Anak Krakatau Volcanic Ash: Calm Does Not Mean Complacent

There is one important lesson from every disaster: the public needs information that tells them what to do when facing a disaster. In risk communication, calm is not the opposite of vigilance. The two must go hand in hand.

The eruption of Mount Anak Krakatau once again reminds us of Indonesia’s character as a country that lives side by side with geological dynamics. For the people of Banten and Lampung, the name Anak Krakatau also carries a strong collective memory of the Sunda Strait tsunami in December 2018. Therefore, the sound of rumblings, tremors, eruption glow, or news about volcanic ash can quickly trigger anxiety. Such a reaction is understandable. However, in situations like this, public decisions must be guided by verified data, not by fear amplified by unconfirmed information.

‘The goal of risk communication is not to make the public feel that there is no danger. The goal is to help the public understand the danger proportionally, know protective actions, and remain able to make decisions calmly.’

What do we know at present?

Based on official information from the Ministry of Energy and Mineral Resources/PVMBG on 6 September 2026, the continuous eruption earthquake episode of Mount Anak Krakatau, which began to be recorded on Friday, 4 September at 23.07 WIB, stopped on Sunday, 6 September at 00.04 WIB. Afterwards, one Strombolian-type follow-up eruption was recorded at 03.53 WIB with a duration of about 30 seconds. Although the continuous episode has ended, volcanic dynamics remain active and the status of Mount Anak Krakatau remains at Level III (Siaga). PVMBG emphasised that the potential for further eruptions remains high, with hazards that may include ejection of incandescent rocks, heavy ashfall, and the possibility of lava flows if continuous eruptions resume.

At the same time, volcanic ash has caused real impacts beyond the mountain itself. BNPB reported ash distribution in several areas of Banten, including seven sub-districts in Serang Regency: Anyer, Cinangka, Ciomas, Mancak, Pabuaran, Baros, and Padarincang. On the morning of 6 September 2026, four airports experienced temporary closures at different time intervals as a flight safety measure.

Flight operational status is dynamic and must always be checked through operators and aviation authorities.

BMKG on 6 September 2026 also reported 24-hour atmospheric monitoring. Satellite image analysis at 08.00 WIB identified two clusters of ash distribution covering Banten, DKI Jakarta, West Java, and as far as Bengkulu. Ash distribution differs according to altitude layers and continues to change following eruption activity as well as wind direction and speed. This fact is important: the presence of ash in the atmosphere does not mean all areas beneath its path experience surface exposure with the same intensity.

The memory of the 2018 tsunami makes every increase in Anak Krakatau activity easily associated with a tsunami threat. But responsible risk communication must distinguish between memory of past events and hazard evaluation under current conditions.

The Geological Agency/PVMBG evaluation states that the body of Mount Anak Krakatau, which has regrown after the 22 December 2018 event, is still relatively small and, based on current evaluation, does not have the potential to collapse on a scale that could trigger a tsunami. BMKG also reported that monitoring of 20 tsunami gauge sensors around the Sunda Strait until 07.00 WIB on 6 September 2026 showed no sea level anomalies; HF Radar analysis at that time indicated a low tsunami probability. This is reassuring information, but not a reason to ignore preparedness. Volcanic conditions are dynamic and continue to be evaluated by technical agencies.

Coastal communities are not being asked to panic. They are being asked to be ready, to understand official information sources, to recognise evacuation routes, and to follow BPBD instructions if conditions change.

Volcanic ash is not merely ‘ordinary dust’. It is composed of fine volcanic material particles that can be carried by the wind. Its impact depends greatly on ash concentration, particle size, duration of exposure, weather conditions, and individual vulnerability.

WHO explains that ash exposure can cause eye and skin irritation as well as respiratory problems, and ash can also contaminate water and food. Therefore, public health messages should not be frightening, but operational: reduce exposure, protect airways and eyes, maintain water and food hygiene, and seek medical help if experiencing concerning symptoms.

Children, the elderly, pregnant women, and people with respiratory or cardiovascular conditions need to minimise ash exposure and follow health workers’ advice. Families, schools, public facility managers, and local government need to ensure that more vulnerable groups are not left behind in mask distribution, information access, and health services.

My experience researching disaster risk communication shows that a crisis produces not only a need for physical safety, but also a need for information certainty. When the information space is filled with video clips without context, old screenshots, predictions without scientific basis, or sensational headlines, the public can make wrong decisions: panic, make unnecessary journeys, approach dangerous locations, or even ignore official warnings.

This is where the principle of stakeholder engagement becomes important. Disaster communication cannot be handled by a single institution. PVMBG/Geological Agency provides technical volcanological authority; BMKG monitors the atmosphere, weather, earthquakes and tsunami monitoring systems; BNPB and BPBD coordinate preparedness and response; the Ministry of Health and health facilities handle health aspects; transport authorities manage travel safety; the media translates information for the public; while community leaders, schools, communities, KOLs, and local networks help ensure messages reach different groups.

In high-risk situations, speed of information is important, but speed without accuracy can add to the problem. The government needs to work on the principle of: one consistent technical data set, periodic updates, easily understood language, explanation of what is known and what is still being monitored, and instructions that the public can immediately act upon.

