Meadow Creek Park Emergency Planning and Information
A couple of links that may be of some interest.
The National Volcano Early Warning system (NVEWS) has a subscription page to receive alerts (https://volcanoes.usgs.gov/vhp/updates.html). This will be for all US volcanoes and the Hawaii and Alaska volcanoes are generally fairly active so most of the messages will be for those places.
The Pacific Tsunami warning center also has a subscription page to receive alerts (http://ptwc.weather.gov)
Pierce county emergency management (http://www.co.pierce.wa.us) has a few good examples of what different lahar warning siren sounds like. Not sure if other counties have something similar, I will still keep looking.