Read seismic-wave diagrams in ManYue: distinguish propagation from particle motion

P and S are not two earthquake danger ratings. Read original medium diagrams and a simplified arrival card in ManYue, checking particle motion, transmission medium and same-path speed assumptions separately. All numbers are paper assumptions, not live warnings or real source estimates. The app supports viewing and return, while the reader reasons from sources without automatic seismogram analysis.

Name medium diagrams and recorded traces separately

Draw A as solid-medium points with rightward propagation and left-right oscillation arrows. B propagates rightward with up-down oscillation. C is a separate schematic amplitude-versus-time record with assumed arrivals, not instrument data. Record file, location and arrow legend. Spatial diagrams and time traces are not interchangeable. Establish whether a drawing describes particle motion or a recorded signal before naming P or S; a rising curve alone does not mean transverse particle motion.

Identify parallel compression in P motion

A has particle motion parallel to propagation, illustrating P compression and dilation. Trace the disturbance while one point oscillates locally rather than travels from source to station. P motion can propagate in solids and fluids, but its speed varies with medium and is not a global constant. Exaggerated dot spacing illustrates compression, not literal giant fractures in rock. Retain the schematic exaggeration when explaining the diagram.

Identify perpendicular shear without changing propagation

B’s up-down particle motion is perpendicular to rightward propagation, illustrating S shear rather than upward travel of the whole wave. S waves propagate in solids, while fluids do not support this shear mode; do not draw a direct S path through the liquid outer core. Interface conversion and surface waves are outside this simplified body-wave exercise, not nonexistent because omitted. Both P and S can occur in solids; solids are not exclusively S and liquids exclusively P.

Compare arrival under one ideal path

Assume one station at a common straight path distance of one hundred twenty kilometres in uniform solid, with P speed six and S speed four kilometres per second. Distance over speed gives twenty and thirty seconds, a ten-second difference. Preserve all assumptions with the numbers. Layering, curved paths and varying speeds make real Earth more complex; an actual ten-second gap does not directly prove a source one hundred twenty kilometres away. Different paths also defeat a simple speed-only comparison of complex arrivals.

Separate time origin and arrival gap

With origin at the source event, mark twenty and thirty seconds. With origin at P arrival, mark zero and ten; the gap remains ten. State the origin rather than assume recording begins at source onset. Magnitude, intensity and arrival time are distinct quantities: thirty seconds is not magnitude thirty, and a plotted peak alone does not establish building damage. This exercise verifies model timing without invented instrument thresholds, noise or filtering data.

Mark inapplicable quantities for a liquid

For D change the segment to uniform liquid but do not carry solid speeds over automatically. P requires a new liquid-speed assumption; direct S propagation of this kind is inapplicable, not zero seconds, a measured infinity or proof of no earthquake. Missing S data can have other real-world causes involving paths, noise or instruments and require expert evidence. Separate inapplicable model quantities from quantities unknown because parameters are missing.

Check waveform and hazard-label confusion

A vertically varying C trace does not itself identify S: its vertical axis is not particle position. Earlier P arrival does not establish a hazard ranking. Reversed twenty/thirty-second results call for checking speed denominators and units. Follow sourced medium labels rather than call the entire mantle liquid. Share original diagrams and assumptions without issuing real warnings or evacuation advice from them. Unclear legends remain unresolved instead of turning this simplification into a complete Earth propagation model.

Reopen and deliver conditional results

Reopen and verify motion arrows, solid/liquid conditions and C’s time origin, then recalculate twenty seconds, thirty seconds and the ten-second gap. Explain particle motion versus propagation, medium restrictions and path/speed dependence. Retain parameters and inapplicable fields, not merely “P fast, S slow”. Reassess path or medium changes instead of reusing values after a bookmark return. Completion is diagram and example verification, not real earthquake analysis, device-sensor testing or hazard assessment.

Related guides and sources

Read strata in ManYue: separate deposition order from cross-cutting events; Read coordinate paths in ManYue: distinguish displacement from total distance.

Checked on November 14, 2026: Apple public information lists ManYue 2.0.5, requiring iOS / iPadOS 15.0 or later. See the official App Store for published capabilities; verify specific controls in the installed version.

Method reference: British Geological Survey: seismic-wave types and media. Samples, passages and controls are original exercises. Sources establish definitions and checking methods rather than new automatic analysis in the app. Manual records may be kept externally, and unknown fields should remain explicit. This article does not claim step-by-step testing on a physical device, private server or every output environment.