How the earthquake in Myanmar in Bangkok Skinkratzer shook

More than 600 miles separated the epicenter of the earthquake on Friday in Myanmar from the Wolkskrats of Bangkok, which tumbled and fluctuated on the skyline of the huge metropolis. A 33-story high-rise in construction even collapsed. How could the shaking in Bangkok, the Thai capital, were associated with an earthquake?

The answer includes carbon -resistant seismic waves, which are able to move huge distances and to influence high -rise buildings.

When a large earthquake hits, it radiates different frequency of shaking at the same time. Some produce a quick back and forth, other low-frequency fluctuations.

This was true on Friday when the earthquake in Myanmar produced violent, high -frequency seismic waves; They destroyed low buildings, Buddhist pagodas and other structures near the quake’s epicenter, just outside of Mandalay, Myanmar’s second largest city. Many of the destroyed places were made with bricks and masonry, brittle materials that are susceptible to this type of tremors.

When they are released from an earthquake, the seismic waves spread with high frequency inside the earth where they dissolve. In contrast, low frequency waves travel along the earth’s crust and for larger distances.

During the Denali earthquake of 7.9 in Alaska in 2002, the waves drove so far with a low frequency that they harmonized water in swimming pools and ponds to Texas and Louisiana – but almost half an hour, according to NASA.

These types of seismic waves also have a special response in high buildings.

Similar to tuning forks that produce different noises depending on the size, buildings react differently to earthquakes depending on the design and in particular their size.

A 10-story building can fluctuate from one side to side for a second during an earthquake, while a 50-story building can take five seconds to complete the same movement, a nausea that arises back and forth.

Low seismic waves were a key factor for an earthquake in 1985, when almost 900 buildings in Mexico city, partly or completely collapsed, were in the capital of the nation. The extensive destruction initially confused Seimologists and engineers, since the epicenter of the 8.0 Magnites was relatively far away, more than 200 miles west of the city.

They came to the conclusion that the seismic waves with special strength through the city’s clay and silk floors were resonance with special strength, an aggravating factor in the quake and its consequences.

A similar dynamic was in the game last Friday. When the low frequency pulsed over the mainland in Southeast Asia, it was reinforced in and around the Thai capital, since the city is built on the soft soils of Chao Phraya River Delta.

In recent years, scientists have indicated that they have underestimated the potential of these soft soils to make earthquakes more dangerous. Engineers compare the dynamics with the construction of a building on a bowl with jell-o.

In addition to Bangkok and Mexico City, Los Angeles, downtown San Francisco, Seattle and Tokyo are all cities that are exposed to these so-called pelvic effects that can multiply the destructive power of earthquakes, especially at low frequencies.

In Mexico city, the frequencies of seismic waves in 1985 were decisive to understand the damage caused by the earthquake. A team of American scientists who were completed in a report by the Ministry of Commerce in 1987 that most of the serious damage “was limited to buildings in the altitude of seven to 18 floors”. The reason for this is a combination of seismic waves with a lower frequency that reaches the city and the construction that was susceptible to these frequencies.

The report found that “older, older masonry buildings generally cut off well, as well as the massive colonial churches and government offices from stone masonry.” Paradoxically, these are the types of buildings that include engineers most susceptible to shake near the episcent of earthquakes.

According to Thomas H. Heaton, an emeritus professor at the California Institute of Technology, which examined the effects of earthquakes in large magicians for five decades, many American engineers in the 1950s avoid the construction of high -rise buildings in earthquake attacks.

The prevailing wisdom was to build stronger, stiffer buildings. However, this changed over the decades and today’s skyscrapers are more flexible.

According to Dr. Heaton works the flexible design of modern skyscrapers well with earthquakes of sizes around 6, which occur more often. However, it is very concerned about the consequences of less often, larger quakes that have highlighted the susceptibility of high buildings. This roster includes an earthquake of 7.8 magnitude, in which more than 50,000 people were killed in Turkey two years ago.

A massive rejection of a modern city – a direct hit – would be devastating for high buildings, regardless of the technical precautions, says Dr. Heaton.

The violent movement of the soil in the guilt, which document As seismologists call it, the basis of a high increase would quickly shift and the upper floors may not be supported, he said.

“If you take the basis of a building and move it by several meters in less than a few seconds, a civil engineer can do almost nothing so that a building remains upright,” he said. “I would definitely not want to be in a really high building during a large size.”