Lava flows from Hawaii's Kilauea volcano threaten to force residents on the state's biggest island to evacuate after advancing more than 250 yards over the weekend. Lava continued to move at around 10 to 15 yards per hour on Monday morning.

There were about 50 to 60 structures at risk, according to Darryl Oliveira, director of civil defense for Hawaii County. Those include homes and businesses, the closest of which is about 300 yards ahead of the flow front. Authorities told residents to be prepared to evacuate by Tuesday. Some residents reported they could see the flow front from their balconies, Oliveira said.

Lava hit a largely Buddhist cemetery in Pahoa, a town of about 1,000 people around 17 miles south of Hilo, the largest city on the island. A Sunday night update from the U.S. Geological Survey’s Hawaiian Volcano Observatory said the flow split into two fingers on Saturday. The northern lobe of the flow has completely passed through the cemetery, while the southern lobe is moving through a field. The flow is about a half mile away from Pahoa’s main road. Aerial photos of the flow’s advance can be seen here.

Hawaii Governor Neil Abercrombie has asked for President Barack Obama to declare a federal disaster, which would make certain federal emergency funds and resources available to Hawaiian authorities. Abercrombie declared a state of emergency on the Big Island last month. The Red Cross established a shelter in the area for evacuees, but the Associated Press said most people at risk in the area are prepared to evacuate and have a place to stay, whether it be with family or friends. 

Kilauea is "among the world's most active volcanoes and may even top the list," according to the USGS. It's the youngest on the Big Island. It's Hawaiian name appropriately means "spewing" or "much spreading."