Strong earthquake hits northern Japan, tsunami warning issued
Tsunami size, models, and risk
- Early links from tsunami agencies and USGS suggested up to ~1 m waves; later JMA maps showed observed waves around 0.7 m.
- Some posters argue 1 m is still dangerous, stressing debris, sewage, chemicals, and retreating flows.
- Others compare 1–2 m tsunamis with typical storm or hurricane waves, noting tsunami waves carry more energy because the entire water column moves.
- There’s criticism of Japan’s Meteorological Agency tsunami-height estimates: one commenter claims the model “defaults” to ~3 m and erodes trust by over-warning; others push back that estimates and measurements are different things.
How the quake felt and local impact
- People in northern Japan (Misawa, Rokkasho, Sapporo, Niseko) describe very strong but largely non-destructive shaking: items off shelves, sloshing fish tanks, some lobby evacuations, but little structural damage reported by individuals.
- One local notes it was the strongest recorded in that region, yet their house suffered only minor interior disruption; later confirms the tsunami warning was lifted with no major damage.
- Tokyo residents report clear, sustained shaking. Depth is discussed: a relatively deep hypocenter is seen by some as reducing destructive potential, though aftershocks include shallower events.
Psychology, safety, and preparedness
- Reactions to earthquakes range from excitement (trust in Japanese/Californian building codes) to intense panic, especially for those unused to ground motion.
- Balance-heavy sports (skating, skiing) are suggested as making people more comfortable with instability.
- Practical advice: stay inside modern buildings rather than running out; avoid falling debris and glass; secure bedroom items; keep shoes, water, and an emergency kit ready.
- Some visitors consider leaving Hokkaido due to official advisories about elevated risk of a larger quake; others argue you can’t meaningfully “time” megaquakes.
Earthquake science, “small quakes,” and megathrust fears
- Commenters debate whether frequent smaller quakes reduce the chance of a “big one.”
- One side: earthquakes release stored stress, so many small events should help; they cite videos and some research on stress and fault strength.
- The other side: solid-earth seismology often calls “small quakes prevent big ones” a myth; small events don’t reliably predict or forestall major ruptures, and most energy is released in the largest quakes.
- Official estimates (e.g., ~5% chance of a larger quake within a week after a big one) are referenced, emphasizing high uncertainty in prediction.
- Casual claims that this is “buildup for a 9+ megathrust earthquake” are widely dismissed as unsupported speculation.
Alerts, information systems, and language trivia
- Japanese emergency phone alerts are reported to work for at least some foreign eSIM users.
- Tsunami.gov’s UI is criticized as confusing and uninformative.
- There’s some seismological terminology/etymology talk (epicenter vs. hypocenter, Greek roots) and comparisons to past events (2011 Tōhoku, Christchurch, liquefaction videos).