The Republic of Madagascar consists entirely of islands – most notably the island of Madagascar, which is the fourth largest island in the world. Some 22 million people live on Madagascar’s islands, many in the shadows of extinct or active volcanoes. And yet, as far as she knows, Fara Rasoazanamparany is the first isotope geochemist from Madagascar to study volcanic activity in the country.
Rasoazanamparany is a postdoctoral research fellow in Miami University’s Department of Geology and Environmental Earth Science. Together with her supervisor, Dr. Elisabeth Widom, Rasoazanamparany is working to understand how frequently Madagascar’s volcanoes erupt and to discover the causes and sources of recent volcanism in the central and northern region of the island.
Earthquakes are common in Madagascar. A moderate earthquake measuring 5.3 on the Richter scale occurred in January 2013. In addition, hot springs and geysers dot the landscape, and geophysicists have discovered a dome of bulging magma beneath Madagascar’s surface. These are all signs that the area is still volcanically active.
In other words, Rasoazanamparany clarifies, “There’s a chance for future eruption.”
Just when and where that eruption might occur is of obvious concern for Madagascar’s 23 million residents.
“We don’t like to use the word prediction,” Widom says of herself and her fellow geologists.
That’s an understandable policy for scientists accustomed to working with time scales so large margins of error can be measured in centuries or even millennia. Still, it’s clear that when Widom says she wants to understand “the likelihood, the risk, and the hazards associated with a potential future eruption,” her interest is more than academic. All the more so for Rasoazanamparany, whose family still lives near the Itasy-Ankaratra volcanic field in the populous central part of the island of Madagascar, an area that includes the nation’s capital and largest city, Antananarivo.
To get a better fix on what the people of Madagascar may face in the future, Widom and Rasoazanamparany want to better understand Madagascar’s volcanic history. Supported by a $300,000 grant from the National Science Foundation (NSF), the pair plan to travel to Madagascar this coming summer. While there, they will collect lava samples from the Itasy-Ankarata volcanic field and bring them back to their lab for geochemical analysis. This analysis will tell them about the source of the lavas and how long ago they were expelled, giving them clues about how often the volcanoes have erupted historically.
In the summer of 2017, they will collect lava samples on the island of Nosy Be off the northwest coast of the island of Madagascar. While Nosy Be is less populated than the area around the Itasy-Ankaratra volcanic field, it is Madagascar’s most popular tourist destination.
Although Widom and Rasoazanamparany’s work may have practical implications for the people living in Madagascar, it will also help provide insights about basic volcanic processes.
According to Rasoazanamparany, Madagascar is key to understanding the break-up of the landmass Gondwana. A so-called supercontinent, Gondwana covered a large area of the southern hemisphere from approximately 300 to 180 million years ago. It included most of the landmasses in the modern southern hemisphere, including South America, Africa, and Australia.
“Before the breakup of Gondwana,” Rasoazanamparany says, “Madagascar was in its center. Part of Madagascar was connected to Africa and the other was connected to India. It broke off from Africa around 160 million years ago and around 90 or 80 million years ago, it started to separate from India. That separation coincided with extensive magmatism,” or flow of molten material emerging from beneath the earth’s crust.
As a result, Widom says, “Madagascar is a particularly interesting area to study to understand deep earth processes and their link to present day volcanism much, much later – millions, and maybe even a billion, years later.”
Some geologists theorize that during its break-up with India, Madagascar passed over a mantle plume – a column of hot, rising mantle possibly transmitted from the earth’s core-mantle boundary – that caused volcanoes to form. But because the still-active Itasy-Ankaratra volcanic field is very far away from any known plume, other geologists have speculated that Madagascar’s volcanism results from the melting of ancient mantle Madagascar took with it when it separated from Africa.
Regardless of whether Widom and Rasoazanamparany ’s work helps settle this debate, there’s little question it will contribute to a better understanding of Madagascar’s natural history. It may even help save the lives of people living within reach of its volcanoes. On this, Widom gives Rasoazanamparany much of the credit.
“We wrote the NSF proposal together,” Widom says, “but it was Fara’s idea initially that we work in Madagascar, and that we apply the kinds of techniques we have been using in other parts of the world to her home country.”
For her part, Rasoazanamparany says it’s exciting to be able to give back to the nation and the people she loves. Surely the feeling is mutual.
Written by Heather Beattey Johnston, Associate Director & Information Coordinator, Office for the Advancement of Research & Scholarship, Miami University.
Photos courtesy of Elisabeth Widom.