This simulation models a volcanic eruption as a 2D cross-section, using a particle pool of up to 3,000 ejecta. Each particle is tagged as a lava bomb, ash grain, gas puff, or pyroclastic flow, and is advanced each frame under gravity (0.18) plus type-specific forces. Pressure accumulates in the magma chamber and, once it reaches 100, the vent erupts, launching particles up through the crater at velocities set by the eruptive force.
The control panel lets you pick an eruption style (Strombolian, Hawaiian, Vulcanian, or Plinian) and tune four parameters: pressure rate, eruptive force, lava viscosity, and ash density. Higher viscosity slows lava flow on the flanks, while ash density governs the plume. Live readouts report particle count, lava temperature, an approximate Volcanic Explosivity Index (VEI), and eruption tally — illustrating how magma composition shapes real eruptions, from gentle lava fountains to deadly pyroclastic surges.
What does this volcano simulation actually show?
It shows a side-on cross-section of a volcanic cone with a central vent. Magma pressure builds in the chamber, and when it erupts the vent throws out lava bombs, an ash plume, gas, and pyroclastic flows. Each piece of ejecta is a separate particle moving under gravity and drag.
How does the eruption mechanism work?
Pressure rises every frame at a rate you set. When it reaches 100 the volcano auto-erupts, or you can trigger it manually with the Erupt button. During an eruption the vent spawns batches of particles for a duration scaled by the eruptive force, with velocities and counts drawn partly at random to mimic turbulent ejection.
What do the four sliders control?
Pressure rate sets how fast the chamber recharges between eruptions. Eruptive force sets the launch speed and how many lava bombs are flung out. Viscosity (0.1 to 1.0) controls how quickly lava decelerates and slides on the slope. Ash density (0 to 10) sets how many ash grains rise into the plume.
Strombolian gives frequent mild bursts of lava bombs; Hawaiian uses low-viscosity, free-flowing lava; Vulcanian is short, ash-rich and explosive; and Plinian is the most violent, with the highest force and a towering ash column. Each preset loads matching pressure, force, viscosity, and ash values.
Lava bombs follow a ballistic arc, then convert to a flowing pyroclastic particle on landing. Ash is buoyant (it loses half of gravity), drifts with a small wind force, and dies on impact. Gas rises strongly and fades. Pyroclastic flows hug the ground and slow down as they spread along the flanks.
The VEI is a logarithmic scale from 0 to 8 used by volcanologists to rank eruption magnitude by erupted volume and plume height. In this simulation it is a simple approximation derived from the eruptive force, so it is indicative rather than a calibrated measurement. Plinian-scale events sit at VEI 5 to 8.
Viscosity reflects magma chemistry: silica-rich magmas are stickier, trap gas, and erupt explosively, while runny basaltic magma flows freely as in Hawaiian eruptions. In the model, higher viscosity makes lava bombs and pyroclastic particles decelerate faster, so flows stay short and thick instead of racing down the slope.
The temperature readout maps the hottest active particle's internal heat value onto a range of roughly 700 to 1,100 degrees Celsius, which brackets real lava temperatures. Particles cool gradually each frame, so freshly ejected lava glows brightest and the colour shifts from white-orange towards dark red as it loses heat.
It is a qualitative, educational model rather than a research-grade fluid solver. It captures the right behaviours — ballistic bombs, buoyant ash, rising gas, ground-hugging pyroclastic flows, and the viscosity-explosivity link — but it does not solve real magma dynamics, thermodynamics, or atmospheric physics, and the numbers are illustrative.
It illustrates why pyroclastic flows are a volcano's deadliest threat: they move fast, hug the terrain, and stay hot. It also shows how an ash plume drifts downwind, which is why eruptions disrupt aviation and air quality far from the vent, and why eruption style depends heavily on magma viscosity and gas content.