How do you stop the flow of lava?
Japan’s radical bid to fend off tsunamis with giant, 400km sea wallMARCH 23, 20158:40AM0-5095Workers build sea walls in Rikuzentakata, Iwate Prefecture, northeastern Japan. Some are five storeys high in places.FOUR years after a towering tsunami ravaged much of Japan’s northeastern coast, efforts to fend off future disasters are focusing on a nearly 400-kilometre chain of cement sea walls, at places nearly five storeys high.Opponents of the 820 billion yen ($6.8 billion) plan argue that the massive concrete barriers will damage marine ecology and scenery, hinder vital fisheries and actually do little to protect residents who are mostly supposed to relocate to higher ground. Those in favour say the sea walls are a necessary evil, and one that will provide some jobs, at least for a time.In the northern fishing port of Osabe, Kazutoshi Musashi chafes at the 12.5-meter (41-foot)-high concrete barrier blocking his view of the sea.“The reality is that it looks like the wall of a jail,” said Musashi, 46, who lived on the seaside before the tsunami struck Osabe and has moved inland since.0-2215Local residents Kazutoshi Musashi, left, and Shigeru Chiba look at the 12.5-metre-high concrete barrier under construction in the northern fishing port of Osabe, in Rikuzentakata, Iwate Prefecture.Source:APPouring concrete for public works is a staple strategy for the ruling Liberal Democratic Party and its backers in big business and construction, and local officials tend to go along with such plans.The paradox of such projects, experts say, is that while they may reduce some damage, they can foster complacency. That can be a grave risk along coastlines vulnerable to tsunamis, storm surges and other natural disasters. At least some of the 18,500 people who died or went missing in the 2011 disasters failed to heed warnings to escape in time.Tsuneaki Iguchi was mayor of Iwanuma, a town just south of the region’s biggest city, Sendai, when the tsunami triggered by a magnitude-9 earthquake just off the coast inundated half of its area.A 7.2-metre-high sea wall built years earlier to help stave off erosion of Iwanuma’s beaches slowed the wall of water, as did stands of tall, thin pine trees planted along the coast. But the tsunami still swept up to 5 kilometres inland. Passengers and staff watched from the upper floors and roof of the airport as the waves carried off cars, buildings and aircraft, smashing most homes in densely populated suburbs not far from the beach.The city repaired the broken sea walls but doesn’t plan to make them any taller. Instead, Iguchi was one of the first local officials to back a plan championed by former Prime Minister Morihiro Hosokawa to plant mixed forests along the coasts on tall mounds of soil or rubble, to help create a living “green wall” that would persist long after the concrete of the bigger, man-made structures has crumbled.0-4873A woman walks near sea walls being built in Rikuzentakata, Iwate Prefecture, northeastern Japan.Source:AP“We don’t need the sea wall to be higher. What we do need is for everyone to evacuate,” Iguchi said.“The safest thing is for people to live on higher ground and for people’s homes and their workplaces to be in separate locations. If we do that, we don’t need to have a ‘Great Wall,”’ he said.While the lack of basic infrastructure can be catastrophic in developing countries, too heavy a reliance on such safeguards can lead communities to be too complacent at times, says Margareta Wahlstrom, head of the UN’s Office for Disaster Risk Reduction.“There’s a bit of an overbelief in technology as a solution, even though everything we have learned demonstrates that people’s own insights and instincts are really what makes a difference, and technology in fact makes us a bit more vulnerable,” Wahlstrom said in an interview ahead of a recent conference in Sendai convened to draft a new framework for reducing disaster risks.In the steelmaking town of Kamaishi, more than 1,000 people died in the 2011 tsunami, but most school students fled to safety zones immediately after the earthquake, thanks to training by a civil engineering professor, Toshitaka Katada.00Local leader Takeshi Konno points at a construction site for the giant sea walls.Source:APThe risk is not confined to Japan, said Maarten van Aalst, director of the Red Cross/Red Crescent Climate Center, who sees this in the attitudes of fellow Dutch people who trust in their low-lying country’s defenses against the sea.“The public impression of safety is so high, they would have no idea what to do in case of a catastrophe,” he said.Despite pockets of opposition, getting people to agree to forego the sea walls and opt instead for Hosokawa’s “Great Forest Wall” plan is a tough sell, says Tomoaki Takahashi, whose job is to win support for the forest project in local communities.