Which outcome occurred in Roman sieges when attackers tunneled under city walls lacking bedrock foundations?

💡 Explanation

When tunnels were dug under walls without bedrock, soil compaction occurred because the walls' weight exceeded the soil's bearing capacity, leading to ground subsidence and ultimately wall collapse. Therefore, wall subsidence results, rather than groundwater flooding, poison gas build-up or spontaneous combustion, which require different geological conditions or mine tactics.

• Which critical risk increased when 18th-century ships began using iron ballast near navigation equipment?
• Which constraint limited the casting size of early Mesopotamian bronze tools and weapons?
• Which limitation increased significantly when constructing wooden-hulled ships exceeding around 300 tons in the 18th century?
• Which optical phenomenon explains how Ibn al-Haytham demonstrated light travels in straight lines using a camera obscura?
• Which outcome occurred when ancient Mesopotamian bronze metalworking reached temperatures above 1085°C in crucible furnaces?
• Within Aztec chinampa agriculture, which mechanism limits sustained yields during prolonged drought conditions?