A new African sea Massie Santos Ballon Philippine Daily Inquirer
November 06, 2009
AMID THE STORIES OF DRY riverbeds, water shortages and droughts is an eye-catching story about the the formation of a new sea in a landlocked country.
Four years ago, tectonic shifts below the east African nation of Ethiopia triggered volcanic activity and began trying to split the continent. Over the course of a month in late 2005, more than 400 earthquakes, half of them with magnitude 3.6 or larger on the Richter scale, were centered on a rift roughly 60 kilometers long.
The rift is still growing, albeit very, very slowly. An international team of researchers led by Atalay Ayele of Ethiopia’s Addis Ababa University and England’s University of Leeds has now determined that the divide is actually the beginning of a sea.
Researchers are interested in the Ethiopian rift’s development because the movement of the tectonic plates mimics what goes on at the bottom of the world’s oceans, offering them a glimpse of what they haven’t been able to look at in person before.
“The whole point of this study is to learn whether what is happening in Ethiopia is like what is happening at the bottom of the ocean where it’s almost impossible for us to go,” said University of Rochester research and study coauthor Cindy Ebinger in a statement.
“We knew that if we could establish that, then Ethiopia would essentially be a unique and superb ocean-ridge laboratory for us.”
To understand what caused the rift in the first place, Ayele collected the 2005 seismic data from Ethiopia and its neighbor Eritrea and mapped the earthquakes in the region during the period. The analysis revealed that the 60-km rift’s cause was more violent than expected, the tectonic plates moving far more quickly than had been previously expected.
To get a visual idea of the speed and force applied, take a suitcase or bag with double zippers on a single strip. Place the zippers in the center and then pull them apart in opposite directions as quickly as possible.
“We know that sea floor ridges are created by a similar intrusion of magma into a rift, but we never knew that a huge length of the ridge could break open at once like this,” Ebingersaid. “Seafloor ridges are made up of sections, each of which can be hundreds of miles long. Because of this study, we now know that each one of those segments can tear open in a just a few days.”
If the rift opened as researchers had thought slowly and in small sections over time such changes would be less disruptive to the lives of those living in the affected areas. And at last check, Ethiopia’s population is slightly smaller than that of the Philippines by a few million people, though the African nation has three times the land mass at a million square kilometers or 10,000 hectares.
The presence of a sea in Ethiopia may prove beneficial, although it will take millenniums for the event to be completed. Right now, studies estimate that a tenth of Ethiopia is arable land, and less than two thirds of a percent of that land is used for food crops. In comparison, almost 20 percent of the land in the Philippines is arable, and nearly 20 percent of the land is allocated for permanent crops.
The study was published online Oct. 20 in the journal Geophysical Research Letters.
