that occurred on 2 August 1998 is the deepest earthquake (64 km) on record, causing three injuries and an economic loss of 7.65 million USD. Among the 503 earthquake events, there are 321 (63.8%) events with an earthquake depth within 5–16 km. The detailed statistics of earthquake depths are shown in Figure 10. Finally, we analyzed the effect of the earthquake depth on the number of fatalities. As shown in Figure 11, all earthquakes causing more than 100 deaths have a focal depth of less than 25 km, mostly concentrated in the range of 10–20 km. When the focal depth exceeds 30 km, the number of fatalities is no larger than 10. Only two of the earthquake events with focal depths greater than 40 km resulted in fatalities: the Urumqi M6.6 earthquake in 1965 and the Atushi M5.7 earthquake in 1971. Notably, the 1976 M7.8 Tangshan earthquake was smaller in magnitude than the 2008 M8.0 Wenchuan earthquake, but it caused the largest number of fatalities. The epicenter of Tangshan earthquake is located in the downtown area of Tangshan City, with high population density, resulting in destructive housing damage and serious casualties. By contrast, the epicenter of the Wenchuan earthquake is located in a mountainous area, with a much smaller population density, and the regional secondary hazards are mainly landslides. Beichuan county, which has the highest concentration of casualties associated with the Wenchuan earthquake, is more than 100 km from the epicenter.
In conclusion, the average focal depths of the six plates in the Chinese mainland from west to east show a decreasing trend, and the focal depths of the earthquakes that caused more than 100 deaths are less than 25 km.

3.2.2. Spatial Distribution of Epicentral Intensity

Among the 608 earthquake events, 558 events show clear records of epicentral intensity. The M8.6 earthquake in Chayu, Tibet in 1950 is the only earthquake with an intensity of XII in the extreme seismic zone. The event caused 3300 deaths, 260 serious injuries, and an economic loss of 51,533.4 million USD. There are four earthquakes with an intensity of up to XI. Among them, the 1976 Tangshan earthquake and the 2008 Wenchuan earthquake caused more than 244,000 and 69,000 deaths, respectively, while the M8.0 earthquake in Nagqu, Tibet in 1951 and the M8.1 earthquake in Ruoqiang, Xinjiang in 2001 did not cause any fatalities. The epicenters of both earthquakes are in no-man’s land, and the distances to the nearest populated distribution sites are 74 and 400 km, respectively. Referring to Li et al. [36], the Chinese mainland was divided into two parts, East and West, using the “Hu Huanyong line” as the boundary. As shown in Figure 12, there are 40 earthquakes with an epicenter intensity greater than IX. Among them, only thirteen are distributed in the East. Eighty-seven earthquakes possess an epicenter intensity of VIII, and only twenty-seven of them are distributed in the East. Five of the twenty-seven events resulted in more than twenty deaths (including one with fifty-eight deaths), accounting for 18.5%. In contrast, among the sixty earthquake events that occurred in the West, only seven events resulted in more than twenty deaths, accounting for 11.7%. Additionally, Figure 12 shows that earthquakes with an epicentral intensity greater than VIII occur frequently in Sichuan and Yunnan Provinces, especially in Yunnan Province. Among the recorded earthquake events, the lowest intensity is V. Three of them also caused fatalities: the 1970 M4.8 earthquake in Qinglong, Guizhou, the 1986 M4.7 earthquake in Xiaxian, Shanxi, and the 1992 M4.6 earthquake in Sheyang, Jiangsu. In addition to analyzing the spatial distribution of earthquake intensity, the relationship between the intensity and the number of fatalities in combination with different magnitudes is displayed in Figure 13. Among the earthquake events that led to fatalities, those with intensities greater than X resulted in at least 50 deaths. Although the earthquakes with an intensity of V also caused fatalities, the death numbers are all smaller than three. Most of the earthquake events that caused more than 100 deaths have an intensity ≥ IX. The two exceptions are the M5.1 Xiji earthquake in 1970 and the M6.9 Daofu earthquake in 1981. In detail, the Daofu earthquake caused nearly 3000 Tibetan-style houses to collapse, killing 126 people. The number of fatalities is controlled by multiple factors, and in terms of intensity alone, the number of fatalities shows a roughly increasing trend as the intensity increases. Some earthquakes in Figure 13 do not satisfy this trend, including the 1952 Naqu earthquake, the 1954 Alashan earthquake, and the 1955 Kangding earthquake. These events are all characterized by an intensity of X, resulting in less than 100 fatalities. The 1950 Chayu earthquake killed only 3300 people, although it reached an intensity of XII. After analyzing the historical data, the seismic macro-damage and intensity distribution of the above events were in the sparsely populated areas.
Overall, in terms of intensity alone, the number of fatalities increases with the increasing intensity. The proportion of deaths caused by the earthquakes is higher in the East (bounded by the “Hu Huanyong line”) due to the high regional population density.

