Hazards from the Sichuan earthquake :Hazards from the Sichuan earthquake David Petley Durham University Powerpoint file on my blog – Google: “Petley landslide blog”


Plan for the next 30 minutes :Plan for the next 30 minutes Why was there are earthquake? What happened on the day? What was the damage? What were the short term hazards? What happens next?


5 minutes of intense shaking, 8 minutes in total :5 minutes of intense shaking, 8 minutes in total


Area of shaking :Area of shaking 300 km Moderate damage to well-constructed buildings; difficult to stand Most buildings collapse


Impacts of the earthquake :Impacts of the earthquake Mw = 7.9; depth = 19 km >87,000 thought to have died >69,000 confirmed killed >18,000 “missing “ 374,000 injured >4.8 million homeless (up to 11 million?) Rebuild costs = c.£100 billion


Schools performed very poorly :Schools performed very poorly 7000 classrooms collapsed killing at least 19,000 children


But hospitals and government buildings performed quite well :But hospitals and government buildings performed quite well


Response: destruction to communication structures and roads was a major problem :Response: destruction to communication structures and roads was a major problem


Major challenge – quickly assessing damage and being able to deliver help when roads are blocked :Major challenge – quickly assessing damage and being able to deliver help when roads are blocked


Technology would seem to be the answer, but never delivers in earthquake zones :Technology would seem to be the answer, but never delivers in earthquake zones


Experience of the 1980 Italian Earthquake :Experience of the 1980 Italian Earthquake 94% of survivors were rescued in first 24 hours 35% of people found were still alive 8% of people found were still alive Rescuers need to be on site within a few hours In Italy 90% of rescuers came from the same village as the victim


Immediate key issue 1: Multiple building collapses :Immediate key issue 1: Multiple building collapses People killed or injured People trapped Loss of space to live, eat and sleep


Key issue 2: Large numbers of injured people :Key issue 2: Large numbers of injured people 374,000 injured Arranging medical care proved to be very difficult Need to provide long term care for both physical and psychological injuries


Key issue 3: Water and power :Key issue 3: Water and power Infrastructure for delivering water extensively damaged Electricity generating and transmission capability also greatly damaged


Key issue 4: landslides during and after the earthquake :Key issue 4: landslides during and after the earthquake Huge numbers of landslides occurred Landslide activity continued after the earthquake during aftershocks and in heavy rain


The cost of landslides :The cost of landslides It is estimated that 35% of people killed were buried in landslides In addition, 15% of people who survived the earthquake could not be rescued because landslides blocked roads


Case study: Qushan, Beichuan :Case study: Qushan, Beichuan Town of 40,000 people Regional centre for 160,000 people


Beichuan after the earthquake :Beichuan after the earthquake 13,000 (out of 40,000) people killed


Slide 22:13,000 (out of 40,000) people killed


What happened? :What happened? Landslide 1 Landslide 2 Damage from shaking Air blast


Why so bad? :Why so bad? But the landslide behind the school was known about and had been “fixed”


But there were monsters in the hills… :But there were monsters in the hills…


1786 Dadu River :1786 Dadu River 1st June 1786 Magnitude = 7.75 earthquake 10th June 1786 landslide dam collapsed Flood wave killed 100,000 people downstream


The landslide dams :The landslide dams 45 landslide dams blocked rivers All had to be cleared by building new channels Very difficult to access Very difficult to control flow >1 million people evacuated Tangjiashan, upstream from Beichuan, was the worst


Drained! :Drained!


Draining of lakes was successful, but problems remain :Draining of lakes was successful, but problems remain


What happens next? :What happens next? Three major challenges: The winter The landslides Rebuilding