International Meeting Addresses Volcano Hazard Assessment

USGS Hawaiian Volcano Observatory geologist Frank Trusdell (right) discusses methodologies for lava flow hazard assessment in Hawaii with a volcanology colleague from Ethiopia during the recent Volcano Observatory Best Practices Workshop in Vancouver, Washington. Eruptions in the East African Rift bear some broad similarities to Hawaiian volcano rift zone eruptions. USGS photo.

There are more than 1,500 active volcanoes on Earth. With many millions people living and working in their shadows, developing ways to co-exist safely with potential volcanic threat is essential. To do so, those at risk need to know the type and severity of hazards they may face.

One of the primary jobs of volcanologists is to prepare evaluations or assessments of volcano hazards. This information—often in the form of maps and reports—is intended for use by a wide range of individuals and groups that would potentially be impacted by future volcanic activity or are responsible for planning and responding to eruptions. These include residents, emergency managers, land use planners, utility providers and insurers.

In mid-November 2016, 70 representatives of volcano observatories from 20 volcanically active nations around the world came together in Vancouver, Washington, to share techniques, lessons learned, and challenges faced in preparing effective, useful volcano hazard maps and analyses. This meeting was the third in a series of Volcano Observatory Best Practices workshops, and the first to be held in the United States.

Sponsored by the U.S. Geological Survey, the U.S. Agency for International Development, the International Association of Volcanology and the Earth’s Interior, the World Organization of Volcano Observatories, and the Istituto Nazionale di Geofisica and Volcanologia, the four-day workshop featured formal presentations about volcano hazard assessments in Indonesia, Colombia, the Philippines, Ecuador, New Zealand, Iceland, Mexico, Italy and the U.S.

Throughout the workshop, participants shared examples of hazard assessment products developed for specific volcanoes in their respective countries, and described the science behind the products and how they have been used. Not surprisingly, styles and approaches vary from country to country, but some commonalities emerged.

To create such assessments, volcanologists must determine what hazards are likely to affect a particular area. In order to answer this question, scientists must have a thorough understanding of a volcano’s past eruptive history and behavior. This understanding requires extensive and careful geologic studies of a volcano to completely characterize its style and frequency of activity.

Even further work is required to develop a conceptual model for how that volcano actually behaves over time, an effort that can take many years to complete. Not all volcano observatories have the necessary resources to conduct the detailed work that many in the scientific community consider absolutely essential. In those cases, early assessments must be done with the geologic information that is available, even if it is incomplete.

Other workshop presentations focused on tools for portraying volcano hazards. Increasingly, scientists are using mathematical models and modern computer graphics to simulate volcanic processes, such as lava flows or lahars (mudflows). These models can help people visualize areas that would likely be affected during a variety of eruption conditions. This approach is more quantitative and provides more detail, but models require assumptions that contain some degree of uncertainty.

Another topic addressed in the workshop is how to ensure that users of hazard assessments understand the information provided in the assessments and know how to incorporate conclusions of the assessments into their decision-making process. Workshop participants agreed that engaging stakeholders prior to the creation of hazard assessments is critical to make certain that the resulting information is understandable and useful. Lively discussion ensued as colleagues gathered around several dozen posters displaying examples of hazard assessments from around the world.

A tangible outcome of the workshop will be a report identifying initial best practices for preparing volcano hazard assessments. The report can help guide scientists and their nation’s policies as they complete this work. Closer to home, U.S. participants renewed their commitment to develop a plan to guide the ‘next generation’ of volcano hazard assessments for the highest priority volcanoes, including those in Hawaii.

For information on the current long-term hazard assessment for Hawaiian volcanoes, go online.

Volcano Activity Updates

Kīlauea continues to erupt at its summit and East Rift Zone. This past week, the summit lava lake level varied between about 21to 66 feet below the vent rim. The 61g lava flow continued to enter the ocean near Kamokuna. On Dec. 1, a new breakout from the 61g vent area on the flank of Pu‘u ‘Ō‘ō sent a small surface flow to the east, on top of existing 61g flows. The 61g lava flows do not pose an immediate threat to nearby communities.

Mauna Loa is not erupting. During the past week, about a dozen small earthquakes occurred primarily northwest of the summit caldera at depths between 3 and 8 miles. Deformation related to inflation of a magma reservoir beneath the summit and upper Southwest Rift Zone continues, with inflation occurring mainly in the southwestern part of the magma storage complex.

No earthquakes were reported felt on the Island of Hawaiʻi this past week.

Volcano Watch is a weekly article and activity update written by U.S. Geological Survey Hawaiian Volcano Observatory scientists and affiliates.

Call for summary updates at (808) 967-8862 (Kīlauea) or (808) 967-8866 (Mauna Loa); email questions to [email protected].