Add-PSSnapin microsoft.sharepoint.powershell 
$names = "Alerts"
foreach ($name in $names)
{
  Get-SPLogLevel -Identity $name
  set-sploglevel -Identity $name  -TraceSeverity verbose -EventSeverity verbose #default value Tracesev High and EventSev Information    
}
write-output "Trace levels set to verbose for"
$names |format-table -AutoSize