How to Monitor and Mitigate Volcanic Hazards

Imagine living in the shadow of a giant that could awaken at any moment. For millions of people worldwide, this isn’t just imagination-it’s reality. Volcanoes are among nature’s most spectacular yet potentially deadly forces, capable of unleashing destruction with little warning. But here’s the hopeful truth: modern science has transformed how we monitor these sleeping giants and protect the communities around them. The 1991 eruption of Mount Pinatubo in the Philippines stands as a powerful testament to this-scientists successfully predicted one of the century’s largest eruptions, saving an estimated 5,000 lives through timely warnings and evacuations.

How scientists keep watch: Methods of monitoring volcanoes 🔗

Detecting volcanic unrest is like being a detective with an array of high-tech tools, each revealing different clues about what’s happening beneath the surface. Volcanologists employ multiple monitoring techniques because no single method can capture the full picture of volcanic activity.

Listening to the earth’s heartbeat with seismic sensors 🔗

When magma moves beneath a volcano, it creates earthquakes-lots of them. Seismic monitoring networks detect these volcanic earthquakes, which often serve as the earliest warning signs of volcanic unrest. Different types of earthquakes tell different stories: sharp, high-frequency tremors might indicate rock fracturing, while sustained, rhythmic vibrations called volcanic tremor suggest magma is actively moving through underground pathways. Before Mount Pinatubo’s 1991 eruption, seismometers recorded increasing earthquake activity, with 30 to 180 small earthquakes occurring daily in the months leading up to the major eruption.

Measuring the mountain’s breath: Ground deformation monitoring 🔗

Volcanoes quite literally swell and deflate as magma accumulates or drains from underground chambers. Ground deformation monitoring uses tools like GPS stations, tiltmeters, and satellite radar to detect these subtle changes-sometimes as small as a few millimeters. At Mount St. Helens in 1980, deformation monitoring detected a bulge on the north flank expanding by several meters per day before the devastating eruption. Today’s Global Navigation Satellite System (GNSS) stations and Interferometric Synthetic Aperture Radar (InSAR) provide continuous, precise measurements that can reveal magma movement weeks or even months before an eruption.

Sniffing out danger: Gas emission monitoring 🔗

As magma rises toward the surface, decreasing pressure causes dissolved gases to escape-much like opening a bottle of soda. Scientists monitor emissions of sulfur dioxide, carbon dioxide, and other volcanic gases using both ground-based sensors and airborne measurements. Changes in gas emissions often signal that magma is approaching the surface. Before Pinatubo’s eruption, sulfur dioxide emissions surged from 500 metric tons per day to over 5,000 metric tons per day within just two weeks-a clear warning that something significant was brewing beneath the volcano.

Watching from above: Remote sensing technologies 🔗

Satellites orbiting high above Earth provide a bird’s-eye view of volcanic activity, detecting thermal anomalies, ash clouds, and surface changes that might be invisible from the ground. These remote sensing tools are especially valuable for monitoring remote or inaccessible volcanoes, ensuring that even the most isolated volcanic systems don’t escape scientific scrutiny.

Speaking the same language: Volcano warning systems 🔗

Having sophisticated monitoring equipment is only half the battle-scientists must effectively communicate volcanic hazards to emergency managers and the public. This is where standardized warning systems become critical.

The color-coded approach: Alaska’s aviation color codes 🔗

Volcanic ash poses a severe threat to aircraft, capable of melting in jet engines and causing catastrophic failure. Alaska’s color-coded system uses four levels-Green, Yellow, Orange, and Red-to communicate volcanic threats to the aviation sector. Green indicates normal background activity, Yellow signals elevated unrest, Orange means heightened unrest with potential eruption or minor ash emission underway, and Red warns of significant ash emissions imminent or in progress. This simple, intuitive system has been successfully applied across Alaska, where volcanoes are monitored continuously to protect air traffic.

