A single-compartment combined-sphere broad-frequency
submarine seismometer, which comprises a submersion
coupling frame, a
seismometer compartment, a function compartment and an unhooking mechanism. The submersion
coupling frame, which is located at the bottom of the
submarine seismometer, is provided with a rigid ring to accommodate the seismometer compartment and thereby allow the sealed seismometer compartment (48) inside said seismometer compartment to sit on the
seabed directly. The seismometer compartment comprises a bell-shaped protective cover (49) and the sealed seismometer compartment (48). The bell-shaped protective cover (49) opens downwards. The upside of the sealed seismometer compartment (48) is suspended from the top inner surface of the bell-shaped protective cover (49) by multiple cables, and the underside of the sealed seismometer compartment (48) extends beneath the opening of the bell-shaped protective cover (49) to sit flush with the underside of the submersion-
coupling frame. The unhooking mechanism is provided on the function compartment (36) and is connected fixedly with the rim of the submersion-coupling frame by a fusible tension steel wire (24), thus fixing the function compartment (36) and the seismometer compartment to the rigid ring at the center of the submersion coupling frame. The seismograph is installed in the sealed seismometer compartment (48) and is thus seated on the
seabed directly, whereby the severe
distortion of horizontal signals recorded by the
submarine seismograph can be effectively overcome without the use of multilayer coupling structures.