Geologists and astrophysicists have joined in a fantastic scheme to create a 3-D image of the Earth's last frontier - its scalding, vast and impenetrable interior.
The subterranean imagery might help researchers better understand volcanoes and earthquakes, which are powered by the slow, relentless flow of hot magma beneath Earth's surface."It's like CAT-scanning the Earth," said UC-Berkeley geophysicist Barbara Romanowicz, one of numerous scientists connected with the imaginative scheme. The project was announced at the American Geophysical Union conference in San Francisco.
Researchers hope to develop an underwater observatory that would "see" stars and galaxies by looking through thousands of miles of solid rock toward the opposite side of Earth.
The technique would measure ghostly outer-space particles called neutrinos, which pass through Earth - an 8,000-mile-thick "ocean" of rock - like bullets through fog, say Berkeley scientists linked to the project.
The first step should take place when scientists begin dropping neutrino detectors into the ocean off the island of Hawaii.
These neutrino "telescopes" will be pointed at the ocean floor, not up at the sky like ordinary telescopes. Deep beneath the waves, the detectors will see subatomic particles called muons emerging from the ocean floor. The muons were created by neutrinos during their 8,000-mile journey from the planet's opposite side, as they interacted with matter en route.
The neutrinos come a long way - from explosive astronomical objects such as pulsars, which are thousands or millions of light-years away.
During the journey, neutrinos pass through areas of different density. Earth's core is so dense and hot that steel would flow like melted butter. The denser the region, the greater the chance it will interact with a neutrino, causing it to emit a muon.
By measuring variations in the intensity of muons, scientists hope to map density variations within Earth, a geological version of a doctor's X-ray.
Then, by pooling data from other neutrino detectors around the planet, scientists would create a three-dimensional image of Earth's innards. Other detectors are still in the development or talking stage, and include one deep within the Antarctic ice pack.
The UC-Berkeley geoscientists proposed the idea several years ago during conversations with researchers at the University of Hawaii, who were developing the Deep Underwater Muon and Neutrino Detector for astronomical reasons. By the end of the year the main array of detectors should be in place, covering roughly 100,000 cubic feet of ocean.
It's too early to say whether the device will be sensitive enough to make meaningful measurements, cautions UC-Berkeley geophysicist Raymond Jeanloz: "We might get a lot of (data) quickly, or it might prove to be so slow that it would take several centuries to gather the data."
Distributed by Scripps Howard News Service