Written by Dalton Alighieri.
Image credit: Mount Datun and Zhuzihu by Peellden / Wikimedia, license: CC BY-SA 3.0.
Parts of Taipei and New Taipei are not only at risk of earthquake- and typhoon-induced landslides and mudslides but also possible volcanic muddy debris movements, known as lahars, and faster and hotter flows of volcanic materials, gas, and ash called pyroclastic density currents in the unspecified future. However improbable it is that these occur in segments of the two jurisdictions in the 21st century, the threats they pose cannot be taken lightly. Tens of thousands of people died in such phenomena during the 1902 Mount Pelée (Martinique Island) and 1985 Nevado del Ruiz (Colombia) eruptions and other similar volcanic events in the 20th century. The utter terror and sadness of one of these happenings was captured, in part, by photographer Frank Fournier’s photograph of thirteen-year-old Colombian schoolgirl Omayra Sánchez Garzón, who was trapped in heavy debris and unsanitary fluids and suffered for days before dying.
Lahars, especially after initial eruptions or earthquakes and heavy rainfalls or waterway failures, and pyroclastic density currents, as well as rock projectiles, ash clouds, and other potential future hazards to portions of Taipei and New Taipei, could come from the non-extinct Tatun Volcano Group (TVG), which rises above the low-lying Taipei Basin and includes mountains that have erupted before. Volcanic materials from eruptions have been found in earth samples collected from sections of the two jurisdictions, which encompass both urban and non‑urban areas. It is inferred that beneath the surface of the TVG is magma. The probable presence of magma, the heat and chemicals it releases, and the hydrothermal system it influences may cause, as documented in some areas, seismic activity, gas emissions, acidic waters, fluctuating water and land surface temperatures, minor ground deformation, and localised vegetation die-off and barren landscapes near vents. These were seen, though not at the same levels or in the exact ways, across the Luzon Strait at Mount Pinatubo (Philippines) before it erupted in 1991 and at other volcanoes during periods of unrest but also quiescence. That said, Pinatubo, which had rapidly accelerating and strong, coherent multi‑parameter eruption precursors that were detected, was much more unstable in the early 1990s than the TVG is in the mid-2020s. TVG volcanic and hydrothermal system changes, which can be brought on by both magmatic and non-magmatic processes (tectonic, subsurface fluid‑related, etc.), do not necessarily indicate that unrest is escalating or that eruption probability is increasing.
Like Pinatubo, the TVG has shared and unshared characteristics with pre-eruption Pelée and Nevado del Ruiz. The TVG’s volcanic system type and geologic framework, current geochemical and geophysical activities, and time since a last eruption make it difficult to find a high-match analogue across all criteria. No two volcanic systems and surrounding environments are identical, and further scholarship on the differences, ranging from nuances to large dissimilarities, between the TVG and other volcanoes is needed. Moreover, there is no complete or conclusive data about what is going on beneath the surface of the TVG or any other volcano, and opinions and interpretations vary about what the system is and is not capable of and when. Be that as it may, technologies and research have advanced significantly since the Pelée eruption. Hundreds died in the Pinatubo eruption, but the detection before the cataclysm gave authorities time to move many more people to safety.
An event, if sizable, in addition to loss of life, could have broad and far-reaching economic consequences. If volcanic activities were to affect the power, energy, and transportation systems and cargo entry and exit points, displace the labour force, and/or cause air and water contamination from ash, Taiwan’s semiconductor and electronics manufacturing and supply chain, as well as other industries, could be hindered in certain areas. The aforementioned could have ramifications for the world economy and thus geopolitics. Note, the Pinatubo eruption, which degraded bases, partly led to the reduction of United States military forces in the Philippines. Regarding duration, while a volcanic explosion can be a singular event on one day, the eruption process, particularly ash-venting, can last weeks or months. Furthermore, recovery and normalisation, including repairing and rebuilding, environmental remediation, and macroeconomic stabilisation, could take years.
The damage and destruction caused by possible, though not certain, TVG eruptions in the future would depend on the location of the eruptions, their scale on the Volcanic Explosivity Index (VEI), the weather, and other factors. Generally, areas closer to the TVG are more at risk, and smaller eruptions are much more probable than larger ones. The types of eruptions, such as phreatic (steam-driven), magmatic, or hybrid phreatomagmatic, are other determinants. The positions of certain population centres and infrastructure at elevations below potential TVG eruption sites make them vulnerable to gravity-driven volcanic processes. Moreover, the population density near TVG is much higher than it was for Pelée, Nevado del Ruiz, and Pinatubo. The geological, topographic, and demographic realities combined form possible risks that warrant increased and continual but level-headed dialogue and measures.
