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Tonga volcano eruption


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The Big Bang that took a nation off the grid

The strong submarine Hunga-Tonga-Hunga-Ha'apai volcano eruption and the subsequent tsunami and shock waves were felt across the Pacific Ocean and beyond.

This “Big Bang” released mechanical energy equivalent to hundreds of Hiroshima nuclear explosions, creating supersonic air pressure waves that were observed from space.

Key Numbers


of Tonga's population affected (approx. 85,000 people)


as powerful as the atomic bomb dropped on Hiroshima

90.4 million

USD in damages


of Tonga's GDP compromised

In the Kingdom of Tonga, the volcanic ash, tsunami and shock waves caused widespread devastation in several islands, and, in particular, destroyed the only fibre-optic cable that connects the islands with the rest of the world, leaving the country offline for more than three weeks. Four months later, communication between islands was still not fully restored. Disruption of Internet connectivity with Tonga had serious implications on its economy: about 30 per cent of household consumption and 40 per cent of national GDP in Tonga depend on remittances from international migrants sent via the Internet. The disruption particularly affected women, who are highly dependent on remittances and have to deal with the increases in water and food prices during the emergency.

Like Tonga, many other islands rely on a single cable, increasing their vulnerability not just to volcanic eruptions or tsunamis but also to more frequent disturbances, such as damage from fishing boats.

Additionally, the relief and recovery efforts of the Tongan government and emergency services were hampered by the inability to communicate. Access to satellite connectivity is limited, and even with it, communications failed due to the volcanic ash. Undersea fibre optic cables are crucial for the communication of the Pacific Islands with the rest of the world.

Like Tonga, many other islands rely on a single cable, increasing their vulnerability not just to volcanic eruptions or tsunamis but also to more frequent disturbances, such as damage from fishing boats. While adding an additional cable seems an easy solution, countries face many challenges, starting with the high financial investment needed (e.g. the construction of the cable to Tonga cost $15 million in 2013) but also concerns related to foreign surveillance and ownership of data by the countries providing more cables.

Wider picture

In a world highly interconnected by communication and technology, the inability to “be online” becomes a vulnerability in the context of extreme events as the case of the Hunga-Tonga Hunga-Ha'apai volcano eruption showed. Many Pacific Island countries, such as Vanuatu and Samoa, also depend on a single submarine cable, and satellite services are restricted and not widespread enough to cover basic connectivity needs. Damage to critical telecommunication infrastructure not only hinders response actions but also minimizes the effectiveness of early warning systems, compromising disaster risk management strategies and triggering offline scenarios as in Tonga.

Root Causes

Unequal distribution of economic opportunities and limited livelihood options

A lack of perception, awareness or preparation in governance relating to risk management and response

Pursuit of economic or developmental interests with a lack of consideration for impacts on the environment


An absent or poorly communicated warning of a hazard’s impending arrival.

Intentional mass removal of trees, often for resource extraction or changing land use.

Infrastructure vulnerable to extreme events, often due to lack of investment, maintenance, inadequate planning or poor construction.


Through their impacts on natural and agricultural systems, supply chains and economies, disasters can put access to the foods we depend on for survival at risk.

Water security can be impacted by disasters when sufficient availability or access to water for health and livelihoods is disrupted. Water sources can also get contaminated and make vectors for other risks.

Disasters can force people to move from their homes due to the loss of shelter, livelihoods or the risk of further incidents occurring. People may be temporarily displaced or urged to migrate to other areas.

Disasters cause fatalities both when they occur and in the aftermath with cascading effects on physical and mental health.

Public and private structures and systems can be impacted by disasters, from homes and properties to physical assets critical for providing health services, transport, food, water, communications and more.

Even those surviving disasters when they occur can be at risk of short- and long-term health impacts cascading from pollution or damage of critical infrastructure and livelihood disruption.

Just like people, nature also feels the impacts of various hazards resulting in threats to health and physical damage to individuals, populations, communities or entire ecosystems.

Reduction of people’s ability to support themselves or their family, both temporarily or permanently, is an impact that is interconnected with many others, including health and food security.


Ecosystem restoration: Coastal ecosystem restoration, especially involving robust, native species, can build protective “green belts” along vulnerable coastlines to protect from storm surge. Used sustainably in combination with traditional sea walls or dykes, such green belts can help to increase carbon sequestration and biodiversity while also continuously adapting to climate change impacts.

Social protection: Programmes to foster the capacity of people to respond to hazards when they strike are critical for reducing risk for vulnerable (e.g. female-headed households) or marginalized groups (e.g. people on remote islands). Accessible financial support, such as social protection, climate risk insurance or credit, can help in areas with limited livelihood opportunities to build resilience.

Diversify infrastructure: As critical infrastructure is also susceptible to the impacts of hazards, diversification of systems allows for redundancy, which can be an important factor in reducing risk. In places like Tonga, where the reliance on a single undersea cable led to cascading impacts, expanding satellite services can be part of the solution. However, issues of cost and geopolitical considerations need to be addressed.

Satellite monitoring: Obtaining early warning signals through improved observation technologies and education to prepare people to act effectively translates into saving lives and reducing related damage. In Tonga, the tsunami alert system was effective; however, improving collaboration across sectors and institutions can enhance technology for detecting different kinds of eruptions and warn other countries that could be impacted in a timely manner.