’Tis the season for holiday travel, and in this week’s Volcano Watch, we will visit El Chichón Volcano, in the state of Chiapas, Mexico. While there are some notable similarities between the subtropical/tropical settings of Hawaii and Southern Mexico, the volcanic activity is distinct and may kindle gratitude in Hawaii residents for the predominantly gentle style of Kilauea’s modern activity.
El Chichón last erupted in 1982, in one of the most important volcanic events of the 20th century. Three explosive eruptions occurred over a period of a week, sending columns of gas and volcanic ash high into the stratosphere. The intensity of the eruption blasted away the summit dome of the volcano, and abundant ash fall and pyroclastic surges (massive burst of hot gas and volcanic rock fragments) destroyed nine towns.
The eruption of El Chichón was North America’s deadliest volcano disaster of the century. Destruction was the greatest within 6 miles of the volcano, where more than 2,000 people were killed and 20,000 people left homeless. Within a radius of 30 miles, or the distance from Kilauea’s summit south to Naalehu and north to Pepeekeo, at least 50 rural settlements were severely affected, and agricultural lands sustained enormous losses. Ash affected areas greater than 125 miles from the volcano (the distance from Kilauea to central Maui).
The global effects of the El Chichón eruption were far-reaching. While the volume of the eruption was similar to that of Mount St. Helens in 1980, El Chichón released about seven times the amount of sulfur dioxide gas. The sulfur content of the El Chichón magma was exceptionally high, and the gas and particle-rich eruptive plumes circled the entire globe within three weeks. The eruption cloud passed over Hawaii just days after the eruption, allowing detailed observations from instruments at the Mauna Loa Observatory.
The volcanic aerosol helped warm the stratosphere by about 7 degrees Fahrenheit, due to absorption of solar and terrestrial radiation. Typically, such a large eruption would cool the overall climate, particularly in the summer, by reducing the amount of solar radiation reaching the Earth’s surface. However, the eruption occurred simultaneously with one of the strongest El Niño events of the century. It produced a compensating warming signal; thus, no large cooling was observed for the year following the eruption. The fine ash and sulfuric-acid droplets in the atmosphere caused brilliant sunsets that were viewed from the northern hemisphere for the next few years.
Appearances can be deceiving, and the El Chichón eruption largely caught residents and officials by surprise. Prior to 1982, the 3,800-foot volcano was heavily forested and looked similar to adjacent non-volcanic peaks. Because the last major eruption occurred approximately 500 years before the present, the hazards of El Chichón were absent from recent memory.
There were some seismic precursors and the local indigenous Zoque population also reported that Piowacwe, the shape-changing goddess of El Chichón, visited nearby villages in the weeks prior to the activity announcing the eruption. There is now a strong emphasis on monitoring and research studies, with community training on volcanic risk, including evacuation exercises.
According to the Mayan calendar, around Dec. 21, 2012, a full cycle of creation is completed and a new cycle begins. While 2012 also marks the 30th anniversary of the devastating eruption of El Chichón, we enter the new cycle with world-class Mexican volcanologists and many modern studies of El Chichón as well as other explosive Mexican volcanoes. El Chichón will undoubtedly erupt again; however, efforts to create informed, prepared communities can help to avoid apocalyptic destruction, such as occurred in 1982.
The 30th anniversary of Kilauea’s ongoing east rift eruption is also just around the corner. You can check out the activities surrounding the upcoming celebration by visiting the Hawaiian Volcano Observatory website at hvo.wr.usgs.gov.
Kilauea activity update
A lava lake within the Halemaumau Overlook vent produced night-time glow that was visible from the Jaggar Museum overlook and via HVO’s webcam during the past week. A deflation-inflation cycle (DI event) at Kilauea’s summit was accompanied by significant drop in lava level last weekend. The lower level removed support for the rim of the lava lake, leading to several small collapses. By mid-week, the lava level has risen again, but stabilized at a level lower than that of the previous week.
On Kilauea’s east rift zone, surface lava flows are still active on the coastal plain and entering the ocean sporadically near Kupapau. The active flows straddle the eastern boundary of Hawaii Volcanoes National Park. Within Pu‘u ‘O]o, a small lava lake, partly hidden beneath a spatter cone, resides on the northeastern side of the crater floor. In addition, glow emanates from other points on the northwestern and southeastern parts of the crater floor.
Two earthquakes were reported felt in the past week on the Island of Hawaii. On Dec. 15, at 9:05 p.m., a magnitude-2.1 earthquake occurred 3 miles north of Captain Cook at a depth of 5 miles. On Dec. 17 at 4:14 p.m., a magnitude-2.3 earthquake occurred 3 miles southwest of Kapoho at a depth of 1.7 miles.
Visit the HVO website (http://hvo.wr.usgs.gov) for Volcano Awareness Month details and Kilauea, Mauna Loa, and Hualalai activity updates, recent volcano photos, recent earthquakes, and more; call 967-8862 for a Kilauea summary; email questions to askHVO@usgs.gov.
Volcano Watch (http://hvo.wr.usgs.gov/volcanowatch/) is a weekly article and activity update written by scientists at the U.S. Geological Survey`s Hawaiian Volcano Observatory.