After playing around some more I figured it out.
long EventUnixTime = eventData.getEventUnixtimeTime();
long EventUnixTimeMilli = (EventUnixTime *1000);
Date EventDate= new Date(EruptionUnixTimeMilli);
SimpleDateFormat EventDateFormatter = new SimpleDateFormat("yyyy-MM-dd");
EventDateFormatter.setTimeZone(TimeZone.getTimeZone("US/Mountain"));
SimpleDateFormat EventTimeFormatter = new SimpleDateFormat("HHMM");
EventTimeFormatter.setTimeZone(TimeZone.getTimeZone("US/Mountain"));
String EventRegDate = EventDateFormatter.format(EventDate);
String EventRegTime = EventTimeFormatter.format(EventDate);
This outputs two strings one that is YYYY-MM-DD and one that is HHMM always in Mountain Time.