When the ground moves, stories surface—about how faults fail, why small quakes ripple across provinces, and how a few seconds of warning can change outcomes. We sit down with seismologist Marika from Earthquakes Canada to translate seismic science into everyday clarity and practical steps that keep people safer.

We start with the core mechanics: stress, friction, and sudden slip along faults that launch P and S waves through the crust. Marika breaks down why the old, cold, and uniform rocks of eastern Canada carry shaking so efficiently, making a magnitude 3.7 detectable from Kingston to London. She separates magnitude from intensity—one energy, many experiences—and explains why modern hazard work uses moment magnitude instead of the original, region‑specific Richter scale. Expect a clear take on logarithmic scaling, those pesky decimals, and what really dictates the shaking you feel at home.

From Cascadia’s subduction zone to frostquakes that pop on winter nights, we map natural and human‑influenced sources of shaking, including how fluid injection can induce small events by changing pore pressure on faults. Marika gives a rare look inside a seismologist’s day: monitoring nationwide stations, locating events by P and S arrivals, filtering “noise” from trains and mines, and feeding data into Canada’s seismic hazard maps. Those maps shape the National Building Code so bridges, hospitals, and homes match regional risk, whether you live in BC or along the Ottawa–Montreal corridor.

We also cover Canada’s Earthquake Early Warning system—how dense sensors catch the first P wave and push alerts before damaging S waves arrive, buying tens of seconds for trains to brake and people to drop, cover, and hold on. Want to help? Submit a “Did You Feel It?” report after you notice shaking; thousands of citizen reports sharpen intensity maps and improve future planning. If you learned something new, share this conversation with a friend, subscribe for more under‑the‑canopy science, and leave a review to help others find the show.