4. Discussion

Based on the earthquake hazard data from the China Earthquake Networks Center and the provincial (autonomous region and municipality) earthquake agencies, we established a database of earthquake hazard information for the Chinese mainland from 1949 to 2021, and preliminarily analyzed the spatiotemporal distribution characteristics of 608 earthquake events and the associated losses. In this study, we only used basic statistical analysis methods, which have certain limitations, and this will be a direction to be addressed in future studies. The number of earthquakes is basically on the rise, which is related to the continuous improvement of statistical tools. No obvious trend of an increase or decrease in the number of casualties was observed during the study period, which was mainly associated with particularly major events. Although the economic loss caused by the earthquakes has reached an annual average of 4.21 billion USD in the past 10 years, the number of casualties has been effectively controlled. As the economy grows, people begin to invest more in life security. Coupled with the increasing attention to safety by governments, earthquake hazards are gradually changing from a threat to personal safety to a threat to property [36]. Different from Lin et al.’s [38] study that investigated the seasonal distribution characteristics of fatal landslides, the season when earthquakes occur and the influencing factors of losses are not obvious. However, no matter in which season the moderate or major earthquake hazards occur, the Southwest China is always a high-incidence area. The reason is that the western part of the Sichuan–Yunnan block is located at the junction zone of the Indian Ocean plate, Eurasian plate, and Pacific plate. Such a region belongs to the Pacific Rim seismic zone, which is an earthquake-prone area.
The average earthquake depths of the six blocks in the Chinese mainland show a decreasing trend from west to east, which is consistent with Shao et al.’s data [39]. In their study, the Chinese mainland was divided into two subregions (using 105°E as the boundary), eastern and western regions, with the depth of earthquakes in the latter being slightly greater than that in the former. It is also believed that when the earthquake magnitudes are comparable, the damage in the epicenter region will be heavier in the east and lighter in the west. Casualties caused by earthquake hazards are significantly influenced by the population density. Taking the population division line, the “Hu Huanyong line”, as the boundary, the number of earthquakes in the East is much lower than that in the West, but under the same epicenter intensity, earthquakes are more likely to cause casualties in the East because the population density is much higher there than that in the West. Chen et al. [40] used indicators such as seismic intensity and population density to present a simplified methodology to assess earthquake risk, which provided effective, if rough, earthquake damage information for initial response and/or risk management planning in the Chinese mainland. This, of course, is also related to aspects such as awareness of earthquake hazard prevention and the earthquake resistance of buildings. However, there are studies with different claims, such as the anti-lethal level proposed by Xia et al. [14], where the average anti-lethal level was higher in the east of China than in the west. Coseismic landslides are also a major cause of a large number of casualties [41,42]. Further analyses need to be completed with the support of more data, which is also the goal of our future study.
The establishment and preliminary analysis of the earthquake hazard information database are the basis for understanding the characteristics of earthquake-related losses and establishing a series of casualty prediction models (e.g., loss prediction models based on factors such as the location of the earthquake occurrence, magnitude, and focal depth). The construction of a population-loss evaluation model will allow for the prediction of population casualties in future earthquake scenarios. The database of earthquake hazard information in this study contains 608 earthquakes, and our data are richer in both the involved years and the number of earthquake events, relative to the studies by Chen et al. [43] and Wu et al. [18]. There are other contributing factors that deserve further studies [44]. Rapid assessment of earthquake casualties can provide a scientific basis and data reference for post-earthquake emergency rescue. However, there are some limitations in this study: the casualties caused by the earthquakes vary with the moment of the earthquake [44]. During the construction of the earthquake hazard information database, specific moments of earthquake occurrence were not included. In addition, the influencing factors of earthquake casualties [2] and the specific geographical location of casualties were not discussed. Hazard analysis of major earthquake events and prediction of earthquake damage and casualties will be the focus of future work.

