When is Los Angeles considered uninhabitable?

Risk of flooding: The ground is sinking under the feet of the Californians

08/06/2020 - The latest measurements show: In addition to the east coast, the west coast of the USA is also affected by subsidence. Densely populated areas in California are particularly at risk. Four already low-lying metropolitan regions are particularly affected: San Francisco, Monterey Bay, Los Angeles and San Diego, as shown by a study by researchers at Arizona State University, which the science magazine scinexx first reported. The area at the San Francisco airport is decreasing by around ten millimeters per year. This could make the airport unusable in the long term.

San Francisco lies above the San Andreas Fault, where two tectonic plates slide past each other and which repeatedly causes earthquakes. Subsidence in the floor is also a consequence of the slab displacements. Compression of sedimentary rocks also occurs under the San Francisco airport. The formation of new sediments in the soil leads to compression and thus drainage of the sediment layers underneath. This makes for sinking floors.

Humans also cause sinking floors

While the subsidence in the San Francisco area is due to natural causes, sinking soils in the Los Angeles area are partly man-made. Similar to the east coast, among other things, the excessive abstraction of groundwater causes the subsidence. Between 2011 and 2017, California suffered from an unusually severe and prolonged period of drought. A connection with climate change is considered certain. While people continued to use huge amounts of water for their homes and agriculture, there was insufficient rain to replenish the groundwater reservoirs.

Another contributing factor to the sinking soils in the Los Angeles area is oil production. One of the largest oil reserves in the United States is located under the metropolitan area. It was only with oil that Los Angeles became a well-known and wealthy metropolis. The number of active oil wells in the urban area is estimated at around 3,000. There are also oil fields with production at the gates of the city - on land and on water. So far a gold mine for the city, the oil price plummeted in the corona crisis.

According to researchers at Arizona State University, the soil in the Los Angeles area sinks by two to three millimeters per year due to the extraction of groundwater and oil extraction. At the same time, the global sea level rises over three millimeters per year. Two million people in Los Angeles are increasingly threatened by flooding, the researchers warn. In San Francisco there is another two million.

It affects up to 8.7 million people across California. Flood protection plans are therefore becoming increasingly important. In addition to walls to protect against flooding, attempts are being made to create natural undeveloped space for the water to penetrate. Measures to protect people could cost over $ 100 billion in the coming decades. Even so, some of California's coastal areas are likely to become uninhabitable by 2100. mf