According to the USGS, however, the seismic signature more closely resembled an explosion than a naturally occurring earthquake. Military shock trials are designed to simulate the kinds of underwater explosions a ship could encounter during wartime, including blasts from naval mines or torpedoes. While startling to nearby residents, the exercise is part of a long-established Navy process for validating the survivability of newly constructed warships. According to the Naval Sea Systems Command, Full Ship Shock Trials expose vessels to controlled underwater detonations to confirm they can continue operating under harsh combat conditions before joining the fleet. Although the explosion generated concern, Navy officials have historically said these types of tests are conducted under strict environmental guidelines.