Minor Phreatic Explosions at Bulusan in the Philippines
I write the Eruptions blog on Big Think. I've been mesmerized with volcanoes (and geology) all my life. It helps that part of my family comes from the shadow of Nevado del Ruiz in Colombia, where I could see first hand the deadly effects of volcanic eruptions. Since then, I've taken a bit of a winding path to become a volcanologist. I started as a history major at Williams College, almost went into radio, but ended up migrating to geology, including an undergraduate thesis on Vinalhaven Island, Maine. I followed this up by changing coast to get my Ph.D. from Oregon State University. Then I ran a MC-ICP-MS lab at University of Washington for a spell (and wrote for an indie rock website). I spent three years as a postdoctoral scholar at University of California - Davis studying the inner workings of magmatic systems. I am now an assistant professor at Denison University and have projects in New Zealand, Chile and Oregon.
I am fascinated by volcanoes, their eruptions and how those eruptions interact with the people who live around the volcanoes. I started this blog after getting frustrated with the news reports of volcanic eruptions. Most of them get the information wrong and/or are just sensationalistic. I will try to summarize eruptions as they occur, translate some of the volcanic processes that are happening and comment on the reports themselves.
And no matter what people tell you, I definitely do not have a cat named Tephra. (OK, I do).
You can find out more about my research by visiting my website. If you have any comments, questions or information, feel free to contact me at eruptionsblog at gmail dot com.
When it rains, it pours, my friends. The fall continues its volcanically noisy pace since late October as news comes in of ash explosions at Bulusan, the southernmost volcano on the island of Luzon in the Philippines. The volcano has produced a number of small explosions over the last few days - most producing plumes no more than 700 m / 2,300 feet-tall - but PHIVOLCS has still placed Bulusan on Alert Level 1 (which is still low). A dusting of ash was reported in areas close to the volcano. PHIVOLCS says that this behavior is typical for Bulusan when it enters restive phases, so an area of 4 km around the volcano have been designated a "danger zone". These new explosions appear to be phreatic events - that is, steam-driven explosions where water is heated by rising magma and flashes to steam. Most likely, the ash being produced is all old material from the crater area rather than any new magma. Seismicity has also increased at the volcano, suggesting moving magma.
Bulusan producing a small explosion in an undated image.
Bulusan is a fairly active dacite/rhyolite volcano that sits within a larger caldera system, so explosive eruptions are the norm for the volcano. In 2006/07, the volcano produced a series of VEI 2 eruptions that generated pyroclastic flows and lahars - along with an ash plume that reached nearly 7 km / 23,000 feet. If PHIVOLCS is right and these new phreatic explosions could herald a new eruption like that from 2006/07, we could see activity fairly similar to what is currently going on at Merapi - which is exactly what we might expect from these intermediate to silicic stratovolcanoes/composite volcanoes in volcanic arcs.
Top left: Mt. Bulusan in the Philippines.