Satellite-based emergency alert systems:  pros, cons, and the  road to readiness

Effective disaster relief hinges on the ability to communicate swiftly and accurately with affected populations. GNSS-based emergency alert systems, such as Galileo Emergency Warning Satellite Services (EWSS) in the European Union, J-Alert in Japan, or The Emergency Alert System (EAS) in the US, offer unique benefits. Tests in regions that are prone to natural disasters - earthquakes, tsunamis, cyclones… - have proved that the emergency management command system based on GNSS can play the role of "lifeline" in a critical moment. However, due to the inherent limitations of EWSS, adopting a multichannel approach that integrates satellite technology with other communication methods is essential. 

Why satellites are critical in crisis situations 

GNSS-based emergency alert systems are highly efficient and powerful in scenarios requiring rapid, large-scale communication, especially in situations where traditional networks are compromised, when infrastructure fail, or during cross-border emergencies. GNSS technology offers high reliability and outdoor positioning accuracy, even in regions with low cellular density, ensuring geographically precise alerts with accuracy up to 1 meter. This precision enables the targeting of specific areas for danger or vigilance. 

In the aftermath of an earthquake, for instance, when ground-based communication networks might be damaged or overwhelmed, satellite alerts can still be broadcast to affected populations. These alerts can be deployed quickly, ensuring that critical information reaches those in need without delay. This ability to function independently of terrestrial infrastructure makes satellite systems a crucial tool in crisis management. 

Furthermore, the wide coverage provided by satellites extends to remote and rural areas that might otherwise be difficult to reach. In cross-border situations like a tsunami threat, a satellite system can geotarget notifications across multiple countries simultaneously, enhancing the relevance and effectiveness of the alerts and ensuring a coordinated response among nations. 

The ongoing journey to effective satellite alerts

While the potential of satellite-based emergency alert systems is clear, it has limitations: 

• One significant challenge is device compatibility: At present, only a small percentage of smartphones are equipped to receive satellite alerts. This limitation restricts the effectiveness of the system, as large portions of the population may be left out of critical communications.  
• Another issue is the system's dependency on outdoor environments. Satellite signals require a clear line of sight to the sky, meaning that GNSS does not function properly indoors. Find more explanations in this article. 
• Another limitation of GNSS-based emergency alert systems is their one-to-many dissemination model, which lacks contact management, meaning they can only alert all compatible devices in an area without the ability to target specific groups or lists. 

• The Galileo Early Warning Satellite Service is anticipated to become operational in 2025. Recent tests conducted with various national civil protection agencies have demonstrated that alert messages can be transmitted and received by all users within the danger zone in under 60 seconds.

   

Maximizing reach: Why multi-channel is key

Given the current limitations of satellite warning systems, it is essential to view them as one component of a broader emergency communication strategy. A multichannel approach that combines satellite alerts with traditional methods like SMS, social media, radio, and television will ensure more comprehensive coverage. 

For instance, in urban areas with strong mobile network coverage, location-based SMS alerts may reach targeted people quickly, especially indoors. At the same time, satellite alerts can provide a valuable backup, ensuring that messages get through even if the cellular network fails. This integrated approach also allows for more targeted and contextualized messages.  

By complementing and enhancing existing communication channels, satellite systems can play a crucial role in a multichannel emergency response strategy, increasing the chances that critical information reaches everyone who needs it, regardless of their location or the state of local infrastructure. 

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