Pocket Seismograph

Turn your phone into a pocket seismograph. Place it on any surface — see the live trace, capture peaks, save sessions, export clean CSV. Free forever.

Pocket Seismograph turns your phone into a real vibration measurement instrument. Place it on any surface, washing machine, HVAC unit, floor, dashboard, or building beam, and watch the live trace draw what is actually happening. Catch the peak. Read the intensity. Save the session. Export clean CSV.

No ads. No account. No cloud. Forever.

WHAT IT DOES

Live measurement

• Real-time accelerometer trace, smooth and readable
• Magnitude or full XYZ axis display
• NOW, MAX, AVG, RMS metrics, updated continuously
• Pinch to zoom, pan to inspect, freeze without stopping
• Auto-scale fallback so tiny vibrations are still visible

Felt intensity (Mercalli)

• Live estimate of Modified Mercalli Intensity (I to X+)
• Based on peak ground acceleration (Wald 1999, USGS standard)
• Clearly disclaimed as estimated felt intensity, not a certified seismic measurement
• Calculated only in gravity-removed mode for accuracy

Three processing modes

• Raw: every accelerometer sample untouched
• Stable: smoothed for clean readings
• Vibration: gravity removed, true motion only The current mode is always visible. Every export tags which mode produced the data.

Reliable CSV export

• System Save dialog with full user control over location
• Standard, Excel-friendly, or Auto profile (locale-aware delimiter and decimal)
• Magnitude-only or full XYZ + magnitude columns
• ISO timestamps + millisecond offsets
• File is opened and validated after writing, never empty, never silent failure

Sessions and history

• Start, pause, resume, save with name, note, tags
• Search and filter your archive
• Open any session for the full chart, peak marker, and exact metrics
• Re-export any session at any time

Calibration wizard

• Measure baseline noise on your specific device
• Get recommended sensitivity, fixed Y range, and threshold
• Reset anytime in Settings

BUILT FOR REAL LIFE

• Washing machine off-balance? See exactly how bad.
• HVAC humming louder than usual? Document for the repair tech.
• Construction next door? Log evidence with timestamps.
• Felt a tremor? Capture the next one.
• Car shaking at speed? Quantify before the mechanic.

PRIVACY YOU CAN VERIFY

• Zero network requests for any core feature
• No analytics SDK, no tracker, no advertising ID
• No account, no login, no email
• All data stays on your device until you choose to share it
• Open standards: ISO timestamps, plain-text CSV, no proprietary format

NOT FOR

Pocket Seismograph is a research-grade and educational tool. It is NOT a substitute for certified seismic instruments, structural engineering assessments, or legal evidence in compliance contexts. Phone accelerometers vary across devices; use the calibration wizard for best accuracy.

For earthquake early warnings, please use your country's official seismic alert system.

Built by an independent developer who refuses to put ads or paywalls on a measurement instrument. If Pocket Seismograph helps you, the best thanks is a review.