**2. The earthquake induced landslide**

A strong earthquake can induce a large amount of landslides and cause very serious property damage and human casualties. This phenomenon was recorded in ancient China dated back to 1789 BCE, and in ancient Greece 2373 years ago (Keefer, 2002). There have been many reports about the very serious damages caused by the earthquake induced landslides for the last few decades. For example, 9,272 landslides induced by the 1999 Chi-Chi earthquake (Ms=7.6) caused 2,400 deaths, more than 8000 casualties and over 10 billion US\$ of economical loss in Taiwan(Chang et al. 2005). 30% of the total fatalities (officially 87,350) had been victims of co-seismic landslides due to the Kashimir earthquake (Ms=7.6) (Havenith and Boureau 2010). In this chapter, we take the 2008 Wenchuan Earthquake (Ms=8.0) as example to discuss this issue.

#### **2.1 The 2008 wenchuan earthquake**

The earthquake had a magnitude of 7.9 Ms, occurred in Sichuan Province, China at 14:28 CST on 12 May 2008. The epicenter is located Yingxiu town (30.986°N, 103.364°E), Wenchuan County. The focal depth is about 12 km according to the report by the China Earthquake Administration (CEA).

The earthquake occurred along the Longmenshan fault (LMSF) zone at eastern margin of the Tibetan Plateau, adjacent to the Sichuan Basin as shown in Fig. 2 (Gorum et al., 2011). The fault belt is a series of faults striking in a northeast direction, on a North-South zone of high topographical and geophysical gradients between the Tibet Plateau on its western side and the Yangzi Platform on its eastern side. Seismic activities concentrated on its midfracture (known as Yingxiu-Beichuan fracture). Starting from Yingxiu, the rupture propagated unilaterally towards the northeast at an average speed of 3.1 kilometers per second, generating a 300-km and a 100-km long surface rupture along the Yingxiu-Berchuan and Pengguan faults, respectively (Huang et al., 2011a). The duration was as long as 120 seconds and the maximum displacement amounted to 9 meters.

Official figures, released by China News www.chinanews.com, on July 21, 2008 12:00 CST show that 69,197 are confirmed dead, 374,176 injured, and 18,222 listed as missing. The earthquake destroyed 5,362,500 and seriously damaged 21,426,600 houses, left about 4.8 million people homeless (Cui et al., 2009, Tang et al., 2011b). Approximately 15 million people lived in the affected area. It was the deadliest earthquake to hit China since the 1976 Tangshan earthquake, which killed at least 240,000 people.

and lead to debris flow or downstream flooding. Also, since the landslide debris can be removed into a valley or a ravine by excessive precipitation, it is easy to form debris flow,

In this chapter, we take the 2008 Wenchuan Earthquake (Ms=8.0) as an example to discuss the earthquake induced chain disasters. The characteristics of the earthquake induced landslides are summarized including the discussion of the landslide dams. A landslide susceptibility analysis is carried out and a possible long run-out mechanism is proposed for the study. The characteristics of the debris flows arising from the earthquake are summarized. An approach of simulating debris flow is proposed for predicting the movement behaviours of potential debris flow arising from earthquake. A practical

A strong earthquake can induce a large amount of landslides and cause very serious property damage and human casualties. This phenomenon was recorded in ancient China dated back to 1789 BCE, and in ancient Greece 2373 years ago (Keefer, 2002). There have been many reports about the very serious damages caused by the earthquake induced landslides for the last few decades. For example, 9,272 landslides induced by the 1999 Chi-Chi earthquake (Ms=7.6) caused 2,400 deaths, more than 8000 casualties and over 10 billion US\$ of economical loss in Taiwan(Chang et al. 2005). 30% of the total fatalities (officially 87,350) had been victims of co-seismic landslides due to the Kashimir earthquake (Ms=7.6) (Havenith and Boureau 2010). In this chapter, we take the 2008 Wenchuan Earthquake

The earthquake had a magnitude of 7.9 Ms, occurred in Sichuan Province, China at 14:28 CST on 12 May 2008. The epicenter is located Yingxiu town (30.986°N, 103.364°E), Wenchuan County. The focal depth is about 12 km according to the report by the China

The earthquake occurred along the Longmenshan fault (LMSF) zone at eastern margin of the Tibetan Plateau, adjacent to the Sichuan Basin as shown in Fig. 2 (Gorum et al., 2011). The fault belt is a series of faults striking in a northeast direction, on a North-South zone of high topographical and geophysical gradients between the Tibet Plateau on its western side and the Yangzi Platform on its eastern side. Seismic activities concentrated on its midfracture (known as Yingxiu-Beichuan fracture). Starting from Yingxiu, the rupture propagated unilaterally towards the northeast at an average speed of 3.1 kilometers per second, generating a 300-km and a 100-km long surface rupture along the Yingxiu-Berchuan and Pengguan faults, respectively (Huang et al., 2011a). The duration was as long as 120

Official figures, released by China News www.chinanews.com, on July 21, 2008 12:00 CST show that 69,197 are confirmed dead, 374,176 injured, and 18,222 listed as missing. The earthquake destroyed 5,362,500 and seriously damaged 21,426,600 houses, left about 4.8 million people homeless (Cui et al., 2009, Tang et al., 2011b). Approximately 15 million people lived in the affected area. It was the deadliest earthquake to hit China since the 1976

seconds and the maximum displacement amounted to 9 meters.

