# 24 Global Death and Construction: Earthquakes on an Urban Planet Dr. Roger Bilham March 21, 2003 Produced by and for Hot Science - Cool Talks by the Environmental Science Institute. We request that the use of these materials include an acknowledgement of the presenter and Hot Science - Cool Talks by the Environmental Science Institute at UT Austin. We hope you find these materials educational and enjoyable.
Global Death and Construction: Earthquakes on an Urban Planet Dr. Roger Bilham Cooperative Institute for Research in Environmental Studies Department of Geological Sciences, University of Colorado
What Causes Earthquakes Where People Live (recently too many people) Violent Deaths (8 million earthquake fatalities in the past millenium) Statistics and Predictions (the 1 million fatality extreme event) Road Map to Killer Buildings India's 500 Million at Risk (past disasters, worse to come, and why) How People Die (criminal contractors) Rooms for Optimism (3 billion dwelling units under construction in the next 50 years)
Earthquakes occur when two rock masses slide past each other.
Earthquakes occur when two rock masses slide past each other.
Earthquakes occur when two rock masses slide past each other. http://www.iris.edu/gifs/animations/faults.htm
1906 San Francisco quake
100 mile long cracks from two recent quakes ChiChi earthquake Taiwan Sept. 1999 M=7.8 Izmit earthquake Turkey Aug. 99 M=7.4
Most earthquakes happen at plate boundaries. the bigger the fault- the larger the quake fast plate motions more frequent earthquakes can t stop earthquakes http://www.iris.edu/seismon/
The Target: Urban Society
Pre 1600 Urban agglomerations (towns > million)
1950 supercities > 2 million megacities > 8 million
2000 140 supercities > 2 million 28 megacities > 8 million (325 cities > 1 million) 15 2050 urban population >5 billion ( half the world total).
8 million earthquake deaths in the past 1000 years. 50% world s supercities near future M>7.5 earthquakes. > 10,000 dead > 100,000 dead > 300,000 dead convergent & transform more than 90,000 dead plate boundaries
Deaths per earthquake 500 Years of Earthquake Fatalities 10 6 10 5 10 4 10 3 10 2 10 1 1600 1700 1800 1900 2000 Year
Earthquake Fatalities and Population Growth 5 4 3 2 Cumulative number of earthquake fatalities(millions) Population (billions) 1 Fatalities from earthquakes with fewer than 30 thousand deaths 1600 1700 1800 1900 2000
Cumulative earthquake fatalities since 1600 Earthquake Fatalities from Moderate Events (<30,000 deaths/event) 1 Million 8000 /yr 4000 /yr 2000 /yr Rates doubled twice in 250 years! 1600 1800 2000 Year Prediction in 1997 was 8000 fatalities/yr: 1998-2002 average was 10,500 fatalities/yr
Fatalities (cumulative millions) When we include highly lethal events 3 20,000 / year 2 Tangshan 1976 250,000-500,000 fatalities 1 Fatalities from events with fewer than 30,000 deaths/event 1900 2000 2100 Year
Tangshan 1976 Can we predict frequency of extreme events?
