During an eruption:

* In the air: During an eruption, volcanic ash is ejected into the atmosphere and can travel vast distances, depending on the eruption's strength and wind direction.

* Around the volcano: Ash falls heavily in the immediate vicinity of the volcano, creating a thick layer on the ground.

After an eruption:

* On the ground: Ash settles on the ground, forming layers that can vary in thickness depending on the distance from the volcano and the intensity of the eruption.

* In water bodies: Ash can fall into lakes, rivers, and oceans, creating sediment layers.

* In ice cores: Volcanic ash can be trapped in layers of ice, providing scientists with a record of past volcanic activity.

* In archaeological sites: Ash layers can provide evidence of past volcanic eruptions, giving insights into ancient civilizations and their interactions with volcanic hazards.

Other locations:

* In museums and research institutions: Samples of volcanic ash are collected and studied by scientists to understand volcanic processes and history.

* In building materials: Volcanic ash can be used in construction materials like concrete and cement.

It's important to remember that volcanic ash can pose significant risks to human health, infrastructure, and the environment, and its presence should be treated with caution.