5. Conclusions

In this study, we collected 608 earthquake events causing losses in the Chinese mainland during the period 1949–2021. Among them, 222 earthquakes caused only economic damage, while the remaining 386 events resulted in more than 370,000 deaths and 1.3 million injuries. We used the ArcGIS 10.5 software to edit the attributes of 608 events and established a database of earthquake hazard information. We further analyzed the spatiotemporal distribution of earthquake hazards and the associated losses. The conclusions of this study are as follows:
(1) From the 1950s to the last decade, the number of earthquakes roughly shows an increasing trend, with the number of earthquakes increasing from an annual average of three to twelve, but there is no clear stable trend. The number of earthquakes during the studied time period is slightly higher in the summer than in the other three seasons. The number of casualties is significantly higher in the summer than in the other three seasons, which is mainly influenced by major events. No matter in which season the moderate or major earthquake hazards occur, Southwest China is always a high-incidence area.
(2) The average earthquake depths of the six blocks from west to east show a decreasing trend. The largest focal depth was found in the Westfield fault block region. The average focal depths of the three blocks in South China, North China, and Northeast Asia are relatively small. In the statistical earthquake events, the focal depth distribution in the range of 5–16 km accounts for a high proportion (63.8%). The focal depths of the earthquakes that caused more than 100 deaths are all within 25 km.
(3) In terms of epicenter intensity alone, the number of deaths caused by the earthquakes shows a basically increasing trend with the increasing intensity. Affected by the population density, the proportion of deaths caused by the earthquakes is higher in the East (bounded by the “Hu Huanyong line”).

Author Contributions

C.X. and T.Z. proposed the research concept and provided basic data. L.L. designed the framework and wrote the manuscript. Y.H. provided basic data. All authors have read and agreed to the published version of the manuscript.

