Earthquake lights: Sakurajima Volcano, Japan -2011. Blaze of light and smaller floating balls of lights shooting out of the earth.
They are not UFOs. There is an article in National Geographic that points towards the electric nature of this atmospheric phenomenon:
Rare flashes of light that are sometimes seen around earthquakes are not caused by birds, or planes, or UFOs—all of which had been previously used to explain the phenomena known as earthquake lights.
Instead, the lights are caused by electrical properties of certain rocks in specific settings, report scientists in a new paper.
Sometimes called earthquake lightning, the lights can take “many different shapes, forms, and colors,” says study coauthor Friedemann Freund, an adjunct professor of physics at San Jose State University and a senior researcher at NASA’s Ames Research Center.Freund says common forms of earthquake lights include bluish flames that appear to come out of the ground at ankle height; orbs of light called ball lightning that float in the air for tens of seconds or even minutes; and quick flashes of bright light that resemble regular lightning strikes, except they come out of the ground instead of the sky and can stretch up to 650 feet (200 meters).
See also Electric Earthquakes.