“Actually, many people are in favour of the sea walls, because they will create jobs,” said Takahashi. “But even people who really don’t like the idea also feel as if they would be shunned if they don’t go along with those who support the plan,” he said.While the “Great Forest Wall” being planted in some areas would not stave off flooding, it would slow tsunamis and weaken the force of their waves. As waters recede, the vegetation would help prevent buildings and other debris from flowing back out to sea. Such projects would also allow rain water to flow back into the sea, a vital element of marine ecology.04283A Shinto shrine gate remains standing on a hill as sea walls are being built in the waterfront area in Rikuzentakata.Source:APSome voices in unexpected places are urging a rethink of the plan.Prime Minister Shinzo Abe’s wife, Akie, offered numerous objections to cementing the northeast coast in a speech in New York last September. She said the walls may prevent residents from keeping an eye out for future tsunamis and would be costly to maintain for already dwindling coastal communities.“Please do not proceed even if it’s already decided,” she said. Instead of a one-size-fits-all policy, she suggested making the plan more flexible. “I ask, is building high sea walls to shield the coast line really, really the best?”Rikuzentakata, a small city near Osabe whose downtown area was wiped out by the tsunami, is building a higher sea wall, but also moving many tons of earth to raise the land well above sea level.Local leader Takeshi Konno said no construction project will eliminate the need for coastal residents to protect themselves.“What I want to stress is that no matter what people try to create, it won’t beat nature, so we humans need to find a way to co-exist with nature,” Konno said. “Escaping when there is danger is the most important thing is to save your life.”0-665The lone pine tree that miraculously survived the deadly 2011 tsunami among 70,000 trees along the coastline, stands in Rikuzentakata.The tree, which was badly damaged from seawater after surviving the tsunami, was cut down in 2012 and treated for decay after which it was preserved using artificial materials. It was later placed back where it was found to stand as a symbol of hope and survival.Source:APForget steel and concrete, earthquake 'curtains' could make buildings quake-proofJapan has approximately 1,500 earthquakes a year and its citizens are finding innovative ways to support the country's structuresBy?CLARE DOWDYMonday 22 August 2016A 160-metre roll of the carbon-fibre rope weighs just 12kgHow do you protect buildings in a country bedevilled by earthquakes? Instead of using steel or concrete, a? HYPERLINK "" Japanesetextile firm turned to carbon-fibre ropes. The company,?Komatsu Seiren, had developed a high-tensile twine from carbon-fibre composite.Seeking to reinforce the structure of its new showroom and laboratory in Nomi, it asked Japanese architects Kengo Kuma and Associates to use rods of the material to anchor it. "Since the carbon fibre is tough and pliant, they approached us with an idea of utilising it to render the building quake-resistant," says Shun Horiki, the project's lead?architect.?The team attached 1,031 rods to the roof and tethered them to the ground. "The principle is quite straightforward," says Horiki. "When the building jolts left, the rod on the right pulls it back, and vice versa. A curtain of 2,778 rods inside adds a further layer of stability.This diagram shows tensile strength applied to the exterior rods during an earthquake. Red shows the areas of most tension, ranging through to yellow and then blue, where there is least"The carbon mesh inside and the drape outside help restrain the horizontal force of the?earthquake," he says.Before attaching the rods, Kengo Kuma and Associates enhanced the strength of the building's parapet in order to resist tensile stress and placed anchors around the structure to prevent the ground from rising up.This is the first time that carbon fibre has been used in this way, but Horiki believes the rods could also be applied to flexible structures such as wooden buildings that "tend to sway horizontally".Building Safer Structures (USGS: U.S. Geological Survey)In this century, major earthquakes in the United States have damaged or destroyed numerous buildings, bridges, and other structures. By monitoring how structures respond to earthquakes and applying the knowledge gained, scientists and engineers are improving the ability of structures to survive major earthquakes. Many lives and millions of dollars have already been saved by this ongoing research. HYPERLINK "" left000 The Transamerica Pyramid in San Francisco, built to withstand earthquakes, swayed more than 1 foot but was not damaged in the 1989 Loma Prieta, California, earthquake.On October 17, 1989, the magnitude 7.1 Loma Prieta earthquake struck the Santa Cruz Mountains in central California. Sixty miles away, in downtown San Francisco, the occupants of the Transamerica Pyramid were unnerved as the 49-story office building shook for more than a minute. U.S. Geological Survey (USGS) instruments, installed years earlier, showed that the top floor swayed more than 1 foot from side to side. However, no one was seriously injured, and the Transamerica