Peijun SHI1,2,3, Jing’ai WANG1,3,4, Wei XU2,3, Jiabing SHUAI1,2, Lili LU1,2, Feng KONG1,2, Qinqing SHI5 1State Key Laboratory of Earth Surface Processes and Resource Ecology of Beijing Normal University, China; 2Key Laboratory of Environmental Change and Natural Disaster of Ministry of Education, Beijing Normal University, China; 3Academy of Disaster Reduction and Emergency Management of Ministry of Civil Affairs and Ministry of Education, Beijing Normal University, China; 4School of Geography, Beijing Normal University, China; 5The University of Maryland, USA;

1. 4th International Disaster and Risk Conference IDRC Davos 2012
"Integrative Risk Management in a Changing World - Pathways to a Resilient Society"
26-30 August 2012
Davos, Switzerland
Formation mechanism, processes and risk assessment
system of disaster group and disaster chain
Peijun Shi
State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal University;
Key Laboratory of Environmental Change and Natural Disaster, Ministry of Education of China;
Academy of Disaster Reduction and Emergency Management, Ministry of Civil Affairs & Ministry of
Education, P.R.China
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2. Contents
1 Background
2 Disaster Group (DG) and Disaster Chain (DC)
3 DG and DC Risk Assessment System
4 The Case Study of DG and DC
5 Conclusions
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3. 1 Natural disasters, especially the large-scale disasters (LSD) have become the biggest obstacle to the

Background
achievement of the Millennium Development and Sustainable Development. (UNDP,2004)
 The relationship between LSD and disaster chain, disaster groups: disaster chain and disaster groups
may expand the scope of disaster areas or increase the intensity of hazard, then aggravate the disaster.
2004 Indian Ocean earthquake-tsunami LSD 2008 Southern China snow-ice strom LSD
3
2008 Wenchuan earthquake-landslide LSD 2011 Japan earthquake-tsunami LSD

4. Contents
1 Background
 2 Disaster Group (DG) and Disaster Chain (DC)
 3 DG and DC Risk Assessment System
 4 The Case Study of DG and DC
 5 Conclusions
4

5. 2 Disaster Group and Disaster Chain
 Definition of Disaster Group （ Muti-Hazards): the
phenomenon that various hazards happen during the
same period triggered by a specific factor of the Earth
system, or several hazards cluster in the same place
controlled by a factor of the Earth surface.
 Definition of Disaster Chain: the phenomenon that
the occurrence of a hazard causes series of secondary
disasters.
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6. 2 Disaster Group and Disaster Chain
 Formation of Disaster Group:
Fig.1 The general mode of disaster group (Mode of setting off a chain of events)
E represents the natural dynamic processes of the Earth system, H1,..Hm represent original hazards.
 Formation of Disaster Chain:
Fig.2 Parallel disasters chain (the mode that Fig. 3 Serial disaster chain (a "domino effect"
a tossed stone raises a thousand ripples) mode)
E represents the natural dynamic processes of the H represents the hazard, d1 represents the original
Earth system, H1,..Hm represent original hazards, disaster, dn represents secondary disasters.
d1, dn, dm1, dmn represent secondary disasters.
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7. 2 Disaster Group and Disaster Chain
 Difference between Disaster Group and Disaster Chain:
Disaster Group Disaster Chain
Concurrent and frequent processes Disaster chain is a chain process
of disaster groups rely on the geo- that a particular hazard causes
spatial location (ie, latitude and another hazard or multiple
longitude) and evolution stage, with hazards, mainly depending on the
little association with geographical specific physical and human
environment. geography environment.
Mainly depend on the linkage Closely related to the risk
between the natural elements of defensive capability of human
Earth system beings.
Muti-hazarts meeting to together can Disaster chains can cause large-scale
cause large-scale disaster disaster
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8. Contents
1 Background
 2 Disaster Group (DG) and Disaster Chain (DC)
 3 DG and DC Risk Assessment System
 4 The Case Study of DG and DC
 5 Conclusions
8

9. 3 DG and DC Risk Assessment System
 Disaster Group Risk Assessment System:
Disaster group risk assessment is basically consistent with multi-hazard
risk assessment. Disaster group risk assessment is consisted of three parts,
including assessment of the hazard-formative environment
stability(sensing), multi-hazards assessment, vulnerability assessment of
disaster-affected bodies.
 Disaster Chain Risk Assessment System:
Although the literature of the disaster chain risk assessment is relatively few,
researchers are trying to find a variety of quantitative methods to assess the
disasters chains risk. Typical methods include case index system method,
the hazard trees model, the domino effect model, the Cascading effect model
etc.
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10. 3 DG and DC Risk Assessment System
Framework of DG and DC Risk Assessment
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11. Contents
1 Background
 2 Disaster Group (DG) and Disaster Chain (DC)
 3 DG and DC Risk Assessment System
 4 The Case Study of DG and DC
 5 Conclusions
11

