The ability to provide a stable and durable energy supply for sensing nodes in a wireless sensors network (WSN) is an important research issue for WSNs in structural health monitoring (SHM) systems. Furthermore, a common approach to reduce energy consumption of sensors in a WSN is having control sensors periodically enter a low-power mode or sleep state. This, however, is challenging to implement in large-scale WSNs due to the need for faultless time synchronization. In practice, the sampling process will be delayed if a sensor node receives a sampling command but the node remains in listening-time cycle. Hence, the capabilities of external-radio triggering can improve stability and durability when integrated with a peripheral low-power circuit attached to sensing nodes. If sensors are in a low-power mode or sleep state, an effective approach is to transmit a wake-up command when specific start-up conditions are met to quickly awaken sensing nodes and work wirelessly. The aim of this work is to develop an efficient energy management scheme for a WSN-based SHM system by integrating an on-site earthquake early warning system and wake-on radio. A coordinator is integrated with WSN gateways and employed to link and synchronize all sensing nodes in advance through seismic prediction and radio-triggering technology. The simulation results reveal that the average power consumed was measured at about 350 µA for sensing nodes. Such a sensor will be more effective in measuring structural responses after an earthquake by increasing available sleep time, thereby saving energy and extending the life of such a wireless sensing system.