Question

where had tilly seen the sea behaving in the some strange fashion?​

Answer 1

Answer:

Tilly had seen the sea behaving in the same strange fashion in a video of a tsunami (shown in her geography class) which had hit the Hawaiian Islands in 1946.

Answer 2

: Required Answer

$\longrightarrow$ Tilly had seen the sea behaving in the same strange fashion during her geography lesson when her geography teacher had shown her class the video and told them that tsunamis can be caused by earthquakes, volcanoes and landslides.