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Table 1 First data collected with the ashmeter network at Tungurahua volcano (from January 14 to March 16, 2012)

From: Homemade ashmeter: a low-cost, high-efficiency solution to improve tephra field-data collection for contemporary explosive eruptions

 

Location

 

CAH

CHO

JUI

OVT

PAL

PIL

RUN

Thickness

Reading (mm)

T

0,65

1

< 0,3

< 0,3

< 0,3

1,1

< 0,3

Absolute resolution (mm)

RA(T)

0,05

0,05

-

-

-

0,1

-

Relative resolution (%)

RR(T) = RA(T)/T

7,7%

5,0%

-

-

-

9,1%

-

Ash weight ( in situ )

Value (g)

M3 = M2 - M1

17,5

34,2

4,0

0,8

1,8

35,6

7,6

Absolute resolution (g)

RA(M3) = √(RA(M1)2 + RA(M2)2)

0,14

0,14

0,14

0,14

0,14

0,14

0,14

Relative resolution (%)

RR(M3) = RA(M3)/M3

0,8%

0,4%

3,5%

17,7%

7,9%

0,4%

1,9%

Area density ( in situ )

Value (g/m 2 )

ρ A(is) = M3/A

818,4

1599,5

187,1

37,4

84,2

1665,0

355,4

Absolute resolution (g/m2)

RA(ρA(is)) = ρA(is)*RR(ρA(is))

9,7

15,3

6,8

6,6

6,7

15,8

7,3

Relative resolution (%)

RR(ρA(is)) = √(RR(M3)2 + RR(A)2)

1,2%

1,0%

3,6%

17,7%

7,9%

0,9%

2,0%

Bulk density ( in situ )

Value (kg/m 3 )

ρ B(is) = ρ A(is) /T

1259,1

1599,5

-

-

-

1513,6

-

Absolute resolution (kg/m3)

RA(ρB(is)) = ρB(is)*RR(ρB(is))

98,0

81,4

-

-

-

138,3

-

Relative resolution (%)

RR(ρB(is)) = √(RR(ρA(is)2 + RR(T)2)

7,8%

5,1%

-

-

-

9,1%

-

Ash weight (dry)

Value (g)

M6 = M5 - M4

16,5

27,7

3,3

0,7

0,5

34,1

5,8

Absolute resolution (g)

RA(M6) = √(RA(M4)2 + RA(M5)2)

0,14

0,14

0,14

0,14

0,14

0,14

0,14

Relative resolution (%)

RR(M6) = RA(M6)/M6

0,9%

0,5%

4,3%

20,2%

28,3%

0,4%

2,4%

Area density (dry)

Value (g/m 2 )

ρ A(D) = M6/A

771,7

1295,5

154,3

32,7

23,4

1594,8

271,3

Absolute resolution (g/m2)

RA(ρA(D)) = ρA(D)*RR(ρA(D))

9,4

13,0

6,7

6,6

6,6

15,2

7,0

Relative resolution (%)

RR(ρA(D)) = √(RR(M6)2 + RR(A)2)

1,2%

1,0%

4,4%

20,2%

28,3%

1,0%

2,6%

Bulk density (dry)

Value (kg/m 3 )

ρ B(D) = ρ A(D) /T

1187,2

1295,5

-

-

-

1449,8

-

Absolute resolution (kg/m3)

RA(ρB(D)) = ρB(D)*RR(ρB(D))

93,5

67,2

-

-

-

133,2

-

Relative resolution (%)

RR(ρB(D)) = √(RR(ρA(D)2 + RR(T)2)

7,9%

5,2%

-

-

-

9,2%

-

  1. First data collected with the ashmeter network at Tungurahua volcano (From January 14 to March 16, 2012). CAH: Cahuají; CHO: Choglontus; JUI: Juive Grande; OVT: Observatorio del Volcán Tungurahua; PAL: Palitahua; PIL: Pillate; RUN: Runtun; A: Accumulation area; T: Thickness reading; M1: mass of inner gauge; M2: mass of inner gauge + in situ tephra load; M3: mass of in situ tephra; M4: mass of the receptacle used in laboratory; M5: mass of the receptacle + dry tephra load; M6: mass of dry tephra; ρA(is): In situ area density; ρ A(D) : Dry area density; ρ B(is) : In situ bulk density; ρ B(D) : Dry bulk density; R A : Absolute resolution; R R : Relative resolution. The ashmeters installed at this time (first generation) had a range of 0.3 – 10 mm and a resolution for thickness readings twice lower than the current model (fifth generation) used for the resolution calculation presented in the Additional file2.