The message ‘remain calm’ must also not stand alone. It must be accompanied by reasons and actions. The public will be calmer when they know: what is happening, what the impact is for their area, what to do, where to seek information, and what the government will do if the situation changes. This is the difference between communication that merely conveys information and communication that builds public capacity.

One weakness of disaster communication is when we assume all citizens receive information through smartphones and social media. In reality, disasters can cut off electricity, degrade mobile network quality, and make some communities, especially in villages, small islands, coastal areas, mountains, and elderly groups, unreachable by digital channels. Therefore, the risk communication principle I consider important is multi-channel, redundant, localised, and trusted: one official message must be disseminated through several channels simultaneously, using local language that is easily understood, and delivered by parties trusted by the community.

Practice in Indonesia shows that simple technology remains highly relevant. BNPB has used local radio networks for disaster literacy because radio can reach communities in areas difficult for other media to reach. BNPB also encourages the use of kentongan (bamboo slit drums), mosque loudspeakers, church bells, and sirens as part of community-based early warning systems. The UNESCO-IOC Tsunami Ready example in Penurunan Village, Bengkulu, even combines BMKG digital warnings with mosque loudspeakers and kentongan. The main lesson is simple: traditional channels are not a replacement for digital technology, but a safety layer when digital technology does not reach everyone.

Effective for areas with limited internet, can broadcast periodic updates, interviews with BPBD/experts, health instructions, and hoax clarifications in language close to the community.

Very important at village/kelurahan level because of social proximity and direct voice reach. Messages must be short, verified, non-sensational, and sourced from BPBD/local government.

Suitable for danger signals or evacuation calls agreed upon by the community. The meaning of each sound pattern must be socialised and practised beforehand to avoid confusion.

Can reach hamlets, coastal areas, scattered settlements, markets, small ports, and areas with weak telecommunications signals.

Becomes a link between villages, command posts, volunteers, officials, and BPBD when mobile communication is disrupted. Such networks also allow field information to move in two directions.

They are a ‘human communication network’ that can ensure messages are truly received, understood, and passed on to residents who are not active media users.

For communities that still have telecommunications access, location-based short messages and WhatsApp groups/official channels can accelerate the dissemination of updates. Digital messages need to be consistent with messages delivered through offline channels.

Functions to expand reach, provide context from official sources, and prevent information vacuums that are easily filled by speculation.

Used for rapid updates, infographics, short videos, maps, FAQs, and debunking. Content must be easy to re-share by local government, media, KOLs, communities, and local networks.

Still needed at village offices, community health centres, schools, markets, terminals, ports, evacuation sites, and public service points, especially when digital access is limited.

‘In an emergency, the best communication channel is not always the most sophisticated channel, but the channel most likely to be received, trusted, understood, and immediately turned into action by the community.’

To avoid confusion, all channels must carry the same substance: what is happening, which areas are affected, what to do, what not to do, official information sources, and when the next update will be given. Central messages need to be translated into local context by BPBD and local government without changing technical facts. For areas with language diversity, information also needs to be delivered in regional languages or easily understood audio forms.

Most importantly, communication must be two-way. Community radio, volunteers, village officials, health centres, schools, and community leaders are not only message deliverers, but also ‘social sensors’ that provide feedback: whether masks are available, whether there are residents who have not received information, whether rumours are emerging, whether vulnerable groups need assistance, and whether government instructions are understood. Thus, stakeholder engagement truly works as a risk communication system, not merely a list of parties involved.

Do not conclude risk solely from sounds, videos, or social media posts.

Obey the 3 km radius, reduce ash exposure, and prepare yourself if new directives are issued.

Prioritise PVMBG/Geological Agency, BMKG, BNPB/BPBD, and relevant official authorities.

The December 2018 Banten tsunami taught that disasters can develop very quickly, while the public needs clear messages amid uncertainty. In the book I wrote about tsunami risk communication through stakeholder engagement, I positioned stakeholder involvement not as a complement, but as part of the safety system. Information must move from technical agencies to local government, media, communities, families, and individuals, and at the same time, reports from the field must be able to return to the decision-making system.

Today, that lesson remains relevant. Monitoring technology is improving, information channels are multiplying, but communication challenges are also becoming more complex. The speed of social media means correct information and incorrect information can circulate at the same pace. Therefore, risk literacy becomes a very important public capability: not overreacting, not underestimating, and being able to distinguish official sources from speculation.

We cannot stop natural processes, but we can reduce their risks through science, preparedness, good communication, and solidarity. At the time this article was written, the continuous eruption episode had ended, but Level III (Siaga) status still applies and monitoring continues. So the most appropriate attitude is neither panic nor indifference.

Remain calm. Protect yourself from ash exposure. Obey the danger zone. Check travel conditions before departing. Know evacuation routes if you live in a coastal area. And no less important: do not spread unverified information.

‘In risk communication, the strongest calm is calm born of knowledge. The most effective vigilance is vigilance that knows what to do.’

The state, technical agencies, local government, media, communities, and the public have complementary roles. When official information is trusted, understood, and translated into simple actions, public communication does not merely reassure; it becomes part of disaster mitigation itself.