Researchers at the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science analysed the seismic waves that travel through the volcano to understand the internal structure of the volcanic system.
Using the seismic data, the researchers developed a three-dimensional velocity model of a magma anomaly to determine the size, depth and composition of the lava chamber, which is several kilometres in diameter and located at a depth of 8-11 km.
"It was known before that Kilauea had small, shallow magma chambers," said Guoqing Lin, UM Rosenstiel School assistant professor of geology and geophysics and lead author of the study.
"This study is the first geophysical observation that large magma chambers exist in the deep oceanic crust below," Lin said in a statement.
The study also showed that the deep chamber is composed of "magma mush," a mixture of 10-per cent magma and 90-per cent rock.
The crustal magma reservoir below Kilauea is similar to those widely observed beneath volcanoes located at mid-ocean ridges, researchers said.
"Understanding these magma bodies are a high priority because of the hazard posed by the volcano," said Falk Amelung, co-author and professor of geology and geophysics at the UM Rosenstiel School.
"Kilauea volcano produces many small earthquakes and paying particular attention to new seismic activity near this body will help us to better understand where future lava eruptions will come from," Amelung said.
Kilauea, believed to be 300,000 to 600,000 years old, has been in continuous eruption for more than 30 years, making it the most active volcano in the world.