Your phone already contains the same basic type of sensor a seismometer uses — an accelerometer, which measures acceleration along three axes. That's genuinely interesting, and it's the reason apps like MyShake (a real crowdsourced earthquake-detection project) can use ordinary phones as a distributed sensor network. But there's a big gap between "has an accelerometer" and "is a seismometer."
What a real seismometer does differently
Professional seismometers are:
- Isolated from everyday vibration (mounted on bedrock or deeply anchored, away from footsteps, traffic, wind).
- Extremely sensitive — designed to detect ground motion measured in micrometres.
- Calibrated against known reference standards, so their output means something in absolute physical units.
A phone sitting on a table, by contrast, picks up every vibration nearby — footsteps, a door closing, a truck outside, the table itself — with no isolation and no calibration. It's a general-purpose motion sensor, not a scientific instrument.
What a phone's accelerometer is good for
Despite that, it's a genuinely useful rough tool for:
- Comparing vibration — is this washing machine vibrating more than that one? Is this floor shakier than that one?
- Noticing something changed — a machine that used to run smoothly and now shakes noticeably.
- Curiosity and demonstrations — seeing just how sensitive the sensor in your pocket actually is.
Separating "shake" from "tilt"
A raw accelerometer reading always includes gravity — tilt the phone and the reading changes even with zero actual vibration. A useful vibration meter needs to separate the slow-changing "which way is down" signal from the fast-changing "something is shaking" signal — typically done with a high-pass filter that tracks a slow-moving baseline and reports only the deviation from it.
Try it — with the right expectations
The free Vibration Meter does exactly this filtering and shows a live g-force reading with a simple Still/Slight/Moderate/Strong scale. It's built for practical, everyday vibration checks — not for detecting or reporting real earthquakes, which needs certified equipment and official monitoring networks.