Moreover, the success of the hazard management was only possible through the trust fostered between the locals, the volcanologists, and the authorities. The database gathers unrest of volcanoes all over the world and makes the carefully organised data public so it can be used to construct models that help forecast eruptions. If a repeat of the eruption of Pinatubo were to occur today, the repercussions would have been much greater.
What consequences could result? Pinatubo data can be visualised and downloaded using WOVOdat interactive online tools. Click on the links below for more. Skip to main content. Earth Observatory Blog. HAN Suling Cheryl. Raymundo S. Punongbayan, Christopher G. Newhall, Ma. Leonila P. Pinatubo mostly noted for a failed geothermal development project. Eruptions of Mount Pinatubo Pinatubo has had at least 6 periods of activity with large explosive eruptions in its past 35, years prior to the eruption.
The eruption in this context actually ranks as one of the smaller eruptions. An eruption, which occurred 35, years ago and probably created the caldera, was likely much bigger.
Show interactive Map. Last earthquakes nearby. View recent quakes. Heavy monsoon rains caused by typhoon Kiko generated heavy floods in August It was about ten times larger than the eruption of Mount St. Helens in Latest satellite images. Show more. First visit to our site? The stakes were high: Just 6 years earlier, Nevado del Ruiz in Colombia erupted and killed more than 23, people.
The scheme had to be effective and easily digestible—enough so that they could convince tens of thousands of people living around the volcano, who spoke several different dialects and even different languages , to evacuate. The team persevered, gathering local leaders of cities, towns, and small villages to explain the dangers and answer questions.
Part of this educational campaign involved showing gruesome video footage from the Nevado del Ruiz tragedy that depicted destructive ash flows, volcanic mudflows, ashfalls, landslides, lava flows, and more. Here scientists learned a powerful lesson in hazard mitigation. By early June, officials called for the evacuation of 25, people living in the area, including American service people at Clark Air Base and the U.
Naval Station at Subic Bay. Never before had such a widespread evacuation attempt been made before a volcanic eruption. By the time the volcano erupted on 15 June, scientists and public officials had convinced more than 65, people to evacuate. In , scientists had to look up information in books, make photocopies, and fax information to each other, Ewert said.
This was a time before GPS and before data could be sent via satellite. Smartphones were science fiction. One of these rumors claimed that a 3-mile-long fissure had formed after the eruption and that the nearby city of Olongapo would soon be hit by a giant lateral blast.
Magma can be classified into types that distinguish how much silica they contain and how viscous they are, among other characteristics. Silicic magma—made of dacite or rhyolite—is stickier and more viscous. It holds more gas that when depressurized, erupts more explosively. Studies of lava deposits after Pinatubo exploded revealed something curious: minerals juxtaposed that would not normally coexist together had magma come from one source, Newhall explained.
Thermal signatures—for example, crystals partially resorbing, chemical diffusion between crystals—suggested that magma was initially a mix of basalt and dacite prior to the eruption. But by the end of the eruption, magma was fully dacite. Instead, it rose into the dacite and mixed with it. But how? First, when the fresh, water-rich, and considerably hotter basalt hit the cooler dacite reservoir, the basalt crystallized, Newhall explained.
That added even more volatiles. The resulting slurry was still less dense than its surroundings, so it kept rising and was the first erupted. Eventually, the dacite itself heated enough to rise to the surface and erupt. This magma mixing manifested as subtly rumbling quakes that at times lasted about a minute long, called deep long-period DLP earthquakes.
Long-period earthquakes indicate that magma is intruding into surrounding rock , but scientists had more frequently observed these events at depths less than 10 kilometers. Before Pinatubo, DLP earthquakes had been rarely observed and were not fully understood.
Collecting this information involves studying crystals of cooled lava after an eruption, Ewert said.
This implied that emissions of water vapor and carbon dioxide—the gases that dominate emissions—were also more than scientists expected. But a whopping 17 megatons of sulfur dioxide was released by the explosion, as measured by satellite spectrometer.
This implied that large amounts of gas could accumulate as bubbles and remain in the magma chamber, Newhall explained. Because this excess gas makes an eruption more explosive, it might even be that such free gas is required for a Pinatubo-like eruption, Newhall said. If volatiles are already in excess, they can expand immediately once the pressure drops, without any delay from diffusing through melt.
Knowing that magmas can hold excess gas can help with forecasting efforts, Newhall explained. For example, if a volcano has been plugged since its previous eruption yet has been continuously recharged with fresh magma and gas from depth, scientists can examine the time between its eruptions to gauge whether the volcano has accumulated enough excess gas to make it particularly explosive.
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