Existing gravimeter tech: "City-size seamount triple the height of world's tallest building discovered via gravitational anomalies" (2024) https://www.livesci

Existing gravimeter tech: "City-size seamount triple the height of world's tallest building discovered via gravitational anomalies" (2024) https://www.livescience.com/planet-earth/rivers-oceans/city-size-seamount-triple-the-height-of-worlds-tallest-building-discovered-via-gravitational-anomalies https://www.livescience.com/planet-earth/rivers-oceans/city-... "Kerr-enhanced optical spring for next-generation gravitational wave detectors" (2024) , and/or Tantalum; https://news.ycombinator.com/item?id=39957123 https://news.ycombinator.com/item?id=39957123