In the video below you will see a strange "green beam" captured from the Kyoto Live Cam at the Sakurajima volcano, this occurrence I put in the video lasts over 4 minutes, but some last a shorter period of time and some longer. Links to the live cam will be provided above the video.
Note- When you first open the Kyoto cam all you see is a black screen, but about every ten minutes, give or take a minute or two, these green laser-like beams appear and give of a little light show.
Some speculate the beam is coming from some type of laser in order to collect scientific data and research does show that lazer technology does exist exactly for that purpose, although I haven't found any official statement saying that is what this is.
Correction to video commentary- The email leading me to this live camera came last night, in the video I state it apparently started last night, but further research shows this has been happening since mid-May, at least, as Tweets found at the website Portal Mie, show images of this green beam from May 19 and 20th, both shown below. The Portal Mie website also asks if this isn't lasers.
In 2004, via O S A Publishing we see that "Laser spectroscopy enables online, in situ monitoring of volcanoes. In combination with fiber optic sensors, it may one day serve as the basis for a new type of eruption warning system," but there are no images showing whether this technology appears as a "green beam."
In December 2013, LiveScience published an article about lasers and lava flow and described how lasers are used to create 3D images of volcanic activity and lava flow, using planes equipped with thousands of lasers, but in none of the images seen so far, nor the tweet images shown above or the video, do we see any planes.... just the beam.
June 2015, via ResearchGate we see another article discussing the use of lasers to monitor volcano, again no images on the color or even if these lasers would manifest in appearance the way we see in the video below.
