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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.