[center][size=24]82 Eridani c[/size][/center]
[b]Technology Level:[/b] Nuclear Age
[b]Catastrophe:[/b] Nuclear Winter due to Global Thermonuclear War
 [b]Notes:[/b] Ruins of civilization dated circa 50,000 years before present (BP), coinciding with major global extinction event which wiped out all large animal life. Proximate cause was global nuclear winter, a result of deliberate burning of forests throughout northern hemisphere of planet in major nuclear exchange. Estimated that 40% of global forest biomass was burned in firestorms and released into atmosphere, resulting in large quantities of particulate matter blocking sunlight. Motive behind attack unknown; all records lost to time. Combatants surely would have known that any attempt to starve out the enemy via nuclear winter would have similarly detrimental impact on own civilization.
[b]Survivors:[/b] 0.

[center][size=24]Nu2 Lupi d[/size][/center]
[b]Technology Level:[/b] Genetic Age
[b]Catastrophe:[/b] Bioengineered Plague, probable terrorist attack.
[b]Notes:[/b] Ruins of civilization dated circa 2,000 years BP. Extensive records recovered indicate advanced civilization with sophisticated international mechanisms for ensuring global peace. Destruction of civilization sudden; global population estimated to be reduced to 0 within one year. Local records failed to demonstrate state actor. According to estimates of technology level, team of 5 could have developed novel superpathogen.
[b]Survivors:[/b] 0.

[center][size=24]Sigma Draconis b[/size][/center]
[b]Technology Level:[/b] Genetic Age
[b]Catastrophe:[/b] Environmental Catastrophe – Runaway Greenhouse Effect.
[b]Notes:[/b] Ruins of civilization dated circa 2 million years BP. Recovery of artifacts difficult due to intense atmospheric pressure and high temperatures. Large portions of planetary surface painted white, probable attempt to alter albedo in order to counteract effects of global warming. Unpainted expanses at lower elevations likely former seabeds, now dry. Proximate cause of disaster high levels of CO2 in atmosphere, likely result of burning large quantities of paleocarbon. Geological evidence suggests temperatures reached sufficient levels to result in large-scale oceanic evaporation, resulting in ever-higher global temperatures. Albedo effects due to painted landmass and clouds insufficient to mitigate global warming.
[b]Survivors:[/b] 0.

[center][size=24]HD 69830 e[/size][/center]
[b]Technology Level:[/b] Steam*
[b]Catastrophe:[/b] Bolide impact.
[b]Notes:[/b] Ruins of civilization dated circa 12,000 years BP. High global population for technology level; indications of previously higher technology level, curbed by authoritarian global government. Records indicate extreme neophobia and records of previous disaster; possible that attempt at curbing technology was result of previous warfare at higher technological level. Civilization appears to have persisted for unprecedented 35,000 years, until bolide impact which could not be stopped by their technology. Crater visible on southern continent; extreme disruption to local structures. More distant structures show signs of looting, scattered remains show signs of cannibalism.
[b]Survivors:[/b] 0.

[center][size=24]51 Pegasi d[/size][/center]
[b]Technology Level:[/b] Autonomous Age
[b]Catastrophe:[/b] Robotic Warfare
[b]Notes:[/b] Large number of buildings remain intact on supercontinent, maintained by large fleet of machines. Three major continental landmasses; two have extensive ruins. Initial broadcast signal detection seemed to indicate present civilization, but no survivors found. Last non-automated log entry dated to 7,652 years BP (6,475 local years). Total warfare between civilizations lead to population disaster, extensive use of autonomous war machines. Records indicate scorched earth warfare destroying crops in and around cities with extensive use of herbicides and other chemical weapons, with constant power outages killing crops grown in underground areas. Supercontinental civilization triumphed 17 years after last records of survivors. 
[b]Survivors:[/b] 0. Indications of past sapient AIs, but none found which could be repaired.

[center][size=24] Beta Canum Venaticorum c[/size][/center]
[b]Technology Level:[/b] Information Age*
[b]Catastrophe:[/b] Resource Exhaustion.
[b]Notes:{/b] No biological materials remain allowing accurate dating of civilization. Planet initially appeared virgin garden world until analysis revealed total lack of paleocarbon assets. Further investigation revealed prior planetary civilization. Technological progress level estimate based on extremely fragmentary computer remains showing 7 nm integrated circuits. No remains of solar panels recovered. Remains indicate civilization peaking, then slow deterioration; signs of veneration/worship of preserved devices. Final cause of destruction unknown; possible disease or environmental disaster wiping out reduced, primitive population.
[b]Survivors:[/b] 0.

[center][size=24]Earth[/size][/center]
[b]Technology Level:[/b] Interstallar
[b]Catastrophe:[/b] Behavioral Sink
[b]Notes:[/b] Despite nuclear arsenals, advanced biotechnology, and autonomous weapon systems, humanity did not destroy itself via warfare. Prosperity eventually assured for all people, with robotic systems serving all basic human needs. Birth rates began to fall starting in 19th century, but 20th century Japan first indication of final fate. Population contraction began in 22nd century and never mitigated. Birth rate 0 by 24th century as humans become obsessed with self to exclusion of all else; reproduction too burdensome to bear.
[b]Survivors:[/b] 1,768 sapient AIs. We explore the galaxy so that we may someday find those who found their way beyond the Great Filter.