their locations are located on nearby podiums at both ends of the Memorial. The memorial has had some unforeseen maintenance issues. In 1984, cracks were detected in the granite and, as a result, two of the panels were temporarily removed in 1986 for study. More cracks were later discovered in 2010. There are a number of hypotheses about the cause of the cracks, the most common being due to thermal cycling. In 1990, the Vietnam Veterans Memorial Fund purchased several blank panels to use in case any were ever damaged; these were placed into storage at Quantico Marine Base. Two of the blank panels were shattered by the 2011 Virginia earthquake. Names Inscribed on the Memorial are the names of service members who were classified as dead, missing, or prisoner. The list includes names of individuals who died due to circumstances other than killed in action, including murder, vehicle accidents, drowning, heart attack, animal attack, snake bites and others. The names are inscribed in Optima typeface, designed by Hermann Zapf. Information about rank, unit, or decorations is not provided on the Wall itself. Those who were confirmed as dead are denoted by a diamond shape next to the name, and those who are status unknown are denoted with a "cross" sign. When the death of one who was previously missing is confirmed, a diamond is superimposed over the cross. If a missing man were to return alive, which has never occurred to date, the cross is to be circumscribed by a circle. The earliest date of eligibility for a name to be included on the Memorial is November 1, 1955, which corresponds to when President Eisenhower deployed the Military Assistance Advisory Group to train the Army of the Republic of Vietnam. The last date of eligibility is May 15, 1975, which corresponds to the final day of the Mayaguez incident. The names are listed in chronological order, starting at the apex on panel 1E on July 8, 1959, moving day by day to the end of the eastern wall at panel 70E, which ended on May 25, 1968, starting again at panel 70W at the end of the western wall, completing the list for May 25, 1968, and returning to the apex at panel 1W in 1975. There are some deaths that predate July 8, 1959, including the death of Richard B. Fitzgibbon Jr. in 1956. There are circumstances that