随即;随后;于是；Thereupon means happening immediately after something else has happened and usually as a result of it. [ADV with cl] [Formal]
Some months ago angry demonstrators mounted a noisy demonstration beneath his window. His neighbours thereupon insisted upon more security.
几个月前，愤怒的示威者在他的窗下发起了闹哄哄的抗议活动，随后他的邻居们坚决要求加强安全防范。