You don't provide enough information. Depending on what sort of eventlog you are dealing with can make a difference. Most eventlogs take care of themselves and should never be deleted. Also, most eventlogs are in constant use and so GetFileTime() will not work. Here is a script to demonstrate that.
code:
Break on
$BasePath = "%windir%\system32\config\"
$strFile = "appevent.evt","secevent.evt","sysevent.evt"
For each $element in $strFile
	GetAllFileProperties($BasePath+$element) 
Next
get $_

For each $element in $strFile
  ? $BasePath + $element + " size = "
  GetFileSize($BasePath + $element) 
  ? $BasePath + $element + " time = "
  GetFileTime($BasePath + $element) 
Next
get $_

Function GetAllFileProperties($FileName) 
	$fso = CreateObject("Scripting.FileSystemObject") 
	$objFile = $fso.GetFile($FileName) 
	? "Date created: " + $objFile.DateCreated 
	? "Date last accessed: " + $objFile.DateLastAccessed 
	? "Date last modified: " + $objFile.DateLastModified 
	? "Drive: " + $objFile.Drive 
	? "Name: " + $objFile.Name 
	? "Parent folder: " + $objFile.ParentFolder 
	? "Path: " + $objFile.Path 
	? "Short name: " + $objFile.ShortName 
	? "Short path: " + $objFile.ShortPath 
	? "Size: " + $objFile.Size 
	? "Type: " + $objFile.Type 
EndFunction
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