A British-led hiking team narrowly escaped disaster yesterday when Mount Merapi, one of Indonesia's most active volcanoes, erupted without warning, sending a plume of ash and pyroclastic flow down its slopes. The incident, which occurred in the early morning hours local time, highlights the volatile nature of global travel markets and the unpredictable risks that investors must factor into their portfolios.

For the hikers, this was a brush with mortality. For the markets, it is a reminder that geopolitical and natural disaster risks are never fully priced in. The team, organised by a London-based adventure tour operator, was at an altitude of 2,900 metres when the mountain rumbled to life. Witnesses described a sudden roar, followed by a black cloud of ash that rose 5,000 metres into the air. The group, including 12 Britons and four local guides, retreated down a pre-identified escape route, reaching safety just minutes before the pyroclastic flow consumed their previous position.

Let us be clear: this is a tale of human survival, but also of economic disruption. Indonesia sits on the Pacific Ring of Fire, a zone of intense seismic activity that regularly disrupts supply chains for commodities such as coffee, rubber, and tin. Merapi, in particular, has a history of violent eruptions that have grounded flights across Southeast Asia, costing airlines millions in lost revenue and wreaking havoc on tourism-dependent economies.

The immediate market reaction was muted. Asian indices barely flickered, and gold, the traditional safe haven, held steady. But astute investors should not be lulled into complacency. The eruption serves as a stress test for insurance and reinsurance markets, which have been grappling with rising claims from climate-related events. A major eruption that shuts down airspace over Indonesia could trigger a cascade of losses, from cancelled holiday bookings to disrupted just-in-time manufacturing.

Remember the 2010 eruption of Eyjafjallajökull in Iceland. That relatively minor event grounded European flights for weeks, costing the global economy an estimated $5 billion. Merapi is far more dangerous. Its last major eruption in 2010 killed over 350 people and forced the evacuation of 400,000. If this current activity escalates, the economic fallout could dwarf that of the Icelandic ash cloud.

For now, the British hikers are safe, and the markets are sanguine. But the event should be a wake-up call for portfolio managers who have become too complacent about tail risks. Central banks, particularly the Bank of England, must also take note. A supply shock from a natural disaster could exacerbate the inflationary pressures that have already driven UK gilt yields higher. The Bank's Monetary Policy Committee would be wise to consider the potential for such events when setting interest rates.

In the meantime, investors should monitor Indonesian bond yields and the rupiah. Capital flight from emerging markets is a recurring theme, and a prolonged volcanic crisis could accelerate the outflow. The prudent investor will diversify into sectors that benefit from disaster preparedness: infrastructure, construction, and disaster recovery services.

As for the hiking team, they are lucky to be alive. Their story will no doubt inspire countless articles and social media posts. But for those of us in the financial world, the lesson is simpler: never underestimate the power of a black swan. Whether it comes from a volcano, a pandemic, or a political shock, the bottom line is always at risk.