Pyramid was not damaged. This famous San Francisco landmark had been designed to withstand even greater earthquake stresses, and that design worked as planned during the earthquake. HYPERLINK "" left000 Earthquakes are a widespread hazard in the United States. Colors show magnitudes of historical earthquakes: red, 7 or greater; orange, 5.5 to 7; yellow, 4.5 to 5.5. The U.S. Geological Survey operates instruments in many structures in the seismically active areas shown. These instruments measure how structures respond to earthquake shaking.?Designing and building large structures is always a challenge, and that challenge is compounded when they are built in earthquake-prone areas. More than 60 deaths and about $ 6 billion in property damage resulted from the Loma Prieta earthquake. As earth scientists learn more about ground motion during earthquakes and structural engineers use this information to design stronger buildings, such loss of life and property can be reduced.To design structures that can withstand earthquakes, engineers must understand the stresses caused by shaking. To this end, scientists and engineers place instruments in structures and nearby on the ground to measure how the structures respond during an earthquake to the motion of the ground beneath. Every time a strong earthquake occurs, the new information gathered enables engineers to refine and improve structural designs and building codes. In 1984 the magnitude 6.2 Morgan Hill, California, earthquake shook the West Valley College campus, 20 miles away. Instruments in the college gymnasium showed that its roof was so flexible that in a stronger or closer earthquake the building might be severely damaged, threatening the safety of occupants. At that time, these flexible roof designs were permitted by the Uniform Building Code (a set of standards used in many states). Many industrial facilities nationwide were built with such roofs. HYPERLINK "" left000 Seismic records (upper right) obtained during the 1984 Morgan Hill, California, earthquake led to an improvement in the Uniform Building Code (a set of standards used in many states). The center of the gym roof shook sideways three to four times as much as the edges. The Code has since been revised to reduce the flexibility of such large-span roof systems and thereby improve their seismic resistance.?Building codes provide the first line of defense against future earthquake damage and help to ensure public safety. Records of building response to earthquakes, especially those from structures that failed or were damaged, have led to many revisions and improvements in building codes. In 1991, as a direct result of what was learned about the West Valley College gymnasium roof, the Uniform Building Code was revised. It now recommends that such roofs be made less flexible and therefore better able to withstand large nearby earthquakes.Earth scientists began recording earthquakes about 1880, but it was not until the 1940's that instruments were installed in buildings to measure their response to earthquakes. The number of instruments installed in strucures increased in the 1950's and 1960's. The first abundant data on the response of structures came from the devastating 1971 San Fernando, California, earthquake, which yielded several dozen records. These records were primitive by today's standards. The first records from instruments sophisticated enough to measure twisting of a building were obtained during the 1979 Imperial Valley, California, earthquake.Today there are instruments installed in hospitals, bridges, dams, aqueducts, and other structures throughout the earthquake-prone areas of the United States, including Illinois, South Carolina, New York, Tennessee, Idaho, California, Washington, Alaska, and Hawaii. Both the California Division of Mines and Geology (CDMG) and the USGS operate instruments in California. The USGS also 442314429800700operates instruments in the other seismically active regions of the nation. HYPERLINK "" left000left000left000 HYPERLINK "" USGS scientists have installed instruments in a variety of structures across the United States to monitor their behavior during earthquakes. Examples shown include a dam, a bridge supporting a large aqueduct, a highway overpass, and a Veterans hospital.?The majority of deaths and injuries from earthquakes are caused by the damage or collapse of buildings and other structures. These losses can be reduced through documenting and understanding how structures respond to earthquakes. Gaining such knowledge requires a long-term commitment because large devastating earthquakes occur at irregular and often long intervals. Recording instruments must be in place and waiting, ready to capture the response to the next temblor whenever it occurs. The new information acquired by these instruments can then be used to better design earthquake-resistant structures. In this way, earth scientists and engineers help reduce loss of life and property in future earthquakes.Mehmet Celebi, Robert A. Page, and Linda SeekinsHow do you stop the flow of lava?By Taylor Kate Brown