Earthquakes Dont Kill People; Buildings Kill People.Around three-quarters of all deaths in earthquakes are due to building collapse

20/06/2013 SHARE: MORE PRINT"Earthquakes don't kill people, collapsed buildings do"COPENHAGEN Natural disasters cost the world $100 billion a year, the equivalent of Africas entire yearly infrastructure budget, said a top engineer during her lecture at UNOPS headquarters last week. While Ms da Silva said earthquakes caused 60 percent of disaster-related deaths, - - See more at: https://www.unops.org/english/News/Pages/Earthquakes-dont-kill-people-collapsed-buildings-do.aspx#sthash.J5HRpS2j.dpuf

WHEN THE SHAKINGfrom the Himalayan earthquake reached Kathmandu just before noon on April 25, the Nepalese capital was filled with buildingshastily constructed, poorly builtthat were filled with people.Saturdays earthquake may have caught Nepal by off guard, but that doesnt mean it came asa surprise. You have a massive plate boundary system going under the country of Nepal, saysJanise Rodgers, a structural engineer with Geohazards International, a Palo Alto nonprofit that helps developing countries earthquake-proof their infrastructure. Experts like Rodgers expected thequake because Nepal sits astride a massive continental subduction zone.And the resulting devastation came as no surprise, either, because Kathmandu is filled with buildings not made to stand up to a quake. Seeing modern, vulnerable construction go up without engineering input, building codes, or thought to earthquake design made a lot of people very worried, Rodgers says. The details of earthquake mitigation vary from building to building, but the general principles are:1. Build on bedrock (not sloppy sediment).2. Tie buildings together so they wont be easily knocked over.3. Use steel, or something similarly strong, to reinforce concrete buildings.Proximity to a fault line puts cities in danger of earthquakes. Other accidents of geography can exacerbate a trembler1, but you can predict a citys real risk using a much simpler metric: net worth. In Nepal, you have a rapidly growing population that is very poor, and has basic shelter that is unsafe rather than shelter that is earthquake safe that they cant afford, saysSimon Klemperer, a seismologist at Stanford University.The scary part? Kathmandu isnt unique. Its impossible to predict an earthquake with reliability, of course, but when I asked seismologists what places they worried about the most, these three were among the most compelling examples of places at the intersection of geology and economics.Mexico City, MexicoEven though the Mexican capital is hundreds of miles from any fault lines, it is one of the most seismically threatened cities on the globe. If a quake strikes the coast, people living above the dense bedrock between the Pacific and the capital might only feel a slight tremble. But the capital sits atop an infilled lake, which traps and amplifies seismic waves. And before 1957, the city did not require buildings to be earthquake compliant. Since then, semi-regular tremblers have knocked down a lot of dangerous dwellings (some of which were rebuilt with quake reinforcement), but in the same period the citys perimeter has expanded with shantytowns.On the plus side, Mexico City has a pretty nice early warning system. It 2012, when a7.4 quake hit the coast 200 miles away, the alarm gave many Capitalinos precious seconds to find their way to safety.Istanbul, TurkeyLike Kathmandu and Mexico City, this ancient city connecting Europe and Asia is filled with poor people living in poorly built structures. Unlike those other places, Istanbul is right on top of a dangerous fault zone. The North Anatolian fault is a similar typestrike-slipto Californias San Andreas fault, says Rodgers. And as with its North American twin, experts have been predicting a minimum 7.0 magnitude quake on the North Anatolian for years. But Istanbul does not have anything near Californias stringent earthquake codes. The last quake to hit the citya 7.4 magnitudekilled more than 17,000 people. In the Golden State, the Loma Prieta quakeof comparable strengthshook up the Bay Area, but only killed 63.

New Madrid, USAOn the surface, the middle parts of America do not seem like candidates for seismic disaster. But 200 years ago a small town in southeastern Missouri was the epicenter of several huge earthquakes, some of which reached up to8.0 magnitude. The strongest of these quakes altered the course of the Mississippi River. But because the region has been so quiet in the past century or so, building codes were never brought up to snuff. In 2008, FEMA issued a warning that a modern earthquake of the same magnitude (the odds are around 7 to 10 percent in the next 50 years) would cause, the highest economic losses due to a natural disaster in the United States.Bringing buildings up to codeat home or abroadis costly, but economics is just the language we use to measure the true cost of disaster. When youre talking about earthquake mitigation, youre talking about lives youre saving, says Rodgers. Thats where the real value is: Youre protecting lives. In other words, we should start picking up buildings before they fall down.1. Kathmandu was built in a huge, bowl-like basin atop young, sedimentary rocks. When the quake struck, the basin focused the seismic waves onto the city, which propagated through the soft sediments at amplified levels.CaliforniaWays to rebuild safely and improve resilience are already known, and indeed have been demonstrated: in Concepcion, Chile, the 2010 earthquake was the sixth largest on record, but fatalities remained under 1,000, in large part due to effective implementation of building regulations. And disasters constantly provide new lessons on how to improve resilience, not just of the built environment, but of social and community structures, too.

FACT: Earthquakes are sudden rolling or shaking events caused by movement under the Earths surface.An earthquake is the ground shaking caused by a sudden slip on a fault. Stresses in the earth's outer layer push the sides of the fault together. Stress builds up and the rocks slip suddenly, releasing energy in waves that travel through the earth's crust and cause the shaking that we feel during an earthquake.Faults are caused by the tectonic plates grinding and scraping against each other as they continuously and slowly move. In California, for example, there are two plates - the Pacific Plate (which extends from western California to Japan, including much of the Pacific Ocean floor) and the North American Plate (which is most of the North American continent and parts of the Atlantic Ocean). The Pacific Plate moves northwestward past the North American Plate along the San Andreas Fault at a rate of about two inches per year.Parts of the San Andreas Fault system adapt to this movement by constant "creep" resulting in many tiny shocks and a few moderate earth tremors. In other parts, strain can build up for hundreds of years, producing great earthquakes when it finally releases. Large and small earthquakes can also occur on faults not previously recognized; recent earthquakes in Alabama and Virginia are good examples.Alaska registers the most earthquakes in a given year, with California placing second, until 2014 when a sudden increase in seismicity in Oklahoma pushed it well past California as the second most active in terms of magnitude (M) 3.0 and greater earthquakes. In 2014 there were 585 M3 and greater earthquakes in Oklahoma and about 200 in California. As of April 2015 Oklahoma (260 events) is still well ahead of California (29 events).California, however, has the most damaging earthquakes, including a M6.0 earthquake near Napa in August 2014, because of its greater population and extensive infrastructure. Most of Alaskas large earthquakes occur in remote locations such as along the Aleutian Island chain. Florida and North Dakota have the fewest earthquakes each year.