A jökulhlaup on the Múlakvísl river is actively underway in southern Iceland, with glacial floodwaters surging from at least three separate sources beneath Mýrdalsjökull glacier. Authorities have warned of elevated volcanic gas pollution along the river corridor, and key road infrastructure in the area remains closed or at risk. Travelers heading toward the south coast highlands should check conditions before departing.
Key takeaways
- The Múlakvísl jökulhlaup is ongoing, fed by multiple subglacial meltwater sources beneath Mýrdalsjökull.
- Volcanic gases — including hydrogen sulfide (H₂S) and sulfur dioxide (SO₂) — pose a real health risk near the river.
- Road F232 and the Múlakvísl bridge area are closed or restricted; check Vegagerðin before traveling.
- The flood is strongly linked to geothermal and volcanic activity in the Katla caldera system under Mýrdalsjökull.
- Non-essential travel to the Múlakvísl corridor and adjacent highland routes is not recommended at this time.
Is the Múlakvísl jökulhlaup still ongoing?
Yes. The jökulhlaup — an Icelandic term for a glacial outburst flood, familiar to geologists worldwide — remains active at the time of publication. Water is discharging from at least three distinct subglacial meltwater outlets beneath Mýrdalsjökull, the large ice cap in southern Iceland that sits directly over the Katla volcanic system. Monitoring data from the Icelandic Meteorological Office (Veðurstofa Íslands) has recorded multiple velocity spikes in the Múlakvísl river, consistent with surging pulses of meltwater reaching the surface channel.
Jökulhlaups on the Múlakvísl are not unprecedented — Katla-related floods have occurred here throughout recorded Icelandic history — but the presence of multiple simultaneous sources makes this event more complex and harder to predict than a single-source flood. Scientists are monitoring the situation around the clock. The flood is not yet considered to have peaked, and water levels remain elevated and variable.
How dangerous is the gas pollution from the glacial flood?
Volcanic gas pollution is a serious and immediate hazard associated with this jökulhlaup. As meltwater forces its way through subglacial geothermal zones beneath Mýrdalsjökull, it carries dissolved gases — chiefly hydrogen sulfide (H₂S) and sulfur dioxide (SO₂) — to the surface. These gases accumulate in low-lying areas, depressions, and river valleys, where they can reach dangerous concentrations quickly and with little visible warning.
Hydrogen sulfide has a distinctive rotten-egg smell at low concentrations, but at higher levels it paralyzes the olfactory nerve — meaning you may stop smelling it precisely when it becomes most dangerous. Sulfur dioxide irritates the respiratory tract and can be life-threatening for people with asthma or other lung conditions.
Authorities have issued explicit warnings: people must not enter the river valley or approach the floodplain without professional gas-monitoring equipment. Wind direction governs where gases travel on any given hour, so conditions can change rapidly. Anyone in the vicinity who experiences dizziness, throat irritation, or eye burning should move upwind immediately and seek higher ground.
Which roads or bridges are closed due to the Múlakvísl flood?
Road closures are in effect in the flood-affected zone. The highland F-road network in the Mýrdalssandur area — including access routes toward and across the Múlakvísl — is closed to all traffic. The bridge over the Múlakvísl, which carries the main highland route across the river, is under threat and is not accessible to the public.
Travelers should check the following before any journey in southern Iceland:
- Vegagerðin (Icelandic Road and Coastal Administration): road.is for live road status and closures.
- Veðurstofa Íslands: en.vedur.is for flood warnings and gas hazard alerts.
- Almannavarnir (Department of Civil Protection and Emergency Management): almannavarnir.is for official safety advisories.
The Ring Road (Route 1) further south has not been directly closed at the time of writing, but conditions in the Mýrdalssandur outwash plain can change with little notice if floodwaters expand. Drivers passing through the area should stay on marked roads and not attempt to cross rivers or flooded surfaces independently — a rule that applies at all times in Iceland but is especially critical now.
Is this jökulhlaup linked to volcanic activity under Mýrdalsjökull?
Almost certainly, yes. Mýrdalsjökull sits directly over the Katla volcano, one of Iceland’s most powerful and historically active volcanoes. Katla has not had a confirmed full eruption since 1918, but it produces regular subglacial geothermal episodes that generate meltwater, seismic swarms, and — as now — jökulhlaups. Scientists at the Veðurstofa and the University of Iceland have monitored Katla intensively for decades precisely because of this risk.
