In which paragraph does the author elaborate what imposes low or high explosion of a volcano?

The Distinction of Magma and Lava

Hawaii’s Kilauea volcano keeps erupting with syrupy lava flows, serving as a fiery reminder of nature’s destructive power. There are two contents flow out as molten rock and they both have to do with volcanoes. But as the ongoing eruption captures headlines, a question might occur to the readers: What’s the difference between magma and lava?

The distinction between magma and lava is all about location. When geologists refer to magma, they’re talking about molten rock that’s still trapped underground. If this molten rock makes it to the surface and keeps flowing like a liquid, it’s called lava. Lava is molten rock generated by geothermal energy and expelled through fractures in planetary crust or in an eruption, usually at temperatures from 700 to 1,200 °C (1,292 to 2,192 °F). The structures resulting from subsequent solidification and cooling are also sometimes described as lava. The molten rock is formed in the interior of some planets, including Earth, and some of their satellites, though such material located below the crust is referred to by other terms.

Magmas vary in their chemical composition, which gives them—and the volcanoes that contain them—different properties. Mafic magmas like those in Hawaii tend to form when the heavier crust that forms the ocean floor melts. They contain between 47 to 63 percent silica, the mineral that makes up glass and quartz. Silicic magmas, on the other hand, tend to form when the lighter continental crust melts. These magmas are more than 63 percent silica, which makes them more viscous: At their runniest, silicic magmas flow about as well as lard orcaulk—which is to say not well at all. They’re also cooler than mafic magmas. Rhyolite, an especially silica-rich type of lava, hits temperatures between only 1,200 degrees to 1,500 degrees Fahrenheit.

When silicic magmas are no longer confined under sufficiently high pressure, the gases dissolved within them come out of solution and form bubbles. And just like opening a shaken-up can of soda, the resulting rush of vapor triggers an explosive eruption. Iconic cone-shaped volcanoes called stratovolcanoes, such as Mount Pinatubo, are loaded with silicic magmas. Hawaii’s volcanoes, on the other hand, contain especially low-silica magmas made of basalt, which means they have much less explosive oomph. Instead, they ooze and spatter, creating shield volcanoes—gently sloped formations that have become the islands’ signature geologic silhouette.