The TVG has been and continues to be researched by various scientists and entities, such as Academia Sinica’s Institute of Earth Sciences, as one can find by reading peer-reviewed journal articles on Tatun listed in Google Scholar and elsewhere. The affiliated Taiwan Volcano Observatory at Tatun in Yangmingshan National Park is at the forefront of TVG monitoring. Accompanying these are other government organisations involved in data collection and disaster and emergency management planning and readiness. That said, much more can be done to enhance advanced preparedness and population safety.
The author’s ten recommendations, based on a review of the literature, include: 1) Continue identifying critical gaps in past studies, including hazard mapping and simulations and probabilistic hazard assessments, and prioritise new initiatives based on acquiring high-value missing information; 2) Create additional reports based on effective strategies taken in the past and presently by other cities with non-extinct volcanoes (e.g., Kagoshima (Japan) standards); 3) Increase funding, manpower, and equipment for TVG studies, observation, and eruption responses; 4) Expand the hiring of domestic and international staff and consultants in fields beyond purely geology (e.g., chemistry, physics, computer and data science, hydrology, engineering, public policy and health, economics, etc.) as determined to be pertinent for adequate multidisciplinary coverage; 5) Increase engagement with and assistance from volcanologists and agencies from other countries, including but not limited to the United States Geological Survey (USGS), as was done for Pinatubo before it erupted; 6) Acquire more state-of-the-art scientific instruments, especially hydrothermal items, from domestic companies or import if technologically better as well as encourage new inventions; 7) Heighten communication and coordination, plus data sharing and integration, regarding possible threats among the various public and private institutions that operate in Taipei and New Taipei and beyond and repeatedly clarify unified command and final decision-making authority; 8) Enhance public outreach, eruption warning systems, and evacuation, sheltering, and medical plans and education; 9) Harden and augment vulnerable critical infrastructure where feasible; 10) Constantly reevaluate actions based on the latest data and international best practices.
These measures should be carried out sooner rather than later, but in a competent and calm manner that does not cause alarm. On March 31, 2018, a number of Taipei residents panicked or became confused when a government organisation issued a poorly written mobile phone alert message for a volcano emergency drill. Drills, mock alerts, and tests should be clearly identified as such, especially at the beginning of the broadcasts, and warnings about their issuance should be given to the population in advance. Concerning writings on volcanoes, there are socioeconomic and political sensitivities regarding real estate, development, and more that necessitate factual backing and careful word choice. There are ongoing and planned construction projects, such as those in the Beitou-Shilin Technology Park, in areas between the TVG and low-lying rivers, and top-quality information dissemination must accompany the science on the region. This article is meant to continue the dialogue about the TVG and is not a technical paper, impact study, policy roadmap, or related plan. The author acknowledges his writing’s limitations in the depths of geological, economic, public administration, and other areas of coverage, as well as the treatment of the comparisons, with their many complexities and intricacies that can be expanded on. The most up‑to‑date information on the volcanic system is available through official government platforms.
Although eruptions are possible, it is important to note that TVG events within our lifetimes are not imminent. Mount Baker (Washington) and Mammoth Mountain (California), for example, both had unrest in the 20th century but did not go up. However, as the old saying goes, “It is better to be safe than sorry.” Baker did not blow, but Mount St. Helens, also in the state of Washington, did in 1980. The costs of inaction could be far greater than action in these contexts. Omayra Sánchez Garzón and others below Nevado del Ruiz were not properly alerted and relocated before it erupted. However, joint domestic and international efforts involving advanced and proven methods and modalities, including increased monitoring and rapid but orderly large evacuations, before the Pinatubo eruption saved numerous lives.
Dalton Alighieri is an independent researcher and writer based in the United States who focuses on volcanic threats in the Americas and Asia-Pacific. He synthesises global historical precedents with contemporary scientific findings and advocates for multidisciplinary, inter-organisational, and international disaster risk management. His work sits at the critical intersection of geohazard studies and public policy.
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