Although the images of roiling lava flows demolishing homes and chewing up cars are terrifying, no fatalities caused by the volcanic activity have been reported. Findings from a database of global volcano fatalities published last year in the Journal of Applied Volcanology offer some clues as to why: Deaths linked to flowing lava are relatively rare, accounting for a tiny fraction of the world's volcano-driven mortality.
First, the basics: Volcanologist Sarah K. Brown of the University of Bristol and her colleagues compiled data on more than 278,000 global volcano deaths going back to the year 1500. They classified each of the fatalities by the precise cause of death because, as they explain with some understatement, "volcanoes can produce a number of potentially lethal hazards."
Those hazards include swift-flowing plumes of hot gas and volcanic matter known as pyroclastic density currents, volcanic tsunamis, volcanic mudflows, volcanic ash, flaming chunks of molten rock raining from the sky, avalanches, gas emissions, explosive steam ejections, lava flows and volcanic lightning.
Pyroclastic density currents (PDCs) are the No. 1 killers from volcanic eruptions, accounting for nearly 60,000 deaths since 1500. "In general, PDCs move too quickly for people to escape, and death is almost certain for those caught by a PDC," Brown and her colleagues explain. Statistically speaking, the record suggests that if 1,000 people get caught in a PDC, all but four of them will die.
Tsunamis are the second-biggest driver of volcano-related deaths, with nearly 57,000 fatalities recorded. The tsunami fueled by the 1883 eruption of Krakatau in Indonesia is estimated to account for 36,000 of those deaths.
Volcanic mudflows are the other big killer, causing more than 56,000 deaths. They can be hot enough to burn flesh, can extend hundreds of kilometers away from the source of the eruption and can occur for years after an eruption.
While lava flows loom large in the popular imagination, only 659 deaths by lava have been recorded since 1500. "Lavas normally advance slowly, allowing escape," Brown and colleagues explain. Hence, all those harrowing videos out of Hawaii showing people standing just yards away from bubbling lava are not quite as scary as we may think.
Many people also die in the months following volcanic eruptions from indirect causes, such as famine and disease. The database's catchall "indirect" category also includes transportation accidents related to the eruption, heart attacks suffered during strenuous cleanups after eruptions, and all manner of random misadventures that occur around volcanoes even when they're not actively erupting, such as falling into steam vents and being caught in a lava bench collapse.
From a global standpoint, volcano fatalities are quite rare in the United States relative to other nations, particularly places such as Indonesia and the Philippines. Indonesia alone accounts for more than 145,000 volcano-related deaths since 1500, more than half the database.
The United States, by contrast, has had just 708 volcano-related deaths. Since 1784, the year of the earliest recorded volcano fatality in areas that are part of the present-day United States, at least 421 of those have occurred as a direct or indirect result of volcanic activity at Kilauea in Hawaii -- the country's deadliest volcano and the source of the current lava event on the Big Island.
The bulk of the Kilauea deaths, an estimated 400, were the result of an explosive eruption in 1790. During that event, a large company of Hawaiian warriors "was engulfed in a stream of hurricane force winds, composed of hot steam and sulfuric gases" known as a pyroclastic surge, according to the National Park Service. Fossilized footprints dating to the time of the eruption remain on the slopes of Kilauea.
Since then, the volcano has been in a period of relative quiescence. In recent years, deaths associated with the volcano have tended to involve tourists and visitors falling into steam vents or inhaling noxious gases. Earlier this year, an experienced tour guide on the island died after being overcome by "a noxious steam cloud."
Washington's Mount St. Helens is the second-deadliest volcano in the modern-day United States, according to the volcano fatality database. An eruption in 1800 is thought to have been responsible for at least 100 deaths from starvation the following winter, according to the database's authors.
The more notorious 1980 eruption is linked to at least 57 direct deaths caused by pyroclastic density currents associated with the explosion. At least four more people died in accidents following the eruption, or after suffering heart attacks while shoveling ash.
Hawaii's Mauna Loa volcano killed 77 people in the course of an 1846 eruption, 46 as a result of a volcanogenic tsunami and 31 from volcanic mudflows.
The nation's fourth-deadliest volcano may come as a surprise: the Yellowstone caldera, which has lain dormant for tens of thousands of years. At least 23 park visitors have died there since record-keeping began; all of them fell into the park's famous thermal pools. Most recently, in 2016, a 23-year-old man left the park's designated walkways and slipped into a pool of boiling acidic water.
One final surprise on the list of the nation's deadly volcanoes: California's Mammoth Mountain, home to a large ski resort. Since 1998, four people have died there as a result of the venting of deadly carbon dioxide gas.
On the whole, however, volcano-related fatalities are relatively rare, particularly in the United States. Averaged out over the life of the Republic, volcanoes have killed about three people per year here, with the bulk of those deaths caused by a single event in Hawaii in 1790.
By contrast, lightning strikes typically kill more than 20 Americans in a given year.