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Volcanoes affect life on earth

Posted by feww on November 21, 2009

Volcano Watch: Acting locally causes effects globally

(Volcano Watch is a weekly article written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory, HVO.)

A visit to Kilauea 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).


Lava from Kilauea enters the ocean.

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 Halemaumau 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 Kilauea’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 Kilauea have increased.

Hawaii 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 Kilauea does contribute modest amounts of gasses to the atmosphere, most impacts are local to Hawaii. 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.


Kilauea – Active Lava Tube. Source: USGS

There are distinct similarities between Kilauea and the Deccan Traps. While Kilauea is being created by the Hawaii 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 Kilauea’s active volcanism as an analog for processes that would have created the Deccan Traps.

During the 0.5 million years or so since Kilauea first began growing from the floor of the ocean, 540 square miles have been covered by lava, or about 1/7 the area of Hawaii Island. The Deccan Traps currently cover 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 Kilauea’s current eruption rate, or at least 25 times that of Kilauea’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 Kilauea’s neighbors.

 

KILAUEA VOLCANO (CAVW #1302-01-)
19°25’16” N 155°17’13” W, Summit Elevation 4091 ft (1247 m)
Current Aviation Color Code: ORANGE
Current Volcano Alert Level: WATCH

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