BBC News, Washington11 September 2014Bottom of FormAuthorities on Hawaii's Big Island have declared a state of emergency as lava from the Kilauea volcano threatens residential communities and roads. Is there any way to stop a lava flow and save the homes in its path?The Sicilians have always been threatened by Mount Etna, the volcano mountain in the north-eastern part of the island. In 1669, resourceful residents of the village of Catania fought back against the all-destructive force of molten lava."Armed with shovels and pickaxes and protecting themselves against heat with wet sheep-skins",?according to one academic account, the Catanians opened an artificial breach, cutting off the lava's path.The residents of nearby Paterno were not pleased. They believed the diversion pointed the lava directly at their own community and decided to stop Catania's attempts. The breach sealed up and the lava continued flowing toward Catania, destroying a large portion of the town.-148856490220It was the modern start to what Dr Shannon Nawotniak, a professor of geology at Idaho State University, calls a "spectacularly poor success rate" of stopping lava.Image: Mount Etna is the second-most active volcano in the worldAt temperatures of about 1,000C (1,832F), lava destroys whatever it touches. Its path is notoriously hard to predict.The ability to impede or redirect lava largely depends on location, resources and luck. Here are four strategies:Bomb itBefore he was a general in World War Two, George S Patton designed a different kind of military campaign - a bombing run on Hawaii's Mauna Loa, the largest volcano on Earth, as it erupted in 1935.As the lava began flowing at a rate of one mile (1.6km) a day towards the city of Hilo, then-director of the Hawaiian Volcano Observatory Thomas Jaggar suggested bombing lava tubes.Lava tubes are cooled and hardened outer crusts of lava which provide insulation for the faster-flowing, molten rock inside. Such a conduit enables lava to move farther and faster.In theory, bombs would destroy the lava tubes, robbing lava of an easy transport channel and exposing more of the lava to the air, slowing and cooling it further.But in practice, while bombs created craters in parts of the tubes, they were soon filled again by the lava. Hilo was instead saved when Mauna Loa stopped erupting.0000Image copyright: APImage caption Lava tubes allows molten rock to move farther than it otherwise wouldLater tests by the US Air Force suggested newer, larger bombs could make more of a difference if they were targeted at the most vulnerable sections of the flow.Cool it with waterOne of the most successful lava stops came in the 1970s on the Icelandic island of Haimey. Lava from the Eldfell volcano threatened the island's harbour and the town of Vestmannaeyjar.For almost five months in 1973, frigid sea water was blasted through cannons towards the advancing lava. As the water hit the superheated rock, it turned into steam, allowing the lava's heat to dissipate.0254000Image Lava stopped in the middle of a street in VestmannaeyjarA fifth of Vestmannaeyjar was destroyed before larger cannons were brought in, but enough of the lava flow was slowed and redirected to save the harbour.In all, 1.5 billion gallons (6.8 billion litres) of water were used.But conditions were right for such an intervention to work - the lava from Eldfell was particularly slow moving and an inexhaustible supply of water was available, Dr Nawotniak says.Build a barrierBack at Mount Etna, an eruption in March 1983 threatened three towns. Barriers of rock and ash were constructed in an attempt to divert the lava. "They were trying to slow it down and direct it downhill," Dr Nawotniak says. One of the first barriers, 18m high and 10m wide, was overrun, but a second barrier blocked lava from moving further west.-9588531242000Image copyrightUSGS Image caption The Sapienza barrier in 1983Two other major barriers kept the flow from reaching the main tourist area of Etna on the eastern side of a valley.The lava missed buildings by metres. One of the barriers, known as Sapienza, had six feet added to it by the lava. But Sapienza and the others held until the eruption ended in August.Add concreteAlmost 10 years later, Etna erupted again, and Italian officials used the lessons of the earlier eruption to save the town of Zafferana. In addition to barriers, workers created an artificial trench to catch lava redirected from a breach made with explosives. That only pushed away part of the lava, so concrete blocks were dumped into the remaining flow, fully diverting its path.But how many of the successful diversions or stops of lava only worked because the eruptions ended when they did? The US Geological Survey suggests that the Iceland and Etna diversions "may not have succeeded had their respective eruptions continued".