Modifiers matching depression:

• chronic,
• mental,
• major,
• clinical,
• severe,
• volcanic,
• topographic,
• geriatric,
• moist,
• regular,

Simple categories matching volcanic:

• material,
• stratum,
• phenomenon,
• depression,
• rock,
• centre,
• emanation,
• deposit,
• unit,
• feature,
• event,
• condition,
• structure,
• form,
• action,
• process,
• formation,
• lava,
• mineral,
• flow,
• system,
• substrate,
• marker,
• activity,
• product,
• domain,
• sand,
• cone,
• sediment,
• hazard,
• component,
• substance,
• stone,
• island,
• precursor,
• episode,
• eruption,