Ground-based alert levels: The USGS system 🔗

For communities living near volcanoes, a parallel system uses four alert levels: Normal, Advisory, Watch, and Warning. These terms describe the overall hazard level at a volcano, with Warning reserved for situations where a highly hazardous eruption is underway or imminent. The beauty of this system lies in its clarity-emergency managers know exactly what each level means and can take appropriate actions, from heightened monitoring at Advisory level to full-scale evacuations at Warning level.

Learning from Pinatubo: The power of timely warnings 🔗

Mount Pinatubo’s five-level alert system, introduced on May 13, 1991, became a model for volcanic crisis communication. Each level described increasing unrest and decreasing assurance that an eruption wouldn’t occur within specific timeframes. When seismic activity intensified dramatically on June 7, authorities raised the alert to Level 4, warning that an eruption was possible within 24 hours and recommending evacuations. Three days later, Level 5 was declared as the major eruption began. Despite some confusion about the exact meaning of alert levels-a valuable lesson for future communication strategies-approximately 60,000 people evacuated before the climactic eruption on June 15, saving thousands of lives.

Building resilience: Mitigation strategies for volcanic risks 🔗

While we can’t prevent volcanic eruptions, we can dramatically reduce their impact through thoughtful planning and preparedness measures.

Smart land use: Keeping people out of harm’s way 🔗

Land-use planning and zoning identify hazard zones around volcanoes based on the type, frequency, and magnitude of expected volcanic phenomena-lava flows, ashfall, and lahars (volcanic mudflows). By restricting development in high-risk areas and locating critical infrastructure like hospitals and power plants in safer zones, communities can minimize their exposure to volcanic hazards before disaster strikes.

Building to withstand: Structural mitigation measures 🔗

Where people must live near volcanoes, buildings can be designed to withstand volcanic hazards. Reinforced roofs prevent collapse under heavy ashfall loads, while ash-resistant designs protect critical infrastructure from the corrosive effects of volcanic ash. Building codes in volcanic regions should mandate these protective features, ensuring that structures can weather an eruption’s fury.

Physical barriers: Redirecting nature’s force 🔗

Sometimes, the best defense is a well-placed wall or channel. Engineers construct diversion channels and barriers to redirect lava flows or lahars away from populated areas and essential assets. While these structures can’t stop an eruption, they can guide its destructive forces toward less vulnerable locations, buying precious time for evacuations and reducing property damage.

Knowledge is power: Public awareness and education 🔗

The most sophisticated warning systems fail if communities don’t understand them or know how to respond. Public education programs teach residents about volcanic hazards, evacuation routes, and emergency procedures. Regular drills and community exercises ensure that when crisis strikes, people know exactly what to do. The success at Mount Pinatubo wasn’t just about technology-it was equally about an intensive educational campaign that ensured warnings were received, understood, and acted upon.

Planning for the worst: Evacuation strategies 🔗

Effective evacuation plans outline clear procedures, designated safe zones, and transportation arrangements for moving people away from threatened areas. These plans must consider vulnerable populations-the elderly, disabled, and low-income residents-who may need special assistance. Success depends on clear communication channels between scientists, authorities, and the public, adequate shelters and support services, and crucially, public trust in official information sources.

What do you think? How might your community improve its preparedness if it were located near an active volcano? And given the success at Mount Pinatubo, what lessons could be applied to other natural disaster warning systems beyond volcanic eruptions?

References

1. https://www.nps.gov/articles/volcano-monitoring.htm
2. https://www.britannica.com/science/volcano/Mount-Pinatubo-Philippines-1991
3. https://www.usgs.gov/publications/ground-deformation-and-gravity-volcano-monitoring
4. https://avo.alaska.edu/volcano/alertLevels
5. https://pubs.usgs.gov/pinatubo/punong2/
6. https://pubs.usgs.gov/fs/1997/fs113-97/
7. https://fiveable.me/volcanology/unit-13/volcano-hazard-mitigation-strategies/study-guide/Oz7JgsBzuXxhLUf8