Could an earthquake monster sink parts of the northwest of the Pacific?
A new study is feeding speculation and fear about the risks of an important earthquake in the Cascadia subduction zone, including mass floods in California.
Sitka fir bumps, drowned from the duration of the subsidence, an earthquake in a subduction zone about 1,600 years ago, in Neskowin, mineral.
Marli Miller/UCG/Universal Images Group through Getty Images
The headlines of fear on the northwest of the Pacific that sink into the sea are circulating online, with warnings that a large earthquake was expected in the notorious Cascadia subduction zone.
What is behind this new alarm? Fortunately, research has not discovered a new risk of Seattle becoming the lost city of Atlantis. Instead, scientists have examined the combined effects of two well -known phenomena: the increase in the level of the sea of climate change and the probable consequences of an important earthquake in the region. It was already known that the sea level along the northern coast of California, Oregon and the state of Washington is estimated that it will increase from 1.3 to 2.9 feet by 2100 due to a heating climate. It was also known that an earthquake of magnitude 8 or high in the area could be the coast to fall to 6.5 feet. What the new study, published on April 28 in the Proceedings of the National Academy of Sciences of the USA.“ Add an understanding of how much additional land would end with a high risk of floods due to the thesis two combined threats.
Why is sea level increase important?
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While the east coast is already seeing the effects of beach erosion and the increase in sea level, northwest of the Pacific (UNEP) has been protected by its geology, like this. The coast that extends from northern California to the island of Vancouver in the British Columbia is located in a subduction zone where the sliding of Juan de Fuca, Explorer and Gorda Oceanic Slates surpassed the parts of North America that make parts of the moving. At this time, the fault system is silent, which means that it has not had a large earthquake for more than 300 years, and the coast is gradually increasing by a few inches of inch every year. This geological elevation, a consequence of the interactions of the tectonic plates, exceeds the increase in sea level in many areas, so the UNW has relatively protected bone of effects such as extreme flood events or coastal erosion.
But in the last 7,000 years or so, at least 11 main earthquakes have hit the Cascadia region where these failures reside. The last of these tremors occurred in 1700, and geologists can still see evidence that the coast decreases between 1.6 and 6.5 feet in the blink of an eye. “We have these really rooted organic soils that are suddenly covered by this really clean tide mud, indicating that they were suddenly fallen and were buried and basically turned to tidal floors,” says Tina Dura, coastal geologist of Virginia Tech and first author of the new study.
Hard says that no one had really studied, it was the combined effect of this sudden sinking and the slowest flood falls due to the increase in sea level.
How much or Cascadia will become prone to floods?
Hard and his colleagues observed earthquake scenarios that would produce different sinking ranges, from 1.6 to 6.5 feet. They also compared the effects of such earthquake at current sea level with those of the forecast sea for 2100. At that time, the increase in sea level will be expected to exceed the geological elevation of the UNW and can reach up to 2.9 feet.
The team discovered that if an earthquake that captivated more than six sinking feet would occur today, the 100 -year flood plain in cascadia estuaries would expand in 115 square miles. If this earthquake occurred in the year 2100, with the additional pressures of the increase in sea level, those estuaries would expand in 145 square miles. That would be triple the area prone to floods that is good today.
How worried should we be?
In the case of an earthquake of magnitude 8 in Cascadia, the subsidence would not be the first problem in anyone’s mind. A large underwater earthquake could cause a devastating tsunami that would immediately threaten lives and structures. The new study focuses on areas within six elevation feet of the current flood plain of 100 years, says Dura, and the Tsunami driven by the earthquake could be more than 30 feet high.
A good comparison could be the earthquake and Tsunami of Sumatra 2004 that killed more than 227,000 people around the Indian Ocean or the T&ACR 2011; Hoku’s earthquake and tsunami that killed more than 16,000 in Japan. Both caused sinking, but the severity of the initial disaster eclipsed the groups on coastal depression.
However, understanding the sinking is important for preparation, he says hard. Municipal planners can avoid building new electrical substations or wastewater treatment plants in areas that could become flood plains. (A flood plain of 100 years has a 1 percent flood possibilities every year). The floods of bridges, roads and low airports in tide stores could board and rescue the Atates. And many people can find that the property that was safe from floods is now a regular flood, particularly in accumulation areas such as Seaside County, Oregon, Gearhart, Or. And Grays Harbor in the state of Washington, says Dura.
“The tsunami is a process that takes minutes after the earthquake,” he says, “while, once the tsunami goes back, we will still have the land level that has fallen and changed the mark of the flood plain.”
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