Forecast Published March 31 ——
April 20 Sanriku M7.7 Matches
2011 Great East Japan Earthquake Pattern
Our pre-published “April Danger Calendar” designated April 20–21 as AA Maximum Danger with QUAKE tag.
The earthquake struck on schedule. WHGR analysis reveals an exact numerical match with the 2011 foreshock sequence — and the depth data suggests the deepest lock has not yet released.
On March 31, 2026, White & Green published an “April Danger Calendar” based on the proprietary WHGR analysis engine (TigerProtocol). The calendar stated:
April 18–20: A+ Danger Level · WHGR −250
→ “Post-AA week. Watch for QUAKE, market, and geopolitical volatility.”
April 21: AA Maximum Danger · WHGR −325 · I-Cycle Active
→ “Second peak. Escalation confirmation expected.”
On April 20, an M7.7 struck off Sanriku. The Japan Meteorological Agency issued a post-earthquake alert for potential follow-on mega-quakes. This prediction is a timestamped, publicly verifiable record.
Sanriku Offshore M7.7 (Revised) ／ Seismic Intensity 5+ ／ Tsunami Warning
At 16:53 JST on April 20, 2026, an M7.7 earthquake struck off Sanriku (approx. 100km east of Miyako). Seismic intensity of 5+ was recorded in Aomori Prefecture. Tsunami warnings were issued for Hokkaido, Aomori, and Iwate. Depth: approximately 10km.
“Hokkaido / Sanriku Coast Post-Earthquake Alert” Issued
The JMA has officially issued a post-earthquake alert, stating that “the probability of an M8+ mega-earthquake is elevated above normal.” Residents across 182 municipalities in 7 prefectures from Hokkaido to Chiba are advised to “maintain special preparedness for one week” — a period that corresponds exactly to the high-WHGR window (April 21–27).
Prediction Calendar vs. Actual Events
| Date | Forecast Level | WHGR | Tags | Actual Result |
|---|---|---|---|---|
| Apr 18 (Sat) | A+ Danger | −250 | QUAKE MARKET | Nagano M5.0→5.1, Intensity 5+HIT |
| Apr 19 (Sun) | A+ Danger | −250 | QUAKE MARKET | Nagano swarm continuesHIT |
| Apr 20 (Mon) | A+ Danger | −250 | QUAKE MARKET | Sanriku M7.7, Tsunami WarningHIT |
| Apr 21 (Tue) | AA Maximum | −325 | QUAKE WAR OIL | I-Cycle Active ← Watch closely |
| Apr 22 (Wed) | A+ | −205 | Afterwave | — |
| Apr 23 (Thu) | A+ | −230 | Afterwave | — |
Exact Match with 2011 Great East Japan Earthquake Pattern
Cross-referencing today’s seismic sequence with the sexagenary cycle (六十干支) and WHGR values from 2011 reveals a striking numerical coincidence.
| Event | Date | Magnitude | Depth | Stem-Branch | P-WHGR | W-WHGR |
|---|---|---|---|---|---|---|
| 2011 Foreshock ① | Mar 9 | M7.3 | 8km | 癸卯 Gui-Mao | +108 | −54 |
| 2011 Foreshock ②FORE | Mar 10 | M6.8 | 9km | 甲辰 Jia-Chen | +162 | 0 |
| GREAT EAST JAPANMAIN | Mar 11 | M9.0 | 24km | 乙巳 Yi-Si | +216 | +54 |
| Nagano M5.0 | Apr 18 | M5.0 | 10km | 壬寅 Ren-Yin | +54 | −108 |
| TODAY’S QUAKE | Apr 20 | M7.7 | 10km | 甲辰 Jia-Chen | +162 | 0 |
| TOMORROWALERT | Apr 21 | — | — | 乙巳 Yi-Si | +216 | +54 |
| Apr 22PEAK | Apr 22 | — | — | 丙午 Bing-Wu | +270 | +108 |
April 20, 2026 (Jia-Chen) shares the exact same stem-branch and WHGR values as March 10, 2011 (Jia-Chen) — the second foreshock of the Great East Japan Earthquake. Note that the March 10 event was initially classified as an “aftershock” of March 9; it was only retroactively identified as Foreshock ② after the M9.0 struck the following day. The same uncertainty applies to today.
