Table 5 Summary of the most common terms in the ‘tephra form’ and ‘content’ columns in the ‘Layers’ tab of the database.

Content\Form	Layer	Patch	Mixed	Totals:	False + (sub-sample)	Yes (sub-sample)
Tephra	22,535	3,804	530	26,869	20% (182)	80% (726)
Tephra-rich	160	545	42	747	52% (13)	48% (12)
Tephra-bearing	4	0	5	9	N/A	N/A
Ashy	131	185	9	325	29% (2)	71% (5)
Tuffaceous	26	22	5,895	5,943	N/A	N/A
Vitric	17	3	8	28	13% (22)	87% (141)
Volcanic	46	21	62	129	13% (19)*	87% (124)*
Volcaniclastic	408	15	221	644	13% (19)*	87% (124)*
Totals:	23,327	4,595	6,772	34,696

The physical form of each tephra is listed as either a layer, patch or mixed. This is decided by the data collection team by using the information given on the VCD. A patch can also be described as: pod, pocket, lens, bleb, blob, spot, speck, glob. The descriptions given in the VCD also give an indication of the volcanic content of the tephra occurrence. The left hand column lists the main volcanic descriptive terms that were used to identify tephra occurrences. These terms can cover several variations, for example here ‘Tephra’ includes ‘tuff’ and ‘ash’. The two right hand columns relate to the content descriptors that were checked during ground truthing⁶, note that only a subset of the VOLCORE data (1,246 of 34,696 tephra occurrences) were ground truthed. Relative percentages of False positives and confirmed tephras are given, with actual numbers in parentheses. ‘False + ’ indicates over-recorded tephra, ‘Yes’ indicates correctly identified tephra. False negative numbers are not included, as by definition they were tephra occurrences that had not been recorded in a VCD, and so have no descriptive terms. *‘Volcanic’ and ‘Volcaniclastic’ have the ground truthing numbers for the term ‘Volc’.

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