whoa. ( laughs ) >> haraldur sigurdsson: yeah! >> pelley: oh, my god. >> sigurdsson: incredible.ou're looking right into the crater. >> pelley: scientists rate volcanic eruptions on a scale of zero to eight. this is a four, which they call "cataclysmic." tell me what you're seeing. >> sigurdsson: its an explosive eruption, and the explosions are producing big clouds of ash that are moving up straight up into the atmosphere at the velocity of a few hundred feet per second. and throwing out huge rocks. >> pelley: how big are these pieces that we see flying? >> sigurdsson: some of these are the size of cars. >> pelley: and how high are they going up? must be a thousand feet. >> sigurdsson: at least a thousand feet. but they're still red hot, maybe 2,000 degrees fahrenheit. >> pelley: what's causing these stupendous explosions that we're hearing? >> sigurdsson: well, the big booms that we're hearing are huge gas bubbles in the magma that are popping open. they may be 100 feet in diameter. and when they get closer to the surface, the pressure inside these gas bubbles is so great that

go no further we hiked with our guide, one of the world's leading authorities on volcanoes, haraldur sigurdssonis astounding. >> isn't it? >> whoa! look at that! oh, my god! >> incredible! what a sight! i'm looking right into the crater. >> reporter: scientists rate volcanic eruptions on a scale of 0 to 8. this is a 4 which they call "cataclysmic." tell me what you're seeing. >> it's an explosive eruption and explosions are producing big clouds of ash that are moving up, straight up into the atmosphere at the velocity of a few hundred feet per second and throwing out huge rocks. >> reporter: how big are the piece wes see flying? >> some of these are the size of cars. >> reporter: how high are they going up? it must be a thousand feet. >> at least a thousand feet but they're still red hot. they may be 2,000 degrees fahrenheit. >> reporter: unbelievable. >> dubois: and you can see scott's full report on volcanoes this sunday on "60 minutes." well, the second winner from last month's $648 million megamillions jackpot has come forward. he is steve tran of california. somehow he got around to checki