April 21 (Yi-Si) carries the same stem-branch and WHGR values as March 11, 2011 — the day of the M9.0 main shock.
The Depth Argument: The Deep Lock Has Not Yet Released
Depth Comparison — 2011 Foreshock Sequence vs. 2026
The 2011 foreshocks (8–9km) were shallow crustal events. The main shock (M9.0) penetrated to 24km — reaching the plate boundary interface and triggering catastrophic rupture. Today’s M7.7 at 10km depth mirrors the 2011 foreshock profile. The deep interplate lock may not yet have released.
“Shallow” does not mean “safe.” In the 2011 sequence, shallowness characterized the foreshock phase. The deepening to 24km was the catastrophic transition.
Also noteworthy: the 2011 Aizu swarm occurred after the March 11 main shock (induced seismicity). In contrast, the 2026 Nagano swarm preceded the Sanriku event — the sequence is reversed. The inland faults appear to have moved first this time.
Critical Time Windows: April 21–22
In 2011, foreshocks occurred immediately after “Bing-× hour” (P-WHGR peak at +270) transitions into “Ding-× hour” (sharp drop to −216). The same pattern appears on April 21–22.
🔴 Maximum Alert Time Bands
| Date/Hour (JST) | Hour Stem-Branch | Hour P-WHGR | Total | Note |
|---|---|---|---|---|
| Apr 21 00:00 | 丙子 Bing-Zi | +270 | +378 | Peak — same structure as 2011/3/11 00:00 |
| Apr 21 20:00 | 丙戌 Bing-Xu | +270 | +378 | Peak |
| Apr 21 22:00 | 丁亥 Ding-Hai | −216 | −54 | Sharp drop — pre-shock pattern |
| Apr 22 16:00 | 丙申 Bing-Shen | +270 | +378 | Double peak (day value also +270) |
| Apr 22 18:00 | 丁酉 Ding-You | −216 | −54 | Sharp drop ← closest match to 2011 pattern |
Weekly WHGR Overview: April 20–27
| Date | Day | Stem-Branch | P-WHGR | W-WHGR | Total | Alert |
|---|---|---|---|---|---|---|
| Apr 20 | Mon | 甲辰 Jia-Chen | +162 | 0 | +162 | M7.7 struck today ◀ |
| Apr 21 | Tue | 乙巳 Yi-Si | +216 | +54 | +270 | 🟠 High Alert / JMA warning period |
| Apr 22 | Wed | 丙午 Bing-Wu | +270 | +108 | +378 | 🔴 Maximum Alert (P-WHGR peak) |
| Apr 23 | Thu | 丁未 Ding-Wei | −216 | +162 | −54 | 🟡 Caution |
| Apr 24 | Fri | 戊申 Wu-Shen | −162 | +216 | +54 | — |
| Apr 25 | Sat | 己酉 Ji-You | −108 | +270 | +162 | 🟡 W-WHGR peak |
| Apr 26 | Sun | 庚戌 Geng-Xu | −54 | −216 | −270 | — |
| Apr 27 | Mon | 辛亥 Xin-Hai | 0 | −162 | −162 | — |
Context: The 270-Year Civilization Cycle
White & Green’s 270-Year Civilization Cycle Theory, based on Lomb-Scargle spectral analysis of Japan’s earthquake catalog (M6+, N>1,400 events), identifies three trigger waves: 4.61, 3.53, and 1.95 years — each within 1% of 270 ÷ integer. The three-wave convergence window falls at 2027.4–2028.6 and 2034–2038. The latter represents the window for a civilization-altering mega-quake.
April 2026 falls outside these windows. Our assessment: potential for M8 or repeated M7-class events, but not a civilization-scale rupture.
Paper D: “Lattice Extension of the 270-Year Cycle and Seismic Periodicity” · DOI: 10.5281/zenodo.19302054
Paper E: “Hegemonic Transition Cycles and Seismic Convergence” · DOI: 10.5281/zenodo.19302143