Funding

This study was supported by the National Institute of Natural Hazards, Ministry of Emergency Management of China (ZDJ2021-12).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The earthquake hazard information database (in shp. format) used in this study are freely available at this link: https://zenodo.org/record/7800432.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Shadmaan, S.; Islam, A.I. Estimation of earthquake vulnerability by using analytical hierarchy process. Nat. Hazards Res. 2021, 1, 153–160. [Google Scholar] [CrossRef]
  2. Shen, Z.; Jackson, D.; Kagan, Y. Implications of geodetic strain rate for future earthquakes in southern California. Seismol. Res. Lett. 2007, 78, 116–120. [Google Scholar] [CrossRef]
  3. Wang, W.; Chen, H.; Jiang, X.; Ma, L.; Xu, Y.; Qu, M. Lessons from the casualties caused by the Changning M 6.0 earthquake in China. Nat. Hazards Res. 2021, 1, 81–87. [Google Scholar] [CrossRef]
  4. Dong, L.; Shan, J. A comprehensive review of earthquake-induced building damage detection with remote sensing techniques. ISPRS J. Photogramm. Remote Sens. 2013, 84, 85–99. [Google Scholar] [CrossRef]
  5. Ren, J.; Zhang, Z.; Gai, H.; Kang, W. Typical Riedel shear structures of the coseismic surface rupture zone produced by the 2021 Mw 7.3 Maduo earthquake, Qinghai, China, and the implications for seismic hazards in the block interior. Nat. Hazards Res. 2021, 1, 145–152. [Google Scholar] [CrossRef]
  6. Kanamori, H. The energy release in great earthquakes. J. Geophys. Res. 1977, 82, 2981–2987. [Google Scholar] [CrossRef]
  7. Farolfi, G.; Keir, D.; Corti, G.; Casagli, N. Spatial forecasting of seismicity provided from earth observation by space satellite technology. Sci. Rep. 2020, 10, 9696. [Google Scholar] [CrossRef]
  8. Nakamura, M.; Kinjo, A. Activated seismicity by strain rate change in the Yaeyama region, south Ryukyu. Earth Planets Space 2018, 70, 154. [Google Scholar] [CrossRef]
  9. Zeng, Y.; Petersen, M.; Shen, Z. Earthquake potential in California-Nevada implied by correlation of strain rate and seismicity. Geophys. Res. Lett. 2018, 45, 1778–1784. [Google Scholar] [CrossRef]
  10. Riguzzi, F.; Crespi, M.; Devoti, R.; Doglioni, C.; Pietrantonio, G. Geodetic strain rate and earthquake size: New clues for seismic hazard studies. Phys. Earth Planet. Inter. 2012, 206, 67–75. [Google Scholar] [CrossRef]
  11. Gutenberg, G.; Richter, C.F. Seismicity of the earth and associated phenomena, Howard Tatel. J. Geophys. Res. 1950, 55, 97. [Google Scholar]
  12. Samardjieva, E.; Badal, J. Estimation of the expected number of casualties caused by strong earthquakes. Bull. Seismol. Soc. Am. 2002, 92, 2310–2322. [Google Scholar] [CrossRef]
  13. Nie, G.; An, J.; Deng, Y. Advances in earthquake emergency disaster service. Seismol. Geol. 2012, 34, 782–791. (In Chinese) [Google Scholar]
  14. Xia, C.; Nie, G.; Li, H.; Fan, X.; Qi, W. A composite database of casualty-inducing earthquakes in mainland China. Nat. Hazards 2023, 116, 3321–3351. [Google Scholar] [CrossRef]
  15. Firuzi, E.; Amini Hosseini, K.; Ansari, A.; Izadkhah, Y.O.; Rashidabadi, M.; Hosseini, M. An empirical model for fatality estimation of earthquakes in Iran. Nat. Hazards 2020, 103, 231–250. [Google Scholar] [CrossRef]
  16. Oike, K.; Hori, T. History of earthquakes and seismic disasters in east Asia. Science 1998, 68, 409–415. [Google Scholar]
  17. Koshimura, S.; Katada, T.; Mofjeld, H.O.; Kawata, Y. A method for estimating casualties due to the tsunami inundation flow. Nat. Hazards 2006, 39, 265–274. [Google Scholar] [CrossRef]
  18. Wu, X.; Gu, J.; Wu, H. A modified exponential model for reported casualties during earthquakes. Acta Seism. Sin 2009, 31, 457–463. [Google Scholar]
  19. Jaiswal, K.; Wald, D.J. Estimating economic losses from earthquakes using an empirical approach. Earthq. Spectra 2013, 29, 309–324. [Google Scholar] [CrossRef]
  20. Samardjieva, E.; Oike, K. Modelling the number of casualties from earthquakes. J. Nat. Disaster Sci. 1992, 14, 17–28. [Google Scholar]
  21. Badal, J.; Vázquez-Prada, M.; González, Á. Preliminary quantitative assessment of earthquake casualties and damages. Nat. Hazards 2005, 34, 353–374. [Google Scholar] [CrossRef]
