警報

1. Origins, structure, and basic meaning

• Structure: 警報 is read as けいほう and is a noun for an alarm or warning issued or sounded to announce danger and prompt action.
• Basic usage: An official alert appears in 警報が出る, while an alarm device sounding appears in 工場で警報が鳴る.

2. Common pitfalls and similar expressions

• Issuance and activation
  • 警報が出る suits an official weather or disaster alert, while 警報が鳴る describes an alarm device sounding.
• Difference from 警告
  • 警告 broadly covers the act or content of warning someone, while 警報 readily denotes an official danger alert or a signal from an alarm system.