21 male and female teenage participants will be randomized to one of three varying baseline assessment periods of two, four, or six weeks. Multiple baseline is a type of single-case experimental design (SCED) that is a time- and cost-effective method for evaluating efficacy of a new treatment, Sonoma Rises. The randomization of participants to baseline periods of varying lengths enables assessment of whether symptom changes occur when, and only when, the intervention is applied.

All participants will receive the intervention, Sonoma Rises, a mobile app designed by psychologists at the National Center for PTSD for wildfire survivors to facilitate recovery from disaster. Users can access evidence-informed tools to help cope with stress, heal from loss, prioritize self-care, connect with others, manage anger, and track their mood using validated assessments. There are also tools designed just for teens and users are linked to psychoeducation on disaster and health and other mental health resources and services.

retention (i.e., number of treatment completers)

safety (i.e., number of adverse events)

adherence rates (i.e., number of treatment components completed)

satisfaction/acceptability (i.e., participant satisfaction with treatment "how would you rate your overall satisfaction with the program?"- range 0-10 - higher score indicates more satisfaction)

Net promoter score (i.e., "How likely are you to recommend this to a friend?" score range 0-5; lower score indicates higher likelihood of promotion)

Engagement rate (i.e., Number and average length of logins to the mobile app intervention)

Child PTSD Symptom Scale for Diagnostic and Statistical Manual-5; score ranges from 0-80; higher scores indicate more PTSD symptom severity

Behavior and Feelings Survey - Youth; range 0-24; higher scores indicate more internalizing symptoms (anxiety, depression, stress)

Behavior and Feelings Survey- Youth; range 0-24; higher scores indicate more externalizing symptoms (behavior problems)