Vulnerability of laptop computers to volcanic ash and gas

Abstract

Laptop computers are vital components of critical infrastructure sectors and a common tool in broader society. As they become more widely used, their exposure to volcanic hazards will increase. Therefore, understanding how laptops will function in volcanic environments is necessary to provide suitable mitigation options. In this study, laptop computers were subjected to volcanic ash and gas in both laboratory and field settings. None of the laptops sustained permanent damage in laboratory experiments; however, ash contamination did reduce the functionality of keyboards, CD drives, and cooling fans. Several laptops shut down temporarily due to overheating following ash contamination. In field experiments, laptops were exposed to high concentrations of volcanic gases at White Island, New Zealand. These laptops did not sustain permanent damage as only a small amount of gas was able to enter the laptops. However, metal components on the outside of the laptop did sustain minor corrosion. Re-examination of the laptops after 6 months indicated they were in full working order. Printed circuit boards suffered significant corrosion damage and ceased working only when in direct and sustained contact with volcanic gases. Simple mitigation techniques such as isolating laptops inside heavy duty polyethylene bags were effective. Overall, our experiments demonstrate that laptops have a relatively low risk of damage from volcanic ash and gas exposure, but have a low-medium risk of loss of functionality in ash environments. We think this has implications for other electronic equipment used extensively in critical infrastructure services.

Appendix

1.1 Characterization of basaltic pseudo ash

To conduct volcanic ash vulnerability experiments in the laboratory, large quantities of fresh volcanic ash were required. Fresh ash is coated in acidic soluble salts that can cause corrosion; however, these salts are rapidly leached from fresh ash deposits. Due to the logistical difficulties of obtaining large quantities of fresh volcanic ash, a basaltic pseudo ash was created. Basalt lava from the Lyttelton Volcanic Group was chosen as the base material as it is locally abundant and has similar chemical characteristics to volcanic ash. Blocks chosen were unweathered (to avoid contamination from any alteration products), fine-grained, and 15-40 cm in diameter and were obtained from the Gollans Bay Quarry in the Port Hills, Christchurch, New Zealand.

Once the blocks were cleaned with water, to remove any organic material, and dried, they were passed through three different machines (a hydraulic splitter, a jaw crusher, and a disk pulverizer) to produce particles <2 mm in diameter. Particles >1 mm tended to be tabular in shape due to fracturing along crystal boundaries and did not resemble the morphology of volcanic ash. To reduce the concentration of these particles, the ash was passed through a 1-mm aperture sieve before being stored in two sealed 45-L copolymer polypropylene storage bins.

To ensure the pseudo ash grain size was comparable to volcanic ash, the grain size was analyzed with a Partica LA-950 laser diffraction particle size analyzer at Massey University, Palmerston North, and compared to five volcanic ash samples (Fig. 13). The pseudo ash sits within the range of volcanic ash grain sizes; however, it contains slightly less fine-grained particles. The density of the pseudo ash was compared to five in situ ashes from the Taupo Volcanic Zone. The density of the pseudo ash was the second highest at 1,572 km/m³, due to its fine grain size and basaltic composition, which is generally denser than other volcanic rocks. SEM images of pseudo ash were taken and compared to Ruapehu 1995–96 volcanic ash (Online Resource 5). Pseudo ash particles tended to be blocky in nature with angular edges, which often intersected at right angles. The main difference between volcanic ash particles and the pseudo ash was that there was a lack of vesiculated surface morphology, typical of volcanic glass, in the pseudo ash samples.

Fig. 13

Grain size distribution comparison between pseudo ash and five volcanic ashes. Merapi and Montserrat ashes are from near vent sources (<10 km), were as Reboubt, Ruapehu, and Chaiten are from downwind sources (~100 km)

To replicate the soluble salt coating found on fresh volcanic ash, the crushed basalt particles were mixed with fluid (dosing solution) from Crater Lake, Mt. Ruapehu, New Zealand. Once dried, various soluble minerals precipitate onto the ash surface. A leachate study was undertaken to determine which ash to dosing solution ratio (1:1, 2:1, 4:1) best approximated fresh volcanic ash leachates.

A 30-g sample of pseudo ash was mixed with the appropriate amount of dosing solution, with respect to the dosing ratio, and left to dry at room temperature for 2 days. Once dry, 1.25 g of dosed ash was added to 50 mL of distilled water (1:40 ratio) and placed in an end-over-end mixer for 24 h. After mixing, samples were filtered using 0.2-μm syringe filters before being sent to the GNS Science Wairakei Analytical Laboratory for analysis. Cations were analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES) and anions by ion chromatography (bromide, fluoride, and sulfate), potentiometric method (chloride) and the methylene blue method (sulfide).

The ash leachate results are shown and compared to minimum, maximum, and average leachate values of volcanic ash in Table 3. When compared to leachate values from real volcanic ash, all dosing strengths are above minimum values but below average values. Sulfate (SO₄ ²⁻) is the most abundant species found in the pseudo ash leachates and is due to large concentrations in Crater Lake fluid. The concentration is high in this fluid because SO₄ ²⁻ is the stable end product of a number of dissolution and oxidation reactions that take place in the lake (Christenson and Wood 1993). The next most abundant species in the pseudo ash leachates are Cl, Ca, and Mg, respectively. Chloride and Mg concentrations for the 2:1 and 4:1 strength pseudo ash are above minimum concentrations when compared to real volcanic ash leachates, whereas the 1:1 strength is above average values. Chloride and Mg concentrations are elevated because Crater Lake fluid is enriched in these elements, as Cl derived from fumarolic steam, mainly as HCl, from fumaroles on the crater floor, and Mg is derived from the interaction of hot acidic water with fresh magmatic material (Giggenbach and Glover 1975).

Table 3 Concentrations of selected ions for three different dosed pseudo ashes compared to minimum, maximum, and average concentrations of ten volcanic ashes (Mount St. Helens Ash 1980; Fuego Ash 1973, 74; Pacaya Ash 1974; Santiaguito Ash 1967, 75; Ruapehu Ash 1995–96; Popocatepetl Ash 1994–96, 97, 98)

Fluoride appears in relatively low concentrations, with the 1:1 sample having concentrations higher than the minimum, but lower than the average, ash leachate concentrations, while the 2:1 and the 4:1 sample have lower concentrations. This is an important ion as it is the principal toxic element absorbed onto ash particles (Witham et al. 2005).

Overall, all the dosing solutions have similar correlation coefficients (0.88 for the 1:1 and 2:1 samples and 0.87 for the 4:1 sample) when compared to average volcanic ash leachate values. The 2:1 dosing ratio was selected for this research as it had a strong correlation and required less Mt. Ruapehu Crater Lake fluid, which was difficult to obtain in large quantities.