  22. So, E.; Spence, R. Estimating shaking-induced casualties and building damage for global earthquake events: A proposed modelling approach. Bull. Earthq. Eng. 2013, 11, 347–363. [Google Scholar] [CrossRef]
  23. Turkan, S.; Özel, G. Modeling destructive earthquake casualties based on a comparative study for Turkey. Nat. Hazards 2014, 72, 1093–1110. [Google Scholar] [CrossRef]
  24. Xia, C.; Nie, G.; Fan, X.; Zhou, J.; Li, H.; Pang, X. Research on the rapid assessment of earthquake casualties based on the anti-lethal levels of buildings. Geomat. Nat. Hazards Risk 2020, 11, 377–398. [Google Scholar] [CrossRef]
  25. Xia, C.; Nie, G.; Fan, X.; Zhou, J.; Li, H.; Zhou, J.; Zeng, X. A new model for the quantitative assessment of earthquake casualties based on the correction of anti-lethal level. Nat. Hazards 2022, 110, 1199–1226. [Google Scholar]
  26. Jaiswal, K.; Wald, D.J.; Hearne, M. Estimating Casualties for Large Earthquakes Worldwide Using an Empirical Approach; USGS: Columbus, OH, USA, 2009. [Google Scholar]
  27. Erdik, M.; Şeşetyan, K.; Demircioğlu, M.; Hancılar, U.; Zülfikar, C. Rapid earthquake loss assessment after damaging earthquakes. Soil Dyn. Earthq. Eng. 2011, 31, 247–266. [Google Scholar] [CrossRef]
  28. Gerstenberger, M.C.; Marzocchi, W.; Allen, T.; Pagani, M.; Adams, J.; Danciu, L.; Field, E.H.; Fujiwara, H.; Luco, N.; Ma, K.-F.; et al. Probabilistic seismic hazard analysis at Regional and National Scales: State of the art and challenges. Rev. Geophys. 2020, 58, e2019RG000653. [Google Scholar] [CrossRef]
  29. Nie, G.; Gao, J.; Ma, Z.; Gao, Q.; Su, G. On the risk of earthquake disaster in China in the coming 10~15 years. J. Nat. Disasters 2002, 11, 68–73. (In Chinese) [Google Scholar]
  30. Wei, Y. Earthquake Safety Estimation Study for the Urban Rail Transportation Engineering Field. Master’s Thesis, Central South University, Changsha, China, 2009. (In Chinese). [Google Scholar]
  31. Zheng, T.; Zheng, Y. Review of earthquake damage losses in mainland China in 2011. J. Nat. Disasters 2012, 21, 88–97. (In Chinese) [Google Scholar]
  32. Chen, T.; Zheng, T. Review of earthquake damage losses in mainland China in 2015. J. Catastrophol. 2016, 31, 133–137. (In Chinese) [Google Scholar]
  33. Zhao, B.; Huang, Y.; Zhang, C.; Wang, W.; Tan, K.; Du, R. Crustal deformation on the Chinese mainland during 1998–2014 based on GPS data. Geod. Geodyn. 2015, 6, 7–15. [Google Scholar] [CrossRef]
  34. Huang, X.; Jin, H. An earthquake casualty prediction model based on modified partial Gaussian curve. Nat. Hazards 2018, 94, 999–1021. [Google Scholar] [CrossRef]
  35. Lindenfeld, M.; Rümpker, G.; Batte, A.; Schumann, A. Seismicity at the Rwenzori Mountains, East African Rift: Earthquake distribution, magnitudes and source mechanisms. Solid Earth Discuss. 2012, 4, 565–598. [Google Scholar]
  36. Li, W.; Chen, W.; Zhou, Z.; Gao, N.; Chen, J. Analysis of temporal-spatial distribution of life losses caused by earthquake hazards in Chinese mainland. J. Catastrophol. 2019, 34, 222–228. (In Chinese) [Google Scholar]
  37. Li, W.; Chen, W.; Zhou, Z.; Gao, N.; Sun, Y. Assessing the applicability of life vulnerability models for earthquake disasters in typical regions of China. J. Beijing Norm. Univ. 2019, 55, 284–290. (In Chinese) [Google Scholar]
  38. Lin, Q.; Wang, Y. Spatial and temporal analysis of a fatal landslide inventory in China from 1950 to 2016. Landslides 2018, 15, 2357–2372. [Google Scholar] [CrossRef]
  39. Shao, D.; Sun, Z.; Tian, Q.; Zhang, W. Statistical analysis of historical earthquake intensity in Chinese mainland. Seismol. Geomagn. Obs. 2018, 39, 135–140. (In Chinese) [Google Scholar]
  40. Chen, Q.; Mi, H.; Huang, J. A simplified approach to earthquake risk in mainland China. Pure Appl. Geophys. 2005, 162, 1255–1269. [Google Scholar] [CrossRef]
  41. Cui, S.; Wu, H.; Pei, X.; Yang, Q.; Huang, R.; Guo, B. Characterizing the spatial distribution, frequency, geomorphological and geological controls on landslides triggered by the 1933 Mw 7.3 Diexi Earthquake, Sichuan, China. Geomorphology 2022, 403, 108177. [Google Scholar] [CrossRef]
  42. Xiao, Z.; Xu, C.; Huang, Y.; He, X.; Shao, X.; Chen, Z.; Xie, C.; Li, T.; Xu, X. Analysis of spatial distribution of landslides triggered by the Ms 6.8 Luding earthquake in China on September 5, 2022. Geoenvironmental Disasters 2023, 10, 3. [Google Scholar] [CrossRef]
