It started last Mother's Day.
On May 12, the biggest volcano in the world started to swell. After 18 years of slumber, Mauna Loa was awake.
That same day, the Big Island's youngest and most active volcano, Kilauea, stepped up an eruption that has flowed nearly continuously since 1983. As the towering Mauna Loa grew, its smaller sibling spewed copious amounts of lava -- 30 times more than normal -- from two new vents torn from its flank.
The odd confluence of events did not go unnoticed. Now, after months of analyzing the behavior of the neighboring volcanoes, two geophysicists at the Hawaiian Volcano Observatory say the two volcanoes -- long seen as solo acts -- might be closely linked, or at the very least, might somehow commune with each other beneath the surface.
"This came as a surprise to us," said Peter Cervelli, an observatory geophysicist who with colleague Asta Miklius described the finding in today's issue of the journal Nature. "We're talking about conversations between volcanoes."
The analysis of the two volcanoes marks a success in using advanced technology to capture detailed, virtual, real-time information about the shuddering and creaking of volcanoes that are preparing to erupt.
While the vocanoes' deep, complex plumbing remains far beneath scientists' reach, their measurements of subtle changes at the surface is offering a better glimpse of what is happening below. The goal is to one day predict when, where and how these erratic beasts will erupt.
With Mauna Loa swelling and swarms of volcano-related earthquakes keeping residents on edge, the issue is more pertinent than ever. During the volcano's last eruption, in 1984, fast-moving lava came within four miles of Hilo, a harbor town with a population today of more than 40,000. The hefty volcano is considered the biggest volcanic threat on the island.
"Virtually the entire island is in Mauna Loa's potential flow area," said Cervelli. "It's a big mountain and not much is out of its reach."
Cervelli, a 35-year-old geologist who earned his doctorate last year at Stanford University, is part of a new generation of volcanologists using satellites, round-the-clock electronic monitoring and sophisticated tiltmeters originally developed for missile guidance systems to study the behavior of volcanoes.
The tilts and swellings -- sometimes just millimeters of movement -- are key to the magma and gases churning and bubbling up from below.
Unlike his predecessors who had to cut their way through jungles hauling heavy equipment to take single measurements of volcano deformation, Cervelli and his colleagues now get streams of nearly real-time data sent directly to their computers from global positioning satellite stations and electronic tiltmeters installed around both volcanoes. They can see a volcano's every breath. When a volcano starts to act up, they receive automatic e-mail alarms.
"I'm a little envious," said Don Swanson, the chief scientist at the observatory, who spent decades clambering up the flanks of Mt. St. Helens and Mauna Loa with monitoring equipment. "You can't compare. Real-time information is superior to anything we were doing 30 years ago."
Swanson, who hikes out to Kilauea's flowing orange lava every morning at sunrise in order to write a daily eruption update, knows these volcanoes better than anyone. He is among many scientists who do not believe the volcanoes, with summits that lie just 21 miles apart, are linked.
There is a lot of evidence on Swanson's side. The lava of the two volcanoes is entirely different. The volcanoes erupt in different patterns: Mauna Loa alternately from its summit and flanks and Kilauea more often from its flanks.
But Swanson isn't ruling anything out. Like many, he's long noticed a curious pattern. Through much of the past 150 years of recorded history, when one volcano flowed, the other was quiet, suggesting a possible negative relationship.
In theory, volcanoes should swell with magma until they erupt. Then they should deflate after the eruption empties out their magma chambers. Mauna Loa must be reading the wrong textbook. It inflated until its 1984 eruption and then stunned scientists by continuing to expand, Swanson said. In 1993, after years of steady swelling, it stopped, although there was no new eruption.
"How much inflation do you need before an eruption?" Cervelli said as he recently hiked to the Kilauea's fresh lava flow, stepping across rock so hot it could be felt through the soles of sturdy hiking boots. "We just don't know."
In recent months, geologists here have seen residents grow frightened by Mauna Loa's unrest. Despite the earthquake swarms and their heightened attention to every tic of the two volcanoes, the scientists here stress there is no reason for panic. To calm fears, Swanson and his crew have hosted several public forums and even traveled to housing developments to speak to those living in the path of potential lava flows.
"People have been scared needlessly," Cervelli said.
Though Mauna Loa and its lava could theoretically flood Hilo or fill the resorts of the island's Gold Coast with lava, about half of the eruptions of the 13,680-foot-high behemoth have stayed within its massive, isolated crater.
The very rumblings that frighten residents excite these geologists. Immediately after the inflation started, Cervelli borrowed several GPS stations from Stanford and flew them to the remote mountaintop.
If the volcano does erupt, Cervelli's instruments will capture every detail "from repose to eruption and then back to repose," he said. "This will be the first time that a Mauna Loa eruption is imaged with precise clarity." These eruptions are calmer bursts of relatively slow-moving lava, not explosive such as Mt. St. Helens' 1980 eruption in Washington state. Even without a full eruption to study, Cervelli has strong ideas about the relationship between the two volcanoes.
One possibility is that a pulse of magma rising to the surface was shared by both volcanoes through some linkage in their plumbing. More likely, he said, the pulse of magma filling Mauna Loa squeezed the neighboring, but distinct, Kilauea system and triggered the Mother's Day flow.
"One inflating could squeeze the other one," he said.
With more streams of data than he can handle, Cervelli is confident answers will begin flowing soon.
"The whole state of the art has changed during this one eruption," Cervelli said. "We are now seeing things we've never had an opportunity to see before in rich detail."