-11695839101200"You have to be in a wealthy country with a lot at stake to even consider" lava diversion, Dr Nawotniak says, considering the volume of volcanic eruptions and the potential costs."You might buy yourself some time until the volcano stops itself," she says.Image caption The path of lava is difficult to predictDiversion may push lava away from one area only to direct it toward another human settlement. The residents of Paterno knew that well.Dr Nawotniak says she and her fellow geologists see lava diversion as an ultimately losing battle.A better focus, she says, is improving the prediction of volcanic eruptions."That way we can give people the best possible chance to move on their own terms," she says.374372260133Image caption A house submerged in ashThe Icelandic eruption 41 years ago buried hundreds of houses. Archaeologists have been uncovering what remained of the buildings, giving the island the nickname "Pompeii of the North". An entire museum has been built around the remains of one of the homes. For some people on the island, however, uncovering the remnants of a traumatic past has been difficult.Iceland's 'Pompeii' emerging from the ashBuilding Earthquake Resistant Buildings is best for the Environment and the PeopleFebruary 24th, 2011?by?Guest Contributor?The?tragic earthquake in Christchurch, New Zealand, has left much of the city in ruins, killed more than 75, and left hundreds missing. Even as survivors continue to be dragged out of the rubble, and survivors reel in their shock, it’s worth looking forward to how the city might be rebuilt to better deal with disasters like this in the future. Building for disaster resistance might be expensive today, but in the long run it is the very height of environmental and fiscal responsibility, as it prevents the great waste and expense of having to rebuild later. And this is without even considering the steep human cost of poor construction.But first, let us step back and talk a bit about what causes structural damage in earthquakes like the one Christchurch has just experienced. Earthquakes are highly stressful events. Bear in mind that I don’t mean this in the psychological sense, even though this is certainly true, as anyone observing the shocked citizens of Christchurch wandering the streets on the TV can attest. Rather, I mean this in a physical sense; earthquakes place lots of physical stresses upon buildings, particularly lateral stresses due to back and forth motions that conventional buildings are poorly designed to cope with, and when those stresses overcome the structural integrity of a structure, it collapses. There are two ways to deal with this; you can both take a conventional building design, and reduce the stresses acting upon it, or you can change the design to relieve stresses more effectively. Let’s look at each in turn.A conventional building can be simplified as a box on a platform, or foundation.03057The reason this basic design is so common is that it is a good compromise between the cost of construction and materials, and interior volume. But watch what happens if the ground shifts suddenly to the left or right.00-318976332949700Because of conservation of momentum, the top of the building moves more slowly than the bottom, and so if you were to take a snapshot of a box structure during an earthquake, it would look much like this. While a box is very good at resisting gravity, when you add in lateral stresses it no longer has straight, load bearing walls. If the shaking is minor, the building will sway a bit and survive. But if the stresses are greater than that, as you can see in the illustration, this can result in a part of the building that has no real support against gravity. If this state persists for any length of time, the building collapses. And this is assuming that the building is elastic; if it has been made of stiff, but brittle, materials such as brick, the building can actually shatter due to the swaying action itself. One widely practiced solution is called?base isolation, and involves placing a dampening system between the foundation and the load bearing walls. This dampener can be a lead post embedded in rubber, springs, or a set of large, very strong ball bearings in a gently sloped channel.In any case, the dampener takes the lateral stresses, and the building does not collapse. However, the dampeners themselves can be damaged in the process of absorbing this energy. And while it is better for the people to survive than not, it would be best if the building could be saved as well.Another, more recent development, is the use of a large, tuned?pendulum mass damper, attached to the upper floors of the structure, and often equipped with mechanisms to move it actively in opposition to strong forces.