伊豆(いず) is a former province of japan that's now part of 静岡(しずおか)prefecture. I'm not sure where you'd repeatedly stumble across such a word outside of history books, although I'm familiar with the name somehow (I had to look up the facts).
Tiduas, there is a Japanese game called スーパーロボット大戦シリーズ (Super Robot Wars). In the game, the place '伊豆基地' is an army base. I'm not sure if this is what you've been seeing, but there is no real place with this name in Izu.