Figure 4From: Homemade ashmeter: a low-cost, high-efficiency solution to improve tephra field-data collection for contemporary explosive eruptionsA) Photograph and B) Sketch of the ashmeter. 1) Outer container; 2) funnel; 3) inner gauge; 4) cap filter. Note the slope of the funnel (> 35°) and the relationship between the size of the small bottle and the funnel lower aperture.Back to article page