At FL250 the aircraft flew into a normal looking cloud, which turned out to be a volcanic ash cloud (the result of an eruption of Mount Redoubt). Power was added to climb out of the cloud. About 10-15 seconds later all 4 engines failed and the standby electrical system failed. The crew were able to restart the engines after numerous attempts. The no. 1 and 2 engines were relit while descending through FL130 and the remaining 2 engines were relit at FL110. The aircraft landed safely at Anchorage, substantially damaged by the in-flight blasting by volcanic ash. The windshields were damaged, as were internal aircraft systems, avionics and electronics. PROBABLE CAUSE: “Inadvertent encounter with volcanic ash cloud, which resulted in damage from foreign material (foreign object) and subsequent compressor stalling of all engines. A factor related to the accident was: the lack of available information about the ash cloud to all personnel involved.”