November 19, 2009
A weekly feature provided by scientists at the Hawaiian Volcano Observatory.
For volcanoes, acting locally causes effects globally
In a few short weeks, scientists from the U. S. Geological Survey's Hawaiian Volcano Observatory (HVO) A visit to Kīlauea can bring a sense of awe and appreciation for the earth's volcanoes. Over the past weeks, the east rift eruption has produced multiple ocean entries, and photogenic surface flows, which have touched off fiery infernos in the rare remaining kipuka (island of vegetation). The flows came uncomfortably close to the tourist trail that has carried tens of thousands of admiring visitors, and engulfed and destroyed a lone structure. Not to be outdone, the Halema`uma`u Overlook vent has offered glimpses of a rising and falling lava pond, as well as a landscape of molten, shifting holes opening into a deep cavity within the vent.
In contrast, living downwind of Kīlauea's copious gas emissions, or in the path of lava flows, can bring an exclamation of "auwe" ("oh dear!" or "Alas!"). Since the onset of summit activity in 2008, impacts from Kīlauea have increased. Hawai`i County was declared a federal natural disaster area owing to agricultural losses, and air quality in downwind communities frequently exceeded federal and state standards.
While Kīlauea does contribute modest amounts of gasses to the atmosphere, most impacts are local to Hawai`i. We might count ourselves lucky because growing evidence suggests that very large volcanic eruptions have extreme effects on the global environment. For example, massive volcanic activity around 60-70 million years ago occurred on the Deccan Plateau in what is now west-central India. This activity, which produced the Deccan Traps (from the Swedish word for stairs, Trappa, which refers to the feature's step-like landscape), is one of the largest known eruptions to occur since the Earth's initial formation.
There are distinct similarities between Kīlauea and the Deccan Traps. While Kīlauea is being created by the Hawai`i hot spot, the Deccan Traps were likely a product of the Reunion hot spot. The eruptive style of both can be characterized by multiple volcanic events separated by relatively short repose periods. They produce basaltic lava and have flow units with pahoehoe toes as the basic building block. In fact, scientists have studied Kīlauea's active volcanism as an analog for processes that would have created the Deccan Traps.
During the 0.5 million years or so since Kīlauea first began growing from the floor of the ocean, 1,400 square kilometers (540 square miles) have been covered by lava, or about 1/7 the area of Hawai`i Island. The Deccan Traps currently cover 500,000 square kilometers (190,000 square miles), an area somewhat greater than that of California. During its peak, which likely lasted less than 1 million years, the eruption rate of the Deccan Traps was at least 15 times that of Kīlauea's current eruption rate, or at least 25 times that of Kīlauea's more modest lifetime eruption rate.
The timing of the Deccan Traps is intriguing, with the peak in activity occurring at around 65 million years ago. Movie buffs and dinosaur fans might recall the tagline for the 1993 movie Jurassic Park: "An Adventure 65 Million Years in the Making," referring to the timing of the transition between the Cretaceous and Tertiary periods. Known as the K-T boundary, it was characterized by mass extinction of species, including the non-avian dinosaurs.
There is strong evidence that the impact of a large asteroid or comet contributed to this mass extinction due to the presence of enriched iridium in the fossil record at the K-T boundary. Iridium is an element that is much less abundant in the earth's crust than in meteorites, and, thus, likely originated from space. The Chicxulub impact crater on the Yucatan Peninsula, Mexico, has been identified as a likely candidate for a K-T impact event.
However, growing evidence suggests that volcanic activity from the Deccan Traps was a significant contributor to the mass extinction event. Recent studies examining the fossil record were able to correlate an abrupt change at the K-T boundary in species of tiny sea creatures known as foraminifera, with the main eruptive pulse in the Deccan Traps.
Volcanoes great and small can affect life on earth, from contributing to the extinction of dinosaurs to impacting Kīlauea's neighbors.
Kīlauea Activity Update
Lava continues to erupt from the TEB vent on Kīlauea's east rift zone and flow through tubes to the ocean at two locations—Waikupanaha and west Waikupanaha. Small surface flows have been sporadically active on the coastal plain for the last several weeks. In the past week, these surface flows were scattered mostly over a broad area more than 1 km to the west of the Hawai`i County lava viewing trail.
Glow above the vent at Kīlauea's summit has been visible at night from the Jaggar Museum. Incandescent openings, sometimes providing views of the lava surface, were visible on the floor of the vent cavity throughout the week by the Webcam perched on the rim of Halema`uma`u Crater. Volcanic gas emissions remain elevated, resulting in high concentrations of sulfur dioxide downwind.
One earthquake beneath Hawai`i Island was reported felt this past week. A magnitude-2.8 earthquake occurred at 6:04 a.m., H.s.t., on Sunday, November 15, 2009, and was located 3 km (5 miles) north of Paa`auilo at a depth of 11 km (7 miles).
Visit our Web site (http://hvo.wr.usgs.gov) for detailed Kīlauea and Mauna Loa activity updates, recent volcano photos, recent earthquakes, and more; call (808) 967-8862 for a Kīlauea activity summary; email questions to askHVO@usgs.gov.
Updated: November 29, 2009 (pnf)