Intensity Lab
MMI Scale › Level I
I

Not Felt

Not felt shaking · None damage potential

PGA
< 0.05 %g
PGV
< 0.1 cm/s
I II III IV V VI VII VIII IX X

Not felt except by a very few under especially favorable conditions.

Effects

People & Response

  • Not generally felt by people
  • Detected only by sensitive instruments
  • Birds and animals may become uneasy

Objects & Furnishings

  • Trees and structures may sway very slowly
  • Doors may swing very slowly

Structures & Environment

  • No damage to structures
  • No perceptible ground motion
Typical PGA (ShakeMap) < 0.05 %g
Typical PGV (ShakeMap) < 0.1 cm/s
PGA/PGV ranges are approximate; values overlap between adjacent levels. See Instrumental Intensity for details.

Video Example

MMI I shaking example video thumbnail
Watch on YouTube ↗
Weak II →

Descriptions are verbatim from the USGS MMI Scale, based on Wood & Neumann (1931) and Richter (1958). Source: USGS Modified Mercalli Intensity Scale .

Instrumental intensity values and PGA/PGV ranges from USGS ShakeMap V4 Technical Documentation (Worden et al.). Intensity Lab reports MMI derived via the Worden et al. (2012) GMICE, interpolated from USGS ShakeMap. PGA/PGV ranges are approximate; actual values overlap between adjacent levels.