A Qantas Airbus A380-800, registration VH-OQK performing flight QF-94 from Los Angeles,CA (USA) to Melbourne,VI (Australia), was enroute at FL310 over the Pacific Ocean about 2 hours into the flight when the aircraft encountered turbulence causing it to descend for about 10 seconds before the crew recovered the aircraft and returned it to the assigned flight level. The aircraft climbed to FL320 shortly afterwards and continued to Melbourne for a safe landing without further incident. A Qantas Airbus A380-800, registration VH-OQF performing flight QF-12 from Los Angeles,CA (USA) to Sydney,NS (Australia), was enroute at FL320 over the Pacific Ocean about 2 hours into the flight, the aircraft had departed Los Angeles about 75 seconds prior to QF-94. The aircraft initiated a step climb to FL340 at or shortly after the occurrence. The occurrence became known by passenger reports indicating that they had perceived a sudden loss of weight and were holding hands when their aircraft nose dived for about 10 seconds. The captain announced that they had experienced wake turbulence from another Qantas A380, they were now talking to ATC and were about to change their flight path slightly. Based on the passenger reports Australia's TSB have asked Qantas for an explanation. A current theory is flight QF-94 encountered wake turbulence from flight QF-12. On Jun 14th 2018 Qantas' chief pilot explained the trailing aircraft QF-94 encountered some wake turbulence from the leading aircraft QF-12 20nm ahead and 1000 feet above, the wake turbulence caused a jolt to the aircraft for a short period of time with pitch variations of up to 3 degrees. The aircraft climbed maybe 100 feet and descended back to its cruising altitude, the captain took action to avoid further exposure to the wake vortex. There were no injuries and no damage. The occurrence has been reported to the ATSB and the aircraft manufacturer. The ATSB reported occurrences affecting the safety of the aircraft need to be reported to the ATSB. Based on the facts of this occurrence there was no requirement to notify the ATSB immediately. The operator notified the ATSB within 72 hours, the information was reviewed and no safety investigation was opened.