Number of earthquakes How do we predict infrequent events? Incomplete reporting 2 100 Past five hundred years 10 Twentieth century 1 10 100 1000 10000 100000 1000000 Fatalites per earthquake
Number of earthquakes per century Mf predictability each century 100 2 Each year one event kills 100 400 year average Every 5 yrs one event kills 10,000 10 Every 2 years one event kills 1000 Every century an earthquake kills 300,000 2 1 Mf=2 3 4 5 10 100 1000 10000 100000 Fatalites per earthquake
Number of earthquakes per century 100 10 2 7 6 5 4 3 2 7 6 5 4 3 400 year average but 0.3M is an underestimate because cities doubled in last century and will double again in the next! Is a hundred year megaquake now possible? 1 2 Mf=2 3 4 5 10 100 1000 10000 100000 Fatalites per earthquake
A Look Into an Urban Seismic Future Large Populations - Large Cities
Indian Earthquakes in the Past 30 Years
1935 1905 1803 1833 1934 1897 1950 1945 1819 1737 1881 1941 Earthquakes of greater than M=7.5
EARTHQUAKE FATALITIES: INDIA 1800-2000 1000/year Population 1000 million 10,000 dead
Himalayan earthquakes are caused by the slip of India beneath Tibet. India Himalaya Tibetan Plateau India
Every few hundred years part of the Himalaya approaches failure critical stress Tibet India
and a great earthquake ruptures the plate boundary. 2-8 m surface rupture India great earthquake 1.5 m co-seismic subsidence Tibet
Example:1505 earthquake in W. Nepal 10 m M=8.2 1600 2 m M=7.4 1700 4 m M=7.6 time 1800 6 m M=7.8 1900 8m M=8 2000 The longer we wait the bigger the 'quake.
. Himalayan rupture potential (200 year window) Himalayan Seismic Hazard
Observations A. Historic void - Sikhim/Assam B. 16th century rupture Kashmir to Kumaon C. Renewal rate 1.8 m/century 1842 24 Sept1501 7 July1505 Sept 1555 KASHMIR Problems: 1. no surface rupture linked to any historical earthquake 2. M<7.9 events insufficient to rupture plate boundary? 3. M>8.2 events may be necessary every 500-700 years. KUMAON M>8.2 W. NEPAL M=8.1 1934 E. NEPAL SIKHIM 1713 M=8.5 ASSAM Himalayan Earthquakes 1255-1950
2000 1900 1800 1700 7.5 Quetta 7.5 Sale 7.8 7 Kangra 600 km Mw=8.2 7.5 7.8 8.1 NepalBihar? 7.4 8.5 8.0 Sikhim Shillong 7.6 Bhutan Assam 1600 1500 7.4 Kabul 7.6 7.2 Kashmir 8.2 1400 1300?
1713. 5.5 m Himalayan rupture potential (500 year window) Revised Himalayan Seismic Hazard?
Delhi 13 million 25 km Jaipur Agra Kanpur 3 million 75.00 76.25 77.50 78.75 80.00 81.25
Cross Section of the Indian Plate Outer trough -40 m Central Indian Plateau +450 m Gangetic trough -4 km Himalaya Tibet Latur Bhuj Flexed Indian Plate Jabalpur Udaypur Viscous Mantle
Text Population at risk 500 million
10 8 World population (billions) 6 4 2 Dwelling 1950-2050 units The 4 people/house age of construction 500 1000 1500 2000 years A.D.
Adipazari averting disaster
Many dwellings now collapse due to column failure.
how columns fail. Columns without stirrups can be crushed
A column with many strong stirrups cannot explode.
World population (billions) 10 8 6 4 2000-2050 The age of construction Three billion dwellings!! 2 500 1000 1500 2000 Earthquakes don t kill peoplebuildings do.
Acknowledgements: Environmental Science Institute at The University of Texas CIRES - Cooperative Institute for Research in Environmental Sciences Seismological Society of America
Dr. Roger Bilham Dr. Roger Bilham received his Ph.D. in Geophysics from Cambridge University in 1971. Dr. Bilham s research has focused in experimental measurements of deformation of mountain ranges, volcanoes and earthquake regions (GPS, absolute-gravity, creep meters and tiltmeters) in Asia, California, New Zealand, Venezuela and Mexico, and theoretical studies of deformation mechanisms causal to plate-boundary and intraplate earthquakes. He was awarded the Guggenheim Fellowship in 2000 and the IRIS/SSA Distinguished Lecturer award in 2002. Dr. Bilham is a member of Seismological Society of America, the American Geophysical Union, the Geological Society of America and the Royal Geographical Society. He is currently writing two books, a book on urban earthquakes, and a book on Mt. Everest. Dr. Bilham has also written articles in magazines such as Discover, Earth magazine and the Economist.