| Atlin Volcanic Field(expression, name, volcano, geology) |
| Atlixcos(noun, name, volcano, geology) |
| Atuel(noun, name, volcano, geology) |
| Auckland Field(expression, name, volcano, geology) |
| Augustine(noun, name, volcano, geology) |
| Auquihuato(noun, name, volcano, geology) |
| Avachinsky(noun, name, volcano, geology) |
| Awu(noun, name, volcano, geology) |
| Axial Seamount(expression, name, volcano, geology) |
| Ayelu(noun, name, volcano, geology) |
| Azas Plateau(expression, name, volcano, geology) |
| Azufral(noun, name, volcano, geology) |
| Azufre(noun, name, volcano, geology) |
| Azul(noun, name, volcano, geology) |
| Azumayama(noun, name, volcano, geology) |
| Babuyan Claro(expression, name, volcano, geology) |
| Bachelor(noun, name, volcano, geology) |
| Bagana(noun, name, volcano, geology) |
| Bakening(noun, name, volcano, geology) |
| Baker(noun, name, volcano, geology) |