About

Volcanic ash is not smoke; it is pulverized rock and glass with a melting point lower than the operating temperature of jet engines. When ingested, it melts and coats turbine blades, causing engine failure. This simulator models the advection-diffusion process of an ash plume. By correlating the Eruption Column Height with atmospheric wind vectors, we approximate the "Danger Zone" - the area where ash concentration remains high enough to threaten airspace.

The dispersion mechanics rely on the settling velocity of silicate particles. Heavy tephra falls near the vent, while aerosols (under 10 micrometers) can remain suspended in the Stratosphere for weeks, encircling the globe. This tool calculates the maximum drift distance before particles settle to the ground or disperse below critical concentrations.

Formulas

The horizontal drift distance D is a function of wind speed v_w and the particle residence time t_r.

D ≈ v_w × Hv_t

The terminal settling velocity v_t for fine ash is derived from Stokes' Law:

v_t = g ⋅ d² ⋅ (ρ_p − ρ_a)18 ⋅ μ

Where g is gravity, d is particle diameter, ρ_p is particle density (approx 2500 kg/m³), and μ is air viscosity.

Reference Data

Volcano	Year	VEI	Column Height (km)	Plume Reach (km)	Economic Impact	Region
Hunga Tonga	2022	5	58	Global	Submarine Cable Severed	Pacific
Eyjafjallajökull	2010	4	9	3,000	$5 Billion (Aviation)	Iceland/Europe
Pinatubo	1991	6	35	8,500	Global Cooling (-0.5°C)	Philippines
Mt. St. Helens	1980	5	24	2,500	$1.1 Billion	USA
Krakatoa	1883	6	80	Global	Global Temp Drop	Indonesia
Tambora	1815	7	43	Global	Year Without Summer	Indonesia
Novarupta	1912	6	30	4,000	Ash in Canada	Alaska
Ruiz	1985	3	8	150	Lahars (Tragedy)	Colombia
Chaitén	2008	4	19	1,000	Flight Cancellations	Chile
Redoubt	1989	3	12	800	747 Engine Failure	Alaska
Galunggung	1982	4	15	1,200	747 Glided to Jakarta	Indonesia
El Chichón	1982	5	32	Global	Climate Impact	Mexico
Soufrière Hills	1995	3	10	300	Island Evacuation	Montserrat
Vesuvius	79	5	32	500	Pompeii Destroyed	Italy
Etna	2021	2	5	50	Airport Closure	Sicily
Merapi	2010	4	12	600	Evacuations	Indonesia
Taal	2020	4	15	200	Manila Shutdown	Philippines

Frequently Asked Questions

Volcanic Ash Advisory Centers (VAAC) are nine organizations worldwide responsible for monitoring volcanic clouds and issuing warnings to the aviation industry.

Wind shear can transport ash in different directions at different altitudes. A plume might travel East at 5km altitude but West at 15km altitude.

In large eruptions, the plume rises until its density matches the surrounding air (neutral buoyancy), then spreads laterally, forming an umbrella shape.

This is a first-order approximation. Real-world dispersion involves complex turbulence, humidity (rainout), and varying wind layers which require supercomputer modeling.

Aviation authorities generally consider concentrations above 2 milligrams per cubic meter to be a "No Fly" zone, though engines can sustain damage at lower levels over time.