( Calderas ( ( ( ( ( ( are large ) , ) usually ) ( ( ( roughly circular ) depressions ) ( that ( form ( by collapse ) ) ) ) ) ( over ( ( shallow ( magma chambers ) ) ( that ( have ( been ( partially ( emptied ( by ( volcanic eruptions ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Calderas)) (VP (VBP are) (ADJP (JJ large)) (, ,) (ADVP (RB usually)) (ADJP (NP (QP (RB roughly) (CD circular)) (NNS depressions)) (SBAR (IN that) (S (VP (NN form) (PP (IN by) (NP (NN collapse))))))) (PP (IN over) (NP (NP (JJ shallow) (NN magma) (NNS chambers)) (SBAR (WHNP (WDT that)) (S (VP (VBP have) (VP (VBN been) (VP (ADVP (RB partially)) (VBN emptied) (PP (IN by) (NP (JJ volcanic) (NNS eruptions))))))))))) (. .)))
Calderas are large, usually roughly circular depressions that form by collapse over shallow magma chambers that have been partially emptied by volcanic eruptions.
(ROOT (S (PP (IN After) (NP (DT a) (JJ massive) (NN eruption))) (, ,) (NP (NP (DT a) (NN mountain)) (VP (VBG collapsing) (PP (IN above) (NP (DT an) (JJ empty) (NN chamber))))) (VP (MD will) (VP (VB create) (NP (DT a) (NN caldera)))) (. .)))