Sonos Play 1 as an alarm

Is it possible to use a Sonos Play 1 to sound an “alarm/siren sound” when a pre designated smartthings sensor is triggered ? If this can be achieved, can I pre select the volume at which the audible alarm would sound ?

Yes. Unfortunately the integration is very wonky. It only works about half of the time for me. You have to use the Sonos connect app and then use the notify with sound app in the smartapp marketplace

You can also use Rule Machine with Expert Features to accomplish this.

You can use the Sonos Mood Music app for this. I have something similar set-up with my Play:1 that should work for you in this situation. Mine is set to play a ‘Morning’ playlist when it detects motion in my bedroom after 7AM. You could just set it to play an alarm sound instead of a playlist. See the ‘Temporarily change volume’ setting under ‘More options’.