How do you know when a volcano erupts?

Answer 1

You can tell if a volcano's gonna erupt when you hear a low rumbling sound coming from the direction where the volcano is. The volcano will also start smoking (no, not a cigarette) about one hour beforehand. When it starts raining little balls of hot ash and billowing out pitch black smoke.... RUN!

Answer 2

Physical location in the surrounding geology & geomorphology (with allowances for continentral drift and erosion after deposition).#

Crystal structure: solidified lava crystals are generally very small thanks to rapid cooling.

The presence of vesicles (gas bubbles). (The walls of many of the old buildings in the City of Exeter were built from a mixture of Triassic conglomerate and a grey, highly-vesicular, fine-grained Hercynian-orogenic lava; both local rocks.)

Physical texture - is it homegenous or heavily inhomogenous, clastic, rubbly, etc?

Surface texture: Rubbly? Strongly-rippled (ropey) surfaces having solidified in air, with no confining rock to mould it?

If the underside is visible: inclusions of existing land surface material, but don't confuse with xenoliths in intrusive rocks.

Answer 3

Igneous rocks often contain grains that can be seen with the unaided eye.

Some igneous rocks have no visible grain and appear glassy

they show colored rains that are not in bands

Answer 4

There are different types of volcanic stones. For example: Granite, Felsite, Basalt, Feldspar, and Gabbro. This is a very helpful site: www.nativetech.org/stone/stonetypes/volcanic.html

Answer 5

When the ground starts to shake you here cracking and banging noises smoke comes out of the volcano and I you stand there to long you will be melted by the lava

Answer 6

you'll know when a volcano is erupting when. it starts shaking or when is starts getting hot

Answer 7

Volcanic ejecta are "foamy". They tend to have evidence of gas pockets. Also, rock which forms from slow cooling magma have larger crystals. Ejecta have crystals that are microscopic.