Energy release scales very rapidly with moment magnitude: the radiated energy is proportional to 10^(1.5*M). That means each unit increase in magnitude boosts energy by about 10^1.5 ≈ 31.6. Going from Mw 4 to Mw 8 is four steps, so the factor is 10^(1.5×4) = 10^6, about a million. So an Mw 8 earthquake releases roughly a million times more energy than an Mw 4 earthquake, keeping in mind this is an approximate scaling and depends on rupture details.

Liquefaction occurs when saturated, loose sediments are jolted by shaking, causing the grains to rearrange and the pore spaces to change. Water between the grains resists compression, so excess pore water pressure builds up. This pressure lowers the effective stress that holds the grains together, causing the soil to behave more like a liquid and lose shear strength. As a result, the surface sediments settle and can collapse or subside, producing ground surface subsidence and sometimes lateral spreading. Other options describe processes that don’t involve this rise in pore water pressure in saturated sediments, so they don’t explain liquefaction-driven collapse.

A phase change is about rearranging the internal arrangement of atoms in a mineral without changing its chemical composition. When temperature or pressure shifts, a mineral can transform into a different mineral that has the same formula but a different crystal structure—that’s polymorphism. For example, calcite and aragonite are both CaCO3, but their atoms are arranged differently. The same idea applies to other polymorphs like quartz in its different high- and low-temperature forms. Metamorphism is the broader process that can drive mineral changes, but it isn’t defined by keeping the same composition with a new structure. Recrystallization mainly changes grain size or the form of the same mineral, and neocrystallization introduces minerals with new chemicals. So this scenario fits a phase change.

Bedding is the layered arrangement formed by successive episodes of sediment deposition in sedimentary rocks. In a simple rock sketch with three labels arranged left to right, the central annotation is typically taken to mark this main stratification because bedding represents the fundamental, continuous planar feature that runs through the rock mass and shows the overall layering pattern. Other terms point to different structural or metamorphic features: an axial plane relates to a fold’s symmetry and would be associated with folding geometry rather than the main layering; cleavage planes reflect metamorphic fabric from mineral alignment, not the original sedimentary layering; a contact marks the boundary between different rock types, which is a discrete feature rather than the pervasive layering. Thus, the middle annotation corresponds to bedding.