| Lake Biwa originated as a tectonic lake (Lake Oyamada); it formed approximately four to six million years ago around the present-day Hirata in Iga City, Mie Prefecture, as the result of tectonic movement. |
琵琶湖が形成された時期は、約400万年～600万年前で、現在の三重県伊賀市平田に地殻変動によってできた構造湖であった（大山田湖）。 |