About QuakeSimulator

QuakeSimulator answers a question no other public tool answers: "If a magnitude X earthquake hit HERE, what would happen near me?"

The disclaimer that holds it all together

This is not precision engineering — go to the government sites for that. This is one engineer with a milk crate and some duct tape that happens to be manufactured by a Crazy Uncle from Iowa Industries (Dubuque) and distributed by Steve Erkal's Building Supply. It's Memphis-approved — that's what's holding all this together. Real numbers? FEMA Hazus, USGS ShakeMap. Not us.

What's new in v0.4.7

• 🔬 Zoom-aware Level-of-Detail — what you see changes as you zoom in or out. Macro view shows bridges + top critical infrastructure; zoom in for hospitals and schools; zoom in further for commercial/industrial; zoom to building grade for residential. The little badge bottom-right tells you what grade you're on.
• 🤫 Quiet Mode — click the grade badge to toggle. In quiet mode residential stays hidden until you zoom in to building grade. Default mode shows residential only inside your current viewport (it follows your eye, never crowds the macro view).
• 🌐 NSI Cloudflare Worker — USACE NSI lacks CORS headers and ships 166 MB payloads for Memphis-class counties. A tiny proxy worker handles the CORS + filters server-side so the panel actually loads in a browser.
• 🏥 Critical infra across ALL rings, not just outer — the previous build saturated its FEMA query on urban clusters and starved the inner rings. v0.4.6 added a separate inner-ring query + dedupe, so hospitals and schools render at every ring depth.
• 🌉 Collapsible top-tier bridges + clickable list — the Interstate/Freeway list is now collapsible, and any bridge name in the right panel pings its marker on the map.
• 🛡 Graceful degradation — when a federal API rate-limits or a worker times out, the panel says why in plain language and points at what still works. No more cryptic JS errors in the UI.

From v0.4 (the NSI lift)

• 🏗 NSI integration — USACE's National Structures Inventory replaced FEMA USA Structures for the inner ring. Brought year built, building type (wood/masonry/steel/concrete), 2 AM and 2 PM population, and structure dollar value per building.
• 🌉 NBI Bridges — toggle in the layer controls. FHWA National Bridge Inventory across the affected area. Bridges color-coded by functional class — interstates first, then arterials, then collectors. Click any marker for year built, ADT, scour-critical status.
• Population by time of day — "Inside MMI VII zone: 6,400 people at 2 AM, 14,200 at 2 PM" — the PAGER-style fidelity NSI makes possible.

From v0.3.1

• 📜 Historical context panel — top 10 historical earthquakes within 250 mi from USGS's catalog (since 1900)
• Dynamic inner ring — strongest existing MMI ring gets per-building rendering at any magnitude
• Critical infrastructure across the full felt area — hospitals/schools/government/assembly across MMI III

Earlier

• v0.3 — FEMA USA Structures integration, three-tier render strategy, exposure caveat
• v0.2 — search bar, satellite toggle, ~16 quake research labs, historical analog detector
• v0.1 — base scenario builder, USGS live feed, MMI rings

Data sources

USGS earthquake feeds + FDSN catalog · OpenStreetMap Nominatim (geocoding) · Esri World Imagery (satellite) · USGS National Seismic Hazard Model 2023 (faults) · USACE National Structures Inventory (NSI) · FHWA National Bridge Inventory (NBI) · FEMA / Oak Ridge National Laboratory USA Structures (county counts) · FCC Block API (lat/lon → FIPS reverse geocoding).

Built by

SnapBasin LLC — civic-tech engineering tools company. Sister tools: SnapBasin · Watershed Pulse · Space Pulse · Quantum Pulse.

Educational use only. Not for emergency planning, structural engineering, or insurance underwriting. Not affiliated with USGS, USACE, FEMA, FHWA, or any government agency. No tracking.

How the math works

QuakeSimulator predicts ground shaking intensity using a Ground Motion Prediction Equation (GMPE) — the same kind of equation USGS and FEMA use professionally, simplified for citizen-facing use.

The equation (simplified)

log₁₀(PGA) ≈ -2.0 + 0.5·M − 1.5·log₁₀(R + 10) − 0.0018·R

Where M is magnitude, R is distance to epicenter (km), PGA is Peak Ground Acceleration (g). Coefficients informed by real events: Tohoku 2011 (M9.1), Loma Prieta 1989 (M6.9), Northridge 1994 (M6.7). The final −0.0018·R term is anelastic attenuation — seismic energy is absorbed as it travels, so shaking fades faster at long range and large quakes don’t read as “felt everywhere.”

From PGA to "how it feels"

PGA → Modified Mercalli Intensity (MMI) via USGS Wald 1999 conversion:

• III — felt indoors, hanging objects swing
• IV — windows rattle, dishes shake
• V — felt by all, small objects fall
• VI — strong shaking, plaster cracks
• VII — very strong, weak buildings damaged
• VIII — severe, ordinary buildings damaged
• IX — violent, well-built buildings damaged
• X+ — extreme, most masonry destroyed

Building exposure (FEMA USA Structures)

Within each shaking ring we query FEMA's USA Structures dataset — every building footprint >450 sq ft, with occupancy class. Three tiers:

• Strongest ring — every building rendered as dot, colored by occupancy class. Capped at 1,000 features (FEMA service limit). At M4-5 this is the MMI IV ring; at M7+ this is the MMI VII ring.
• Critical infrastructure (full felt area) — hospitals, schools, government, assembly across the entire MMI III ring with distinct icons.
• Outer ring (MMI III) — total building count via returnCountOnly, no dot rendering.

Historical context (USGS FDSN)

For any epicenter we query USGS's FDSN catalog — every recorded earthquake worldwide. We pull the top 10 by magnitude within 400 km (~250 mi) of the chosen epicenter, since 1900. This isn't to discourage simulation — it's to show you what's actually shaken this region before.

What we're NOT modeling

Local soil amplification (Vs30 site class), liquefaction, surface rupture, tsunami generation, building-specific structural response, fires, landslides, year-built or seismic-class of any individual building. USA Structures gives us footprints — not the construction details that would let us predict damage. What you see is exposure: which buildings sit where the shaking is. For professional analysis: FEMA Hazus or USGS ShakeMap.