Seismica

Hidden fault lines run through the world, seeded with the world itself. Most of the time they stay silent, but stress builds until a rupture tears along the fault and sends two kinds of seismic waves outward at their own speeds. A quick jolt from the fast P-wave comes first, and then the slower S-wave, which does more harm, arrives and makes the terrain begin to break apart.

Magnitude follows the Gutenberg–Richter law, so small quakes are common and monsters are rare. Shaking attenuates with distance and depth, graded on the Modified Mercalli scale, so a distant M8 barely rattles a player while a shallow quake directly beneath them affects everything nearby. Foreshocks can warn of a larger event, and aftershocks follow a decaying sequence that is always weaker than the mainshock.

The mod runs on Forge and NeoForge for 1.20.1 and 1.21.1, and both the server and every player need it, because the environment is client and server. Each client works out the shaking on its own from seismic values that the server shares, so the network is not flooded with traffic. Seismica is released under the MIT License and is not open source. Its latest files are 1.7.0 for each loader, dated 2026-08-23.