Volcanic Eruptions
Describe Pyrocalstic Materials and Lava
What is Pyroclastic Material ?
Types of pyroclastic material
Volcanic Ash and Dust
Volcanic Ash is less than 2 mm in diameter . On the other hand , volcanic dust is less than 0.25 mm in diameter . They both usually settle on the land and immediately surround the volcano . Some dust particles travel around earth into the upper atmosphere .
Lapilli
Lapilli is less than 64 mm in diameter . The word 'lapilli' comes from a Latin word which means "little stones" . They usually fall near the vent .
Volcanic Bombs and Blocks
Volcanic bombs are larger than 64 mm in diameter . When they are thrown out the volcano , it cools down and forms into a round or spindle shape . Volcanic Blocks are 2.5 inches in diameter . It is the largest pyroclastic material . Some are as large as small houses .
What Are The Types Of Mafic Lava ?
Pahoehoe Lava
The pahoehoe lava is the least viscous type . It forms into a wrinkly volcanic rock . Pahoehoe actually means "ropy" in Hawaiian .
aa lava
aa lava is more viscous than pahoehoe lava and forms sharp volcanic rock when it cools.
Blocky Lava
The blocky lava is the most viscous . It forms into a chunky volcanic rock . It has a higher silica content than the Aa lava . Since the lava is thick it doesn't travel far from the volcanoes vent .