-31897727813000Essentially, this works to give a building a sense of balance like we do. This technology functions very well to absorb the damaging stresses by simply moving a very large mass in the opposite direction to the force. The forces cancel out, and the building does not sway and collapse. The benefit of this technology is that it is more durable than technologies that are at the foundation level, and it’s easier to repair since the device itself is not load bearing. Many super skyscrapers in seismically active areas now have an active, tuned pendulum in them. In the case of the?Taipei 101?skyscraper in Taiwan, the pendulum is suspended from the 92nd floor, and weighs a staggering 660 tons! In 2008, the pendulum worked well to cancel out earthquake forces, as seen in this video:0000Taipei 101 Damper movement on 12 May 08But perhaps the answer lies not in augmenting conventional structures, but in adopting unconventional designs. A good place to start would be to ask what sort of structures have proven to be resistant to earthquakes over long periods of time, like thousands of years. Take, for instance, the? HYPERLINK "" Hagia Sophia in Istanbul.0116958Dedicated in 360 AD, the building has served as a church, a mosque, and a museum ever since, despite the fact that the city it is in has been repeated destroyed by violent earthquakes. Why has it survived? Because the greater part of the structure is not a box, it’s a series of domes. Domes (and their planar cousin, the pyramid) distribute lateral forces very well for three reasons. First, and foremost, even movements strong enough to get a dome to sway will not produce areas of the structure that have no support against gravity, because the base is much wider than the top. Second, domes distribute forces in all directions naturally, and thus the design is much better at dissipating energy. And third, most of the mass of a dome is low, and this lower center of gravity greatly reduces the chance of collapse.-605108274900So, why aren’t our cities made up entirely of domes and pyramids? Well, pyramids have less internal volume than an equivalent box, so that’s one reason, thoughmany skyscrapers have been made in a pyrimidal shape in geologically active areas. But domes actually have more volume than an equivalent box, albeit in a form that is a bit harder to utilize. So, in light of this, why are domes so rare?Because, until recently, domes were very hard to build. Basically every piece that goes into a dome has to be custom made, and until the keystone is in place the structure is actually rather fragile. However, two recent building techniques have changed this, and made domes far easier to build, easier, even, than conventional structures.The first technology is the?geodesic dome, a structure composed of repeating icosahedrons covered by a protective skin.The use of repeating geometry allows for large parts of the building to be built from standardized pieces, which both cheapens and simplifies construction, and the geometry allows for the building to be both strong and lightweight. But the geodesic dome has a flaw. The weak point has long been the ‘skin’ itself; glass is too heavy to be easily used for this purpose, and if it breaks free of its frame it can be very hazardous to the people inside, and lighter composites like acrylic pose a fire hazard. As a result, the geodesic dome has become less popular over the past few decades. However, recent?breakthroughs in composite glasses?that are light, strong and fire resistant, may cause a resurgence in this design. Fun fact; the invention of Geodesic domes are usually credited toBuckminster Fuller, but in fact he only developed the mathematics that explains how the structures are so stable. The actual inventor is a German man by the name of?Walther Bauersfeld, who built the first dome of this type for the?Carl Zeiss?company to house a planetarium.0758190The second modern dome technology, one that is quietly becoming more and more popular on both a large and small scale, is the?monolithic dome. Monolithic domes differ from geodesic domes in a few ways; they are very heavy, and they are formed in one piece. Building one requires the use of some sort of form, either a mound of dirt in earlier models, or an inflated?airform in?more recent constructions. After the form is in place, insulation, rebar, and concrete are sprayed onto the inside or the outside of it. As this cures, it forms a single, reinforced piece that makes up the entire structure. Over the past several decades, monolithic domes have proven to be?extremely disaster resistant, defying tornadoes, earthquakes, and cyclones. Due to their largely concrete construction, they are even fire resistant, and should last for hundreds, or even thousands of years if well maintained. Even better, as the technology has matured costs have fallen to the point at which they are comparable, or even cheaper, than conventional structures, and considerably cheaper than conventional earthquake resistant structures. Once you consider how much more?energy efficient?monolithic domes are than conventional structures, it’s hard to deny that they could play an important role in the creation of sustainable, disaster resistant cities. At this point, the only thing holding them back is the NIMBY attitude that is holding back so much sustainable technology. Domes look very futuristic or even weird compared to box structures. But, after a disaster, a standing dome is much better looking than a smoking pile of bricks, so it might be wise to get over it and start building domes everywhere! ................
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