Researchers at the Dholavira archaeological site in Gujarat have identified a unique circular pit structure that may have served as the world's earliest seismic warning system. The pit, dating back to the Mature Harappan period (2500 BCE), features a series of suspended heavy stone weights and a specialized sand-pavement floor designed to record vibrations from the earth.
The team suggests that the Indus Valley civilization, which lived in a highly tectonic region, developed these 'observation pits' to monitor tremors. By analyzing the patterns left by the weights in the fine sand, ancient residents may have been able to assess the frequency and intensity of local earthquakes, demonstrating an advanced understanding of geophysical phenomena nearly four millennia ago.