# A Hybrid Scheme for Disaster-Monitoring Applications in Wireless Sensor Networks
### Motivation  
Disaster monitoring is critical for environmental monitoring. To protect against and mitigate the damage caused by earthquake disasters, three tasks should be performed: earthquake prediction, emergency management of earthquake hazards, and recovery from earthquakes [6]. Earthquake prediction is a scientific challenge worldwide and is still in the research and exploration stages. Earthquake early warning (EEW) is a feasible strategy to mitigate the effects of seismic hazards [7]. The essential task is to save lives during the emergency management of earthquake hazards. When large earthquakes occur, buildings and facilities are destroyed, and communication is intermittent. Under these circumstances, if an early warning of a violent earthquake is not provided, severe damage can occur. By taking advantage of electromagnetic waves that spread faster than seismic waves, an early warning can be provided when an earthquake occurs. This may not only immediately stop high-speed trains, nuclear power stations, and electric elevators in high-rise buildings, but may also provide people with precious time of more than 10 s to save lives, especially the lives of those who are approximately 60 km from the epicenter [8]. The seismic station is the basic setting of seismic monitoring. Seismic stations use geophones to detect earthquakes. Geophones are an electromechanical conversion device used to convert the seismic waves transmitted to the ground into electrical signals. They are the key piece of equipment involved in field data collection by seismic stations [9]. WSNs are a noteworthy method for implementing EEW. WSNs act as part of disaster-monitoring systems, and they have a considerable advantage over other networks because they do not depend on any other infrastructure, such as NB-IoT and 5G wireless networks [10]. When a large earthquake occurs, mobile communication base stations and fiber-optic networks are simultaneously destroyed. In this situation, WSNs can help disaster-monitoring systems to keep working. However, wireless sensor networks must achieve real-time transmission to perform this task. A system for EEW is a vital aspect of disaster monitoring because it allows people to survive earthquakes. Normally, an onsite earthquake early warning system measures the peak displacement amplitude and predominant period of the P-wave for 3-4 s to avoid frequent false alarms. Therefore, alerts sent by seismic monitoring nodes must be transmitted within tens of milliseconds in a wireless sensor network [11]. However, a violent earthquake can severely damage buildings and facilities and interrupt transportation systems and communication networks [12]. Maintaining contact with people in the post-earthquake regions is difficult. When emergency rescue is performed, landslides, mudrock flows, and aftershocks can lead to further casualties and damage. To mitigate this, real-time and accurate seismic data must be obtained by deploying robust sensor nodes in disaster areas for uninterruptible monitoring. To transmit post-earthquake disaster data, a rapid reporting system based on wireless sensor networks is an efficient strategy. After an earthquake, the nodes of the wireless sensor networks can be dropped onto the disaster area using unmanned aerial vehicles. In particular, when current information networks are interrupted, we can send important, timely information by taking advantage of these nodes. It is paramount that seismic monitoring nodes can transmit epicenter vibration information so that aftershock alerts from the seismic monitoring nodes in the system can be transmitted quickly. Moreover, the goal is to obtain information about earthquake areas, and multimedia information about disaster situations is extremely important [13]. In another disaster-monitoring scenario, volcanic research and monitoring are vital for responding to volcanic eruption disasters [14].