Even the epic rainfall may not be enough to recharge the aquifers of Socal

Although extraordinary rains repeated California in 2023, they barely helped replenish the decades of drought and human pumping, reveals a new study.

About one -third of the water supply in Los Angeles, which is sensitive to long dry magic, comes from groundwater. But in the first three months of 2023, more than a dozen atmospheric rivers – long and narrow weather systems, full of water steam – brought rain on the western coast. Then, in August, Hilary Hilary shed rain over southern California. Across the country, precipitation for the well -measured year for double its average of the 20th century. In total, the January-Gushti rainfall added more than 90 billion liters of water to surface reservoirs in the Los Angeles area.

This moisture almost completely replenish the aquifers near the surface of the region. But the deepest layers that hold water hardly gained any relief, William Ellsworth, seismologist at Stanford University, and his team report February 13 on February 13 Science

To make that appreciation, Ellsworth and his colleagues watched how the water that had been traversed in previously shredded layers of permeable rock affected the speed of seismic waves traveling through them. Previous teams have used ever-present seismic noise from small and human earthquakes such as traffic and industrial activity-to design errors and other underground features.

What many scholars consider seismic noise is “free information, which is there on Earth every day,” says Ellsworth. “Being able to do something with that is really exciting.”

By analyzing the vibrations of different frequencies, Ellsworth and the team can identify any changes due to water infiltration as deep as hundreds of meters below the surface.

Overall, the team notes, only about 25 percent of the water lost by the region’s aquifers since 2006 was replenished by the 2023 storms.

“Taking a 3-D water storage in aquifers over time is quite exciting,” says Roland Bürgmann, a geophysicist at the University of California, Berkeley. Although the technique shows promises, many regions do not have large dense networks of seismic instruments that California does. But for those areas, researchers may be able to extract useful information from the underground fiber networks equipped with the right sensors.