USS Gridley (DLG-21) the "Spruance"-class destroyer to escort reflagged Kuwaiti oil tankers through the Strait of Hormuz during Operation Earnest Will. While homeward bound, transiting the South China Sea, "Gridley" rescued Vietnamese refugees sighted in a small boat off of the coast of Vietnam. A Vietnamese-speaking crewman aboard "Gridley" was able to translate for those rescued, facilitating the process. "Gridley" returned to San Diego in June 1989. On 17 October of that year, the ship's visit to Naval Station, Treasure Island, California, was interrupted by the 6.9 Loma Prieta earthquake that struck the San Francisco Bay area. "Gridley"s crew provided assistance to victims
1989 Loma Prieta earthquake by the WGCEP in 1988 was coincidental. The contrasting characteristics of the 1906 and 1989 events were examined by seismologists Hiroo Kanamori and Kenji Satake. The significant amount of vertical displacement in 1989 was a key aspect to consider because a long-term sequence of 1989-type events (with an 80–100-year recurrence interval) normally result in regions with high topographic relief, which is not seen in the Santa Cruz Mountains. Three scenarios were presented that might explain this disparity. The first is that the geometry of the San Andreas Fault goes through a transition every several thousand years. Secondly, slip type could