Desencadenador de SQL Server 2005:¿cómo determinar de forma segura si se activa mediante ACTUALIZAR o ELIMINAR?

¿Por qué no creas dos disparadores separados?

CREATE TRIGGER [myUpdateTrigger] ON [myTable]
FOR UPDATE
AS
BEGIN

END

CREATE TRIGGER [myDeleteTrigger] ON [myTable]
FOR DELETE
AS
BEGIN

END