PAHOA, HAWAII, May 20, 2018 (News Wires) – Lava oozing out of cracks for two weeks in rural Hawaii neighborhoods took on new characteristics as fresher magma mixed with decades-old magma, sending a flow towards the ocean Saturday. The first known serious injury in the eruptions was reported on Saturday. "A homeowner on Noni Farms Road who was sitting on a third-floor balcony got hit with lava spatter," said Janet Snyder, a spokesperson for the Office of the Mayor, County of Hawaii. "It hit him on the shin and shattered everything there down on his leg," she said, adding that lava spatters "can weigh as much as a refrigerator and even small pieces of spatter can kill." No other information was immediately available. Since a first fissure opened in a community on May 3, lava was mostly spattering up and collecting at the edges of the cracks in the ground. Two neighborhoods with nearly 2,000 people were forced to evacuate as lava claimed 40 structures. On Friday afternoon, the lava changed dramatically, with one fissure ramping up and sending a flow across a road, destroying four more homes and isolating residents, some of whom had to be airlifted to safety. The change is attributed to new magma mixing with 1955-era magma in the ground, creating hotter and more fluid flows, scientists said. "There's much more stuff coming out of the ground and it's going to produce flows that move further away," said Wendy Stovall, a U.S. Geological Survey volcanologist. By Saturday morning, two of 22 fissures had merged, creating a wide flow advancing at rates of up to 300 yards (274 meters) per hour. Aerial footage from the USGS showed fast-moving lava advancing to the southeast. The flow was 1.5 miles (2.4 kilometers) from the ocean, scientists said. In the background, the footage showed lava fountaining 328 feet (100 meters) high at one of the fissures. The fountains are created by vents closing, forcing magma to burst through a single outpoint, Stovall said. If lava threatens main highways, more people will be told to prepare for voluntary evacuation. A lava flow was less than a mile (kilometer) away from Highway 137 and would reach it in a matter of hours, officials warned Saturday afternoon. No one lives in its path and another highway remained open as an escape route, said Hawaii County spokeswoman Janet Snyder.