Floating Volcanic Pumice Threatens Livelihoods in Papua New Guinea

Floating pumice from the Titan Ridge underwater volcano in the Bismarck Sea is blocking coastal access and threatening food security in Papua New Guinea’s Manus Province. According to PNG Disaster Minister Billy Joseph, these volcanic rock rafts disrupt essential boat travel to markets, schools, and healthcare services in coastal communities.

Since May 9, the Titan Ridge eruption has released massive quantities of pumice—a porous, lightweight volcanic rock—into the ocean. European Space Agency imagery shows white plumes and grey rafts of this rock spreading from the eruption site. In Manus Province, these rafts have accumulated along waterways in thicknesses of two to five meters, leaving some residents able to walk on what was previously open water.

Why is the Titan Ridge eruption creating floating rock?

Pumice forms when gas-rich magma erupts and cools rapidly. The escaping gas creates countless tiny holes, making the rock light enough to float. These individual pieces clump together into enormous rafts that can cover thousands of square kilometers.

While many assume these rocks sink quickly, research indicates they can remain buoyant for years. Ocean currents, winds, and storms redistribute the pumice across vast distances long after the volcanic activity stops.

How long will pumice rafts disrupt Manus Province?

Disruptions in Manus Province could last for months or years. This projection is based on previous submarine eruptions, such as the 2012 eruption of the Havre volcano north of New Zealand. In that instance, pumice traveled thousands of kilometers, reaching Queensland eight months later and Tasmania more than a year after the event.

Because the pumice is already in the water, the end of the Titan Ridge eruption won’t immediately clear the coastlines. The material will continue to drift, potentially re-entering waterways as seasonal winds shift.

What happens when pumice hits coastal economies?

The economic impact depends heavily on a region’s infrastructure. In Manus, the ocean is the primary source of income and sustenance. When pumice blocks boat routes, it cuts off access to fishing grounds and essential supplies, creating an immediate food security risk according to Minister Billy Joseph.

A comparison with the 2021 Fukutoku-Oka-no-Ba eruption in Japan reveals the scale of potential damage. In Japan, pumice clogged 71 harbors and marinas, damaging hundreds of vessel engines and disrupting tourism. The economic cost in the Okinawa Prefecture alone exceeded 515 million yen.

Japan’s recovery was aided by federal resources and an expenditure of over 1 billion yen for cleanup. In contrast, Manus communities rely on manual labor to clear shorelines, making them more vulnerable to long-term disruption.

Could this eruption damage marine ecosystems?

Yes. Evidence from previous eruptions suggests two primary ecological threats. First, some fish species mistake floating pumice for food. Following the 2021 Fukutoku-Oka-no-Ba event, scientists found dead farmed fish with stomachs full of volcanic rock.

Second, pumice rafts can physically collide with shallow-water coral colonies. According to research on the 2022 Hunga Tonga-Hunga Ha’apai eruption, volcanic particles suspended in the water can reduce light penetration. This blocks the sunlight that coral reefs and other marine ecosystems need to survive.

Frequently Asked Questions

Does floating pumice eventually sink?
Some does, but much of it remains afloat for years. Research shows that ocean currents and storms keep pumice moving across the ocean long after an eruption ends.

Is the pumice dangerous to touch?
Pumice is highly abrasive. While not chemically toxic, the rough texture can cause skin irritation or cuts if handled without protection.

Can pumice rafts be easily removed?
No. The Japan experience showed that even with heavy machinery, most rafts only cleared when seasonal winds shifted. Manual removal is slow and only effective for small shoreline areas.

To learn more about how volcanic activity affects global shipping and ecology, explore our guide on submarine volcanism or visit the European Space Agency for satellite monitoring updates.