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      • ShakeMaps & Intensity

      GlobalQuake Zoomed-in ShakeMap

      GlobalQuake provides real-time ShakeMaps — colored hexagonal overlays on the globe that show estimated shaking intensity in the area affected by an earthquake. These maps help you quickly understand which regions are experiencing shaking and how strong it is.

      How ShakeMaps Work

      ShakeMaps use a hexagonal grid system to divide the Earth's surface into hexagonal cells. Each cell is colored based on the estimated shaking intensity at that location.

      The grid resolution adapts automatically based on earthquake magnitude:

      MagnitudeResolutionCell Size
      ≤ 4.96Smallest
      < 6.45Small
      < 8.54Medium
      ≥ 8.53Largest

      Larger earthquakes use coarser grids to cover their wider impact area, while smaller earthquakes use finer grids for precision.

      Ocean cells are filtered out, so you only see shaking estimates over land. Each hexagon is rendered as a semi-transparent overlay on the 3D globe, and hovering over a hex displays the intensity level name.

      Modified Mercalli Intensity (MMI) Scale

      The default intensity scale used by GlobalQuake is the Modified Mercalli Intensity (MMI) scale. It measures the perceived effects of shaking at a given location.

      LevelColorDescription
      I■ GrayNot felt
      II■ Light purpleBarely felt
      III■ BlueFelt by many
      IV■ Light blueFelt by all
      V■ Bright greenStrong shaking
      VI■ YellowStrong shaking
      VII■ Orange-yellowVery strong
      VIII■ OrangeSevere
      IX■ RedViolent
      X■ Dark redExtreme
      XI■ Very dark redExtreme
      XII■ Near-black redCatastrophic

      Shindo Scale

      GlobalQuake also supports the Shindo (震度) scale, commonly used in Japan. Shindo measures the intensity of shaking at a specific location rather than the earthquake's overall magnitude.

      LevelColorName
      1■ Teal-gray1
      2■ Blue2
      3■ Green3
      4■ Gold4
      5-■ Orange5弱 (5-lower)
      5+■ Deep orange5強 (5-upper)
      6-■ Red6弱 (6-lower)
      6+■ Dark red6強 (6-upper)
      7■ Purple7

      City Intensities

      For each earthquake, GlobalQuake displays a list of up to 14 cities on the right side of the screen showing estimated intensity. The list includes:

      • Top 9 cities ranked by peak ground acceleration (PGA)
      • Top 5 additional cities ranked by felt population (people who may have felt the shaking)

      Each entry shows the city name and its intensity level (e.g., "Tokyo: 5+").

      Below the city list, two population estimates are displayed:

      • Possibly felt by: Number of people who may have felt the shaking
      • Possibly heavily felt by: Number of people who may have experienced strong to severe shaking

      Configuring Intensity Display

      You can customize how ShakeMaps and intensity data appear in the settings:

      SettingDescription
      Display ShakeMapsToggle the hexagonal grid overlay on or off
      Display City IntensitiesToggle the city intensity list on or off
      Intensity Scale IndexChoose between MMI (0) and Shindo (1)
      Shakemap Quality OffsetAdjust grid resolution from -4 (coarser) to +4 (finer)
      Display Home LocationShow a marker at your home location on the globe

      The Shakemap Quality Offset lets you fine-tune the resolution beyond the default magnitude-based scaling. Lower values produce larger hexagons for faster rendering, while higher values show more detail.