EXCLUSIVE: Pinay scientist details discovery of 'largest caldera' Apolaki in Benham Rise

Jenny Anne Barretto was looking at a detailed map of Benham Rise at the GNS Science Institute in New Zealand.

From the shaded relief map, the Pinay marine geophysicist could see the various features of the continental shelf, which was shaped by volcanic activity in the past.

But something in the map caught her eye: a huge volcanic feature that piqued her curiosity.

"The first time I recognized that it looked like a caldera, I sank into my chair. The size, the sheer, enormous size of the caldera, made me sink. It's huge. It’s [diameter was] 150 kilometers wide," she said in an exclusive interview with GMA News Online, as she described her awe when she realized that the crater-like feature she saw on the printed map could be the largest caldera in the entire world.

This particular caldera in Benham Rise, which was named 'Apolaki', exceeded the dimensions of the Yellowstone Caldera in the US and other large calderas in other countries.

The Apolaki caldera's size was similar to that of shield calderas such as Olympus Mons on Mars (80 km x 65 km) and Sacajawea on Venus (150 km x 105 km).

A caldera is a large basin-shaped volcanic depression, caused by the collapse of the ground when large volumes of magma are expelled from a volcano's magma reservoir, according to the US Geological Survey (USGS).

‘Just the beginning’

Barretto's discovery of the Apolaki caldera on Philippine territory is nothing short of groundbreaking, but that was just the beginning of four years of research.

She knew she had to work on an explanation for how the Apolaki caldera formed, so she enlisted the help of veteran scientists Ray Wood and John Milsom.

Together, they analyzed multibeam bathymetry data from the National Mapping and Resource Information (NAMRIA), gravity data, magnetic data and the published geochemical analysis of rocks found on Benham Rise.

What's interesting about Barretto and her team's explanation behind Apolaki is that they did not have to set foot on Benham Rise to see if the caldera existed.

"Everything was done on desktop. There was no field work. There was no survey, because the bathymetry survey was already [done] by NAMRIA," she said, explaining that they solely relied on maps and other publicly-available data in her team's research.

Aside from explaining how the Apolaki caldera was formed, Barretto and her team were able to describe the morphological features of the Benham Rise for the first time.

It was a feat that no other research team has uncovered.

In their scientific paper, the team wrote that the Benham Rise crest exhibited a caldera morphology, as the Benham Rise was shaped by volcanic activity in its early stages.

"Features like a breached rim, intra-caldera benches, and a resurgent dome indicate a multi -phase volcanic history consisting of both quiet and explosive eruptions," the team wrote in their scientific paper.

Pinoy pride

For the New Zealand-based scientist, whether it was a big or small caldera, the discovery was always exciting and significant.

"But we are also aware that it is possible, any time in the future, another scientist will be able to discover something else, or sort of refute what you have discovered and say, 'No, this is not the biggest one' or 'No, it doesn't look like a caldera to us'. It's fine, because that is how science works. And we're open to that," she said.

She added that her team's paper underwent two rounds of peer review by other geoscientists.

Passing a peer review meant that other scientists approved of the paper's findings and interpretations.

For Barretto, the discovery of the Apolaki caldera in Philippine territory is something that Filipinos should be proud of.

"It's significant because we pride ourselves on holding records for almost anything. Being able to recognize the largest caldera ever on earth - and it's just in our backyard - [is] something significant. It's something to be proud of," Barretto said.

Barretto, who took her undergraduate studies at the National Institute of Geological Sciences from the University of the Philippines Diliman, hopes that her team's research would spark interest in the youth to pursue the sciences. —JST, GMA News