The more viscous lava is, the harder it is for gases within it to bubbleout.
熔岩的粘度越大，其中的气泡就越难释放。
2
The more viscous lava is, the harder it is for gases within it to bubbleout, so such lava has an explosive tendency.
岩浆越黏，其内部的气体想通过气泡冒出就越困难，所以这种岩浆有爆炸的倾向。
3
One is the composition of the lava. The more viscous lava is, the harder it is for gases within it to bubbleout, so such lava has an explosive tendency.