When will that volcano stop erupting?

Answers to your questions about the news.
April 24 2006 6:45 PM

When Will That Volcano Stop Erupting?

It could be thousands of years.

Download the MP3 audio version of this story here, or sign up for The Explainer's free daily podcast on iTunes.

A state of emergency has been declared for part of Peru, where a dome of lava continues to expand from the crater of the Ubinas volcano. The volcano began to erupt three weeks ago, and over the weekend authorities told those remaining in local villages to evacuate. How long can an eruption last?

Hours, days, or years. The median length of a volcanic eruption is seven weeks. About half of recorded eruptions last less than two months, with a tenth taking no more than a day. Almost 20 percent go on for more than a year, and some last for much longer.

Daniel Engber Daniel Engber

Daniel Engber is a columnist for Slate

Advertisement

An eruption begins when volcanic gases or molten rocks start to pop out of the crater. You can get a pretty good idea of how long it will last by reviewing previous eruptions from the same volcano. Alaska's Augustine volcano started to erupt in January and has continued to belch lava on a time scale similar to that of the eruptions in 1976 and 1986. In all three events, an initial series of explosions took place over a week or two, followed by several months of dome-building eruption.

Every once in a while an eruption goes on much longer than expected. Kilauea volcano in Hawaii has been producing lava flows since 1983 without a break, despite a history of much shorter eruptions. The volcano on the Mediterranean island of Stromboli has been spitting out molten rock for at least 2,400 years. (An "open vent" at Stromboli allows magma to emerge almost continuously, with little explosions every 20 minutes or so.) At least 14 other volcanoes have been erupting for more than 30 years.

If you measure an eruption by how much magma gets expelled, the biggest ones aren't necessarily the longest-lasting. In 1912, the Novarupta volcano in Alaska released 15 cubic kilometers of material over just two and a half days. It would take a marathoner like Kilauea another two centuries of continuous eruption to match that total.

It may be possible to predict the length of an eruption once it starts. Volcanologists have identified a connection between the amount of energy released at the peak of an eruption and the average energy that's released over the whole course of the event. That means you can make a pretty good guess about how long the eruption will last if you can figure out when it's peaking.

Got a question about today's news? Ask the Explainer.

Explainer thanks Stephen McNutt of the University of Alaska.

TODAY IN SLATE

The World

The Budget Disaster that Sabotaged the WHO’s Response to Ebola

Are the Attacks in Canada a Sign of ISIS on the Rise in the West?

PowerPoint Is the Worst, and Now It’s the Latest Way to Hack Into Your Computer

Is It Offensive When Kids Use Bad Words for Good Causes?

Fascinating Maps Based on Reddit, Craigslist, and OkCupid Data

Culturebox

The Real Secret of Serial

What reporter Sarah Koenig actually believes.

Culturebox

The Actual World

“Mount Thoreau” and the naming of things in the wilderness.

In Praise of 13th Grade: Why a Fifth Year of High School Is a Great Idea

A Comically Inane Court Opinion Just Upheld Puerto Rico’s Gay Marriage Ban

  News & Politics
Politics
Oct. 23 2014 3:55 PM Panda Sluggers Democrats are in trouble. Time to bash China.
  Business
Moneybox
Oct. 23 2014 5:53 PM Amazon Investors Suddenly Bearish on Losing Money
  Life
Outward
Oct. 23 2014 5:08 PM Why Is an Obscure 1968 Documentary in the Opening Credits of Transparent?
  Double X
The XX Factor
Oct. 23 2014 11:33 AM Watch Little Princesses Curse for the Feminist Cause
  Slate Plus
Working
Oct. 23 2014 11:28 AM Slate’s Working Podcast: Episode 2 Transcript Read what David Plotz asked Dr. Meri Kolbrener about her workday.
  Arts
Culturebox
Oct. 23 2014 6:07 PM Devil in a Trenchcoat Will the new NBC series bring Constantine into the mainstream, or ruin the character forever?
  Technology
Future Tense
Oct. 23 2014 5:53 PM South Florida’s Desperate Secession Movement
  Health & Science
Science
Oct. 23 2014 5:42 PM Seriously, Evolution: WTF? Why I love the most awkward, absurd, hacked-together species.
  Sports
Sports Nut
Oct. 20 2014 5:09 PM Keepaway, on Three. Ready—Break! On his record-breaking touchdown pass, Peyton Manning couldn’t even leave the celebration to chance.