As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 70 - PHX-SEA - CREW REPORTED AFTER LEVELING OFF AT FL340, RECEIVED A "CABIN ALTITUDE WARNING HORN" FOLLOWED BY A RISE IN CABIN PRESSURE ALTITUDE. CREW DESCENDED TO FL 200 AND DECLARED AN EMERGENCY. CREW DIVERTED TO LAS. CABIN WAS NOT PREPPED. THE LANDING WAS UNEVENTFUL. MX DISCOVERED AFT CARGO DOOR SEAL TORN. MX REPLACED SEAL. PRESSURIZATION CHECK WAS GOOD. AIRCRAFT WAS RETURNED TO SERVICE.