12. 4 The Case Study of DC
Case study of Disaster Chain-Wenchuan Earthquake
 14:28 pm on May 12 of 2008, a major earthquake
measuring 8 Richter scale jolted Wenchuan County of
Southwest China’s Sichuan province.
 The most serious earthquake of China since 1949:
 high intensity
 large disaster-affected area
 serious frequent aftershocks and secondary disasters
 the enormous difficulties in emergency response
 the most severe damages and losses
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13. Power—Communication
Freezing Rain & Snowstorm Disaster, Southern of China, 2008

15. 山体崩塌
Mountain Collapse
从山顶至山谷 200—300 米
唐家山堰塞湖坝顶一角

16. Map of Seismic Intensity Zoning
VII
VIII
Epicenter
The most inner intensity is: IX(9), X(10) grade and its above
依据中国地震局现场调查数据、航卫片判读、强震记录、余震分布、震源破裂过程、地震地面运动拟合
数据、震源机制、地表破裂形迹等综合编制。国家汶川地震专家委员会地震烈度等震线评估组。 08 －
05 － 27 。
Inner material by the State Seismological Bureau of China

17. 4 The Case Study of DC
Heavy Rain
Rock Collapse Landslides Debris Flow Barrier lakes
Earthquake
Wenchuan Earthquake Disaster Chain
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18. 4 The Case Study of DC
DI=∑(fk* DIk)
Disaster Index:
DIk is the normalized indicator value ： DIk = [DIk –min(DIk)]/ [max(DIk)-
min(DIk)] ； fk is the weight for each indicator
Indicators and Weights
Indicator (DIk ） Weight （ f
k）
Average magnitude of earthquake 0.30
Indices of geological disaster Impacted Residents 0.10
deaths and missing Number of deaths and missing people 0.15
people percentage of deaths and missing people 0.15
collapsed houses Number of collapsed houses 0.10
Number of collapsed houses per 10,000 0.10
persons
Percentage of people relocated 0.10

19. 4 The Case Study of DC
The Estimation of Losses
Provinces Losses (billion RMB) Percentage(%)
Sichuan 771.8 90.5
Gansu 50.5 5. 9
Shaan’xi 22.8 2.7
Chongqing 5.4 0.6
Yunan 1.7 0.2
Ningxia 0.8 0.1
Total 853.0 100.0

20. 4 The Case Study of DG
Case study of Disaster Group-Snow and ice
storm in Southern China
 From mid-January to early February, 2008, most parts
of China, especially Southern China experienced this
sever snow and ice storms disaster.
 The most serious snow and ice storms disaster in
Southern Chinasince 1949:
 Affected wide-range area
 Lasted for long period
 Extreme lower temperature
 Affluence precipitation
 Thick snow frozen
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21. Power—Communication
Freezing Rain & Snowstorm Disaster, Southern of China, 2008

22. 4 The Case Study of DG
Snow and Ice Storm Disaster Groups in Southern China
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23. 4 The Case Study of DG
The four layers of ice accumulated during the four sub-events from January
10 to February 6, 2008 in Hunan Province
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24. 4 The Case Study of DG
Direct Economic Loss: 159.48 billion RMB
Indirect Economic Loss Estimation Model:
Loss=Σxiqi
Where, Xi is the total production amount of ith industrial sector; qi is the
production amount of ith industrial sector after disaster with its normal
production amount.
Indirect economic loss Losses (billion RMB)
caused by
Failure of Electricity 6.25
Traffic Disruption 3.95
The Estimation of Indirect Economic Losses in Hunan Province
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25. Contents
1 Background
 2 Disaster Group (DG) and Disaster Chain (DC)
 3 DG and DC Risk Assessment System
 4 The Case Study of DG and DC
 5 Conclusions
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26. 5 Conclusions
 Disaster group(Muti-Hazarts) and disaster chain are distinguished.
 Based on disaster system theory, formation of the disaster group mainly
relates to physical hazard-formative environments, and the formation of the
disaster chain is closely related to physical hazard-formative environments
and exposures.
 Disaster chain risk assessment and multi--hazarts risk assessment have a
fundamentally difference. For risk assessment of disaster group (multi-
hazarts), except for consideration of probability of each hazard, possiability
of multiple hazards meet together shall be assessed of certain space-time
condition. For risk assessment of disaster chain, in addition to the probability
of first hazard, probability that lead to secondary hazard shall be assessed
under certain space-time condition.
 Based on the understanding of disaster group and disaster chain formation
mechanism and process, we conducted two cases study and the results were
presented.
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27. Thank you ！
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