Methods and devices are disclosed for measuring low levels of acceleration caused by low frequency seismic waves. For example, an omnidirectional beam accelerometer configured to measure low frequency waves is disclosed. The omnidirectional beam accelerometer may include three beam acceleration sensors. Each beam acceleration sensor may include a respective mass and a respective beam. Each respective beam may be comprised at least in part of a piezoelectric material. Each beam acceleration sensor may have a ratio of mass density [kg/m3] to beam stiffness [N/m] of at least 4.5×10−5 kg/Nm2. The omnidirectional beam accelerometer may also include a housing to ensure the sensors are operating in orthogonal directions and an interface circuit to interface between the sensor and external circuitry.