  43. Shapira, S.; Aharonson-Daniel, L.; Shohet, I.M.; Peek-Asa, C.; Bar-Dayan, Y. Integrating epidemiological and engineering approaches in the assessment of human casualties in earthquakes. Nat. Hazards 2015, 78, 1447–1462. [Google Scholar] [CrossRef]
  44. Nan, Y.; Liu, K.; Gao, B.; Zhang, X.; Li, Y. Discussion on the grade scales of natural disasters by the losses in Wenchuan earthquake. J. Catastrophol. 2021, 36, 42–47. (In Chinese) [Google Scholar]
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Figure 1. The geographical location of China. White arrows indicate plate forces; yellow arrows indicate regional GPS velocity (time period: 2009–2014) [33].
Figure 1. The geographical location of China. White arrows indicate plate forces; yellow arrows indicate regional GPS velocity (time period: 2009–2014) [33].
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Figure 2. Relationship between earthquake magnitude and frequency. Value lg(N) refers to the logarithm of N. N denotes the cumulative number of earthquakes that resulted in human casualties or economic loss.
Figure 2. Relationship between earthquake magnitude and frequency. Value lg(N) refers to the logarithm of N. N denotes the cumulative number of earthquakes that resulted in human casualties or economic loss.
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Figure 3. Chronological pattern of earthquake events and statistics of the losses caused: (a) number of earthquakes in a decade; (b) economic loss in a decade; (c) number of fatalities per year (black) and number of the M ≥ 7 earthquakes in a decade (red); (d) number of the injured per year (black) and number of the M ≥ 6 earthquakes in a decade (red).
Figure 3. Chronological pattern of earthquake events and statistics of the losses caused: (a) number of earthquakes in a decade; (b) economic loss in a decade; (c) number of fatalities per year (black) and number of the M ≥ 7 earthquakes in a decade (red); (d) number of the injured per year (black) and number of the M ≥ 6 earthquakes in a decade (red).
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Figure 4. Spatial distribution of seismic events (M ≥ 6) that caused fatalities. Numbered in red: locations of 23 typical earthquakes (M ≥ 7); unnumbered: M6–7 earthquakes.
Figure 4. Spatial distribution of seismic events (M ≥ 6) that caused fatalities. Numbered in red: locations of 23 typical earthquakes (M ≥ 7); unnumbered: M6–7 earthquakes.
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Figure 5. Interannual distribution characteristics of deaths caused by earthquakes with different magnitudes. The number is listed in Table 1.
Figure 5. Interannual distribution characteristics of deaths caused by earthquakes with different magnitudes. The number is listed in Table 1.
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Figure 6. Number of interannual earthquakes.
Figure 6. Number of interannual earthquakes.
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Figure 7. Seasonal distribution of earthquakes. Geographical zones: N.W.—Northwest, S.W.—Southwest, S.C.—South China, C.C.—Central China, N.C.—North China, E.C.—East China, N.E.—northeast. The subfigure in the lower right corner represents South China Sea.
Figure 7. Seasonal distribution of earthquakes. Geographical zones: N.W.—Northwest, S.W.—Southwest, S.C.—South China, C.C.—Central China, N.C.—North China, E.C.—East China, N.E.—northeast. The subfigure in the lower right corner represents South China Sea.
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Figure 8. Inter-monthly distribution characteristics of the number of deaths caused by earthquakes with different magnitudes. The number is listed in Table 1.
Figure 8. Inter-monthly distribution characteristics of the number of deaths caused by earthquakes with different magnitudes. The number is listed in Table 1.
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Figure 9. Spatial distribution of earthquake depths. The block information is referenced to Zhang et al. [37]. W.F.B.R.—Westfield fault block region (F.B.R.—fault block region), T.—Tibetan, D.—Dian–Mian, S.—South China, N.—North China, N.A.—Northeast Asia. Faults: 1—Lijia, 2—Yushu–Xianshui river zone, 3—East Kunlun, 4—Alkin, 5—Nantian mountain, 6—Beitian mountain, 7—Anning–Zemu river zone, 8—Longmen mountain, 9—Tango, 10—Shanxi.
