We shouldn’t just be concerned with rising sea levels. At this time, other modern concerns for humanity are added. For example, cities that are sinking due to their excessive weight. An upward trend.
More people in cities
By 2050, 70% of the world’s population will live in cities. This is how it will happen according to the forecasts Scientist. Geophysicist Tom Parsons is on the United States Geological Survey (USGS). He set about calculating the weight of the San Francisco metropolitan area. He has studied the changes in the solid earth below using numerical modeling techniques. The investigation was published at AGU Advances.
It turns out that the slack under this weight is not insignificant. This is in addition to other causes of urban subsidence, such as B. Groundwater pumps. The American city of San Francisco, built on the coast of the ocean, may have sunk by up to 80 millimeters over time.
“The world population is moving disproportionately towards the coast. This additional drop, combined with the expected rise in sea level, can increase the risk associated with flooding, ”Parsons writes in his article.
According to Parsons, all of the city’s buildings and their contents weigh around 1.6 trillion kilograms. This equates to around 8.7 million Boeing 747s, excluding transport infrastructure, vehicles and people.
The same type of subsidence is likely to occur in other parts of the world. However, this depends in part on the local geology. It might be enough to bend the lithosphere on which the city center resides and even change the relative levels of the fault blocks. These are the boulders that make up the surface of the earth.
“The specific results for the San Francisco Bay Area are likely to apply to any major urban center. With different meanings, of course, ”explains Parsons.
Many details remain to deepen the study of cities sinking under their weight. ‘It should be possible to improve the methods presented here using satellite or aerial imagery. That way, we would be doing more detailed analyzes in likely floodplains, ”summarizes Parsons.