Methodology

Data Collection

EarthquakePeek compiles earthquake data from authoritative sources:

• USGS Earthquake Hazards Program — Primary source for earthquake event data including magnitude, location, depth, felt reports, and PAGER alert levels. Data accessed via the USGS Earthquake Catalog API.
• USGS National Seismic Hazard Maps — Used for state-level risk assessments and seismic zone identification.
• Published Geological Research — Peer-reviewed studies on fault characterization, seismic history, and risk modeling.
• State Geological Surveys — State-specific seismic data and hazard assessments.

Risk Scoring Methodology

State earthquake risk scores (1-10) are calculated using a weighted combination of:

• Historical seismicity (40%) — Frequency and magnitude of past earthquakes within and near the state.
• Fault proximity (25%) — Proximity to known active fault systems and their maximum credible earthquake potential.
• USGS hazard probability (20%) — USGS probabilistic seismic hazard assessment values.
• Population exposure (15%) — Percentage of state population in areas with significant seismic hazard.

Earthquake Selection

Our database includes 470 earthquakes selected for their significance based on magnitude (generally M4.5+), felt impact, tsunami potential, and damage reports. This represents a curated subset of the millions of earthquakes recorded by the USGS, focused on events most relevant to public safety and awareness.

Seismic Zone Classification

Seismic zones are classified by type (transform, subduction, intraplate, etc.) and risk level based on their historical activity, maximum credible earthquake potential, and proximity to populated areas. Zone boundaries follow geological consensus from published fault maps.

Updates

We review and update our database regularly to incorporate new significant earthquakes, revised magnitude estimates, and updated risk research. Historical data is periodically reconciled with USGS catalog revisions.

Limitations

Our data represents a snapshot of earthquake activity and risk assessment. Earthquake science is continually evolving, and risk estimates may change as new research is published. Our state-level risk scores are generalizations — actual risk varies significantly at the local level based on soil conditions, building stock, and proximity to specific fault segments.