This is the 9965th most frequent Japanese word.
起こ
"起こ" is a stem form meaning "to wake" or "to occur."
The verb '起こった' here depicts the event of an earthquake happening, representing the use of '起こ' to mean 'occur.'
地震が起こった。
An earthquake occurred.
Here '事件を起こした' implies causing an incident, using '起こ' to convey the idea of instigating or initiating an event.
気を散らしてはいけない事件を起こした。
You caused an incident that should not have been distracted.
In '議論を起こした,' the word '起こ' is employed to signify instigating or sparking a discussion.