🏙️ Immediate to Short-Term (Days to Centuries)

• Hours to weeks: Power grids fail; nuclear reactors melt down without maintenance[11].
• Months to decades: Urban areas flood as drainage systems fail; buildings decay from weather and plant growth[6][11].
• 100–300 years: Steel structures collapse; concrete buildings crumble[5][7]. Most cities become overgrown forests[6].

Medium-Term (Thousands of Years)

• 1,000 years: Visible surface structures (e.g., roads, monuments) are buried or eroded. Plastics fragment but persist chemically[5][7].
• 10,000–250,000 years: Nuclear isotopes (e.g., plutonium-239) remain detectable in sediments and ice cores[7]. Mining tunnels fill with sediment but leave identifiable “industrial fossils”[7].
• 500,000 years: Microplastics and polymer layers in ocean sediments endure[5][10].

Long-Term (Millions of Years)

• 1–7 million years: Fossils of humans and domesticated animals persist. Geological strata show elevated carbon levels and mass extinction markers[4][8]. Deep mines and landfills remain as distinct layers[7][10].
• 50–100 million years: Continental drift subducts surface evidence; satellites decay or drift into space[3][10]. Only deep geological traces (e.g., mine shafts, isotope ratios) might endure[3][10].
• 250 million years: Next predicted mass extinction eradicates all mammals, including any remaining human traces[9].

Near-Permanent Traces

• Space artifacts: Lunar landers, Mars rovers, and Voyager probes persist for billions of years[3][10].
• Radio signals: Human broadcasts travel through space indefinitely at light speed[5].

Key Factors

• Detection likelihood: Aliens or future species could find traces for 100+ million years via deep geological analysis or space exploration[5][10].
• Total erasure: Requires Earth’s destruction (e.g., solar expansion in 5 billion years)[10].

Citations: [1] Human extinction https://en.wikipedia.org/wiki/Human_extinction [2] What If Humans Suddenly Went Extinct? https://www.youtube.com/watch?v=yuOKTZISXhc [3] How long would it take for all traces of humans to be gone? https://www.reddit.com/r/answers/comments/1azu120/how_long_would_it_take_for_all_traces_of_humans/ [4] What would happen to Earth if humans went extinct? https://www.livescience.com/earth-without-people.html [5] How long before all human traces are wiped out? https://www.newscientist.com/lastword/2215950-how-long-before-all-human-traces-are-wiped-out/ [6] Vanishing Act: What Earth Will Look Like 100 Years After Humans Disappear - Brilliantio https://brilliantio.com/if-people-dissapeared-what-will-happen-to-earth-in-100-years/ [7] If humans became extinct, how long would it take for all … https://www.sciencefocus.com/science/if-humans-became-extinct-how-long-would-it-take-for-all-traces-of-us-to-vanish [8] Nature will need up to five million years to fill the gaps caused by man-made mass extinctions, study finds https://www.independent.co.uk/climate-change/news/mass-extinctions-five-million-years-nature-mammals-crisis-animal-plants-pnas-aarhus-a8585066.html [9] Humans Will Go Extinct on Earth in 250 Million Years; Mass Extinction Will Occur Sooner if Burning Fossil Fuels Continues [Study] https://www.sciencetimes.com/articles/49951/20240430/humans-will-go-extinct-earth-250-million-years-mass-extinction.htm [10] How long would it take for all evidence of humanity to be … https://worldbuilding.stackexchange.com/questions/153618/how-long-would-it-take-for-all-evidence-of-humanity-to-be-erased-from-earth [11] What Would Happen If Every Human On Earth Just Disappeared? https://www.scienceabc.com/humans/life-like-humans-suddenly-disappeared.html