Tangshan earthquake, which killed at least 240,000 people.

and then create a debris dam sometimes.

simulation is carried out for verifying the approach.

**2. The earthquake induced landslide** 

(Ms=8.0) as example to discuss this issue.

**2.1 The 2008 wenchuan earthquake** 

Earthquake Administration (CEA).

Fig. 2. The 2008 Wenchuan earthquake, LMSF and aftershocks. (modified from United States Geological Survey [USGS], 2008)

#### **2.2 The landslides induced by the earthquake**

The earthquake occurred in a mountainous region, where the geological and topographical features and climate conditions are very complex. The response to the ground shock was very strong. The recorded peak ground acceleration of local site reached to 2.0g (Huang et al., 2011b). Because of the complex terrain and climate conditions, the quake induced as many as 56,000 landslides (Dai et al., 2011). It is estimated that over one third of the total lost from the 2008 Wenchuan earthquake was caused by the earthquake induced landslides. Therefore, the secondary chain disaster induced by the 2008 Wenchuan earthquake is much more serious than the 1976 Tangshan earthquake.

Earthquake Induced a Chain Disasters 387

**No. Name Place Area /m2 Distance to fault /m Wall location**  25 Caocaoping Anxian 354,046 660 Hanging wall 26 Miepengzi 3# Mianzhu 353,817 600 Hanging wall 27 Laoyinggou Anxian 353,242 1,050 Hanging wall 28 Huoshigou Anxian 322,155 1,400 Hanging wall 29 Zhangjiashan Anxian 306,576 6,000 Foot wall 30 Macaotan Mianzhu 305,989 2,700 Foot wall 31 Xiejiadianzi Pengzhou 294,256 1,100 Hanging wall 32 Shibangou 2# Qiangchuan 288,305 2,400 Hanging wall 33 Huishuituo Pengzhou 270,980 4,200 Hanging wall 34 Dazhuping Anxian 270,692 540 Hanging wall 35 Miepengzi 2# Mianzhu 262,520 600 Hanging wall 36 Heshangqiao 3# Dujaingyan 257,635 10,400 Hanging wall 37 Muguapingcun Shifang 256,340 900 Foot wall 38 Miepengzi 1# Mianzhu 255,296 600 Hanging wall 39 Dongxigou Beichuan 246,020 2,200 Hanging wall 40 Yaozigou Pingwu 242,553 800 Hanging wall 41 Baichaping Dujaingyan 241,874 4,700 Hanging wall 42 Changping Pengzhou 224,645 2,400 Hanging wall 43 Baodili Qiangchuan 222,157 700 Hanging wall 44 Xiaomuling Mianzhu 218,705 2,450 Hanging wall 45 Heshangqiao 1# Dujaingyan 214,020 10,900 Hanging wall 46 Baishuling Beichuan 208,968 4,350 Hanging wall 47 Dawan Beichuan 203,959 2,150 Hanging wall 48 Baiguoshu Beichuan 203,246 1,000 Hanging wall 49 Zengjiashan Mianzhu 198,165 11,350 Foot wall 50 Zhangjiagou Beichuan 196,299 640 Hanging wall 51 Zhaojiaqu Qiangchuan 193,153 1,300 Hanging wall 52 Heitanzi Anxian 182,452 8,900 Foot wall 53 Anleshan Beichuan 180,809 1,140 Hanging wall 54 Yangshangou Beichuan 177,361 1,300 Hanging wall 55 Xiaotianchi Mianzhu 175,758 8,200 Foot wall 56 Yanyangcun Beichuan 174,008 1,600 Foot wall 57 Shicouzi Pingwu 169,540 0 Hanging wall 58 Chenjiaping Anxian 169,368 1,050 Hanging wall 59 Wangyemiao Dujaingyan 167,980 9,300 Hanging wall 60 Jiadanwan 1# Dujaingyan 166,643 7,900 Hanging wall 61 Jinhelingkuang Mianzhu 159,848 2,800 Foot wall 62 Fengyanzi Beichuan 158,468 0 Foot wall 63 Changtan Mianzhu 151,094 6,670 Foot wall 64 Weijiagou Beichuan 150,818 450 Hanging wall 65 Xiaogangjian Mianzhu 149,074 6,280 Foot wall 66 Baiyanshan Qiangchuan 147,940 4,300 Hanging wall 67 Guoniucun Beichuan 147,554 3,000 Hanging wall 68 Heshangqiao 2# Dujaingyan 147,394 9,600 Hanging wall 69 Bazuofen Anxian 146,272 11,000 Foot wall 70 Tiangengli Qiangchuan 144,729 1,400 Foot wall
