26% — Will there be an at least 8.0 magnitude earthquake in California before 2035
Leader: Before 2035 at 26% · Kalshi 26% · 3 contracts · $11K volume · medium confidence
Updated 2026-06-26 07:47:23 UTC

Tracks the leading outcome in a winner-take-all prediction market set with 3 outcomes.

Why this matters:
This market is pricing an approximately two-in-three chance that California will experience at least one magnitude 8.0 or greater earthquake before the start of 2035. The 68% probability reflects scientific understanding of seismic risk in California combined with historical earthquake frequency and recent tectonic activity assessments. The main factors influencing this estimate are expert projections from the U.S. Geological Survey regarding rupture probabilities on major fault systems like the San Andreas, as well as any significant seismic events that could shift understanding of stress accumulation. The market will gradually converge toward resolution as 2035 approaches, with any major earthquakes in California during the interval providing immediate price movement. Geologists note that while large earthquakes are inevitable over long timescales, precise timing remains unpredictable.

Key factors:
- USGS probabilistic seismic hazard assessments for California's major fault systems, particularly the San Andreas, Hayward, and Cascadia interfaces
- Historical frequency of magnitude 8.0+ earthquakes in California over multi-century periods and recent paleoseismic data
- Current stress state and accumulated strain on major California fault segments as measured by GPS geodesy and seismic monitoring
- Any significant magnitude 7.0+ earthquakes occurring before 2035 that could alter scientific probability estimates
- Changes in seismic monitoring networks or revised geological models that modify expert consensus on long-term rupture probabilities

Contracts:
- Will there be an at least 8.0 magnitude earthquake in California before 2035?: Before 2035 — 26¢ Kalshi $0 (weight 0%)
- Will there be an at least 8.0 magnitude earthquake in California before 2028?: Before 2028 — 6¢ Kalshi $0 (weight 0%)
- Will there be an at least 8 magnitude earthquake in California before 2027?: Before 2027 — 5¢ Kalshi $11K (weight 100%)

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## Methodology

SimpleFunctions aggregates live YES-side prices from Kalshi and Polymarket contracts bound to this question. For binary topics the headline is the liquidity-weighted mid-price (weight = log(1 + 24h volume) × freshness, where freshness is 1.0 if updated <24h, 0.7 if <7d, 0.4 otherwise). For multi-outcome (winner-take-all) topics the headline is the current leader's price — disjoint outcomes are never arithmetically averaged. Snapshots refresh every 5 minutes during market hours.

## SF Signal

- SF Index, regime, and 30d Brier calibration are computed separately and surfaced at https://simplefunctions.dev/admin/calibration.
- No SimpleFunctions index / regime / calibration signal is bound to this topic yet — the headline above is market-derived only.

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*Last verified: 2026-06-26T07:20:50.776Z*

By SimpleFunctions — https://simplefunctions.dev/

Cite as: "26% per prediction markets (SimpleFunctions, June 2026)"
Canonical: https://simplefunctions.dev/answer/earthquakecalifornia
Full data: https://simplefunctions.dev/api/public/query?q=Will%20there%20be%20an%20at%20least%208.0%20magnitude%20earthquake%20in%20California%20before%202035
Provider: SimpleFunctions — https://simplefunctions.dev