Figure 9. Spatial distribution of earthquake depths. The block information is referenced to Zhang et al. [37]. W.F.B.R.—Westfield fault block region (F.B.R.—fault block region), T.—Tibetan, D.—Dian–Mian, S.—South China, N.—North China, N.A.—Northeast Asia. Faults: 1—Lijia, 2—Yushu–Xianshui river zone, 3—East Kunlun, 4—Alkin, 5—Nantian mountain, 6—Beitian mountain, 7—Anning–Zemu river zone, 8—Longmen mountain, 9—Tango, 10—Shanxi.
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Figure 10. Depths of earthquake. I-VI denote six blocks, see Figure 6, *VII denotes between the blocks.
Figure 10. Depths of earthquake. I-VI denote six blocks, see Figure 6, *VII denotes between the blocks.
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Figure 11. Focal depth distribution characteristics of the number of deaths caused by earthquakes with different magnitudes. The number is listed in Table 1.
Figure 11. Focal depth distribution characteristics of the number of deaths caused by earthquakes with different magnitudes. The number is listed in Table 1.
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Figure 12. Spatial distribution of epicentral intensity. “Hu Huanyong line” [36]—a population division line separating China into two parts, East and West.
Figure 12. Spatial distribution of epicentral intensity. “Hu Huanyong line” [36]—a population division line separating China into two parts, East and West.
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Figure 13. Intensity distribution of the number of deaths caused by earthquakes with different magnitudes. The number is listed in Table 1.
Figure 13. Intensity distribution of the number of deaths caused by earthquakes with different magnitudes. The number is listed in Table 1.
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Table
Table 1. Twenty-three typical earthquakes (M ≥ 7) that caused fatalities.
Table 1. Twenty-three typical earthquakes (M ≥ 7) that caused fatalities.
No.DateEpicenterMagnitudeIntensityEconomic Losses (Million USD)FatalitiesInjured
115 August 1950Chayu8.6XII51,533.43300260
212 May 2008Wenchuan8XI317,020.769,227375,783
35 January 1970Tonghai7.8X+2985.415,62126,783
428 July 1976Tangshan7.8XI73,447.6242,000708,602
56 February 1973Luhuo7.6X16,618.421992743
618 August 1952Naqu7.5X12,883.4540
714 April 1955Kangding7.5X6283.994260
818 July 1969Bohai7.4IX593.910353
929 May 1976Longling7.4IX1062.8982442
106 November 1988Lancang7.4IX6676.47487751
1124 February 1949Kuche7.3IX-1220
124 February 1975Haiyu7.3IX+60,513.3132816,980
1311 February 1954Alashan7.2X12,357.050329
1422 March 1966Ningjin7.2X12,567.7806438,451
1516 August 1976Songfan7.2IX-41756
1611 May 1974Yanjin7.1IX730.815411600
1723 August 1985Wuqia7.1IX335.467256
1814 April 2010Yushu7.1IX7023.5269811,000
1915 April 1955Wuqia7IX6283.9513
2026 April 1990Gonghe7IX615.01192049
213 February 1996Yulong7IX2878.930917,057
2220 April 2013Lushan7IX16,053.719613,019
238 August 2017Jiuzhaigou7IX1483.829543
Table
Table 2. Seasonal distribution of earthquake hazards.
Table 2. Seasonal distribution of earthquake hazards.
Particularly MajorMajorModerate* Ordinary
Spring445130
Summer337156
Autumn243142
Winter623134
Total151318562
* Ordinary earthquake events include earthquakes that do not cause casualties.
Table
Table 3. Earthquake hazards and casualties in four seasons.
Table 3. Earthquake hazards and casualties in four seasons.
Number of Earthquakes Causing CasualtiesFatalities
Spring9082,283
Summer110246,470
Autumn912144
Winter9520,998
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Zheng, T.; Li, L.; Xu, C.; Huang, Y. Spatiotemporal Analysis of Earthquake Distribution and Associated Losses in Chinese Mainland from 1949 to 2021. Sustainability 2023, 15, 8646. https://doi.org/10.3390/su15118646

AMA Style

Zheng T, Li L, Xu C, Huang Y. Spatiotemporal Analysis of Earthquake Distribution and Associated Losses in Chinese Mainland from 1949 to 2021. Sustainability. 2023; 15(11):8646. https://doi.org/10.3390/su15118646

Chicago/Turabian Style

Zheng, Tongyan, Lei Li, Chong Xu, and Yuandong Huang. 2023. "Spatiotemporal Analysis of Earthquake Distribution and Associated Losses in Chinese Mainland from 1949 to 2021" Sustainability 15, no. 11: 8646. https://doi.org/10.3390/su15118646

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