A jökulhlaup originating from multiple subglacial sources simultaneously is consistent with elevated geothermal activity or a minor subglacial eruptive event within the Katla caldera. However, Icelandic authorities have not confirmed a full volcanic eruption at the time of writing. The distinction matters: a subglacial geothermal flood is dangerous but localized; a full Katla eruption would be a significantly larger event with consequences reaching beyond the immediate river system.
Seismic monitoring is ongoing. If the situation escalates toward an eruptive scenario, Almannavarnir will issue formal alerts through official channels and the media. Residents within the defined hazard zones around Mýrdalsjökull have established evacuation routes and plans, regularly rehearsed with local emergency services.
Should travelers avoid the area around Múlakvísl right now?
Yes. Non-essential travel to the Múlakvísl river corridor, the highland routes crossing Mýrdalssandur, and the slopes and access roads toward Mýrdalsjökull is strongly discouraged. The combination of an active glacial flood, volcanic gas hazards, closed roads, and unpredictable surge behavior makes this an environment where the risk cannot be managed by ordinary travelers without specialist equipment.
For those already in the broader south Iceland region — for example, on the popular coastal route between Vík í Mýrdal and Skaftafell — the situation warrants attention but does not necessarily require immediate evacuation unless authorities issue a formal alert for those specific areas. Vík, the small coastal town roughly 10 kilometers southwest of Mýrdalsjökull’s southern edge, has its own established evacuation protocols for Katla-related events. Local residents know these well.
Tourists staying in guesthouses or hotels between Selfoss and Kirkjubæjarklaustur should speak with their accommodation hosts, who will be monitoring the situation and can advise on local conditions. Do not rely solely on mobile data for safety information — in the highlands, connectivity is patchy.
If a trip to the area is planned for coming days, monitor Veðurstofa and Vegagerðin daily and be prepared to alter itineraries. Iceland’s highland and glacier routes can be extraordinary travel experiences under normal conditions, but this is not a normal period for the Múlakvísl corridor.
Frequently asked questions
What is a jökulhlaup and why does it happen on the Múlakvísl?
A jökulhlaup is a sudden, often violent outburst flood caused by the rapid melting of glacial ice — typically triggered by volcanic or geothermal heat beneath a glacier. The Múlakvísl river drains meltwater from Mýrdalsjökull, the ice cap covering the Katla volcano, making it one of Iceland’s most flood-prone river systems. When geothermal activity intensifies beneath the ice, meltwater accumulates in subglacial lakes and then bursts out suddenly, sending a surge of water, ice, and sediment down the river channel.
Can hydrogen sulfide gas from the jökulhlaup kill you?
Yes, at high concentrations, hydrogen sulfide (H₂S) is lethal. It causes rapid loss of consciousness and respiratory failure at concentrations above 300 parts per million. The danger near the Múlakvísl is that gas can pool invisibly in low-lying areas, and the warning smell disappears at dangerous levels. Anyone near the flood zone without certified gas-detection equipment should leave immediately.
Is Katla about to erupt?
Icelandic authorities have not declared a volcanic eruption at Katla at the time of writing. The current jökulhlaup is consistent with elevated subglacial geothermal activity, which Katla produces periodically without a full eruption breaking the ice surface. Scientists monitor Katla continuously, and any change in eruption status would be communicated immediately through Veðurstofa Íslands and Almannavarnir. The situation remains under close watch.
Is the Ring Road (Route 1) open through south Iceland?
The Ring Road has not been formally closed at the time of publication, but conditions in the Mýrdalssandur area are dynamic. Drivers should check road.is (Vegagerðin) in real time before and during any journey through the south coast. Do not cross any water on the road surface, even if it appears shallow — jökulhlaup floodwaters can be deceptively powerful and rise with little warning.
Where can I get the latest official updates on the Múlakvísl flood?
The most reliable sources are Veðurstofa Íslands (en.vedur.is) for meteorological and flood warnings, Vegagerðin (road.is) for road closures, and Almannavarnir (almannavarnir.is) for civil protection alerts. All three publish updates in English as well as Icelandic during significant natural events. Local radio — especially RÚV (Rás 1) — is also a critical information source if mobile data is unavailable in the highlands.
