The phrase "activity ceased" is correct and usable in written English.
It can be used to indicate that a particular action or process has stopped or come to an end.
Example: "Due to unforeseen circumstances, all activity ceased until further notice."
Alternatives: "activity stopped" or "activity halted".
That had led to an expectation among a number of media buyers that sales of the i would take a hit as the promotional activity ceased.
An estimated 160,000 households went dark, hospitals turned to emergency generators and much commercial activity ceased.
The settlements were abandoned; the Indians were absorbed by either the landed estates or the jungle; the settlements fell into ruin; and economic activity ceased.
The Moon presently has very slight seismic activity and little heat flow from the interior, indications that most internal activity ceased long ago.
All literary activity ceased in the 16th century because of the unsettled conditions that prevailed before and after the annexation of the country by the Burmese.
For the first time in the middle ages, fighting – that quintessential lay aristocratic activity – ceased to be a sinful necessity in a fallen world, and became instead an expression of devoted and meritorious service to Christ as lord.
At some point, quasar activity ceases completely, leaving behind the dormant massive black holes found in most massive galaxies.
Examples include limited-scope photo sharing groups whose activity ceases shortly after the photos are uploaded and consumed by small social circles.
This activity ceases soon after the exposure of the cell to the external agent.
The cortically driven regulatory activity ceases when descending pathways are interrupted by the injury, thus giving rise to enhanced activity of spinal segmental reflexes under the injury level.
In T. cruzi at least, expression is known to be stage-specific, with activity ceasing in bloodstream-form, non-replicating trypomastigotes [ 17].
