What was found
AT CRUISE FELT MODERATE VIBRATION IN AIRFRAME FOLLOWED BY UNCOMMANED DEPRESSUIZATION. FOLLOWED QRC & QRH, NEITHER HAD ANY EFFECT. AT APPROX FL240-200 GOT CABIN ALT CAUTION FOLLOWED BY WARNING. DECLARED EMERGENCY AND DEVIRTED. UPON ARRIVAL AT GATE FOUND MCD DOOR SEAL TORN FROM SEAL TRACK. (FLIGHT 5301) AT CRUISE FELT MODERATE VIBRATION IN AIRFRAME FOLLOWED BY UNCOMMANED DEPRESSUIZATION. FOLLOWED QRC & QRH, NEITHER HAD ANY EFFECT. AT APPROX FL240-200 GOT CABIN ALT CAUTION FOLLOWED BY WARNING. DECLARED EMERGENCY AND DEVIRTED. UPON ARRIVAL AT GATE FOUND MCD DOOR SEAL TORN FROM SEAL TRACK.