This map, created by Alexander Keith Johnston, appears inside the book The Physical Atlas of Natural Phenomena, published in 1856 by William Blackwood and Sons.

The world map, which occupies the upper part, focuses on the distribution of active and inactive volcanoes around the world, with the information available in the mid-19th century. In addition, coloured lines represent areas affected by major earthquakes or earthquake sequences.

Below are detailed maps of areas with high volcanic or seismic activity: Iceland, Santorini (Greece), New Zealand, Hawaii, Canary Islands, Greek Islands, Italy and Sicily, Central America and Southeast Asia.

Johnston's map is strongly influenced by the theories of Alexander von Humboldt, who laid the foundations of geophysics and seismology in the first half of the 19th century. It is also striking how this descriptive map already showed clearly along certain lines that, a century later, would prove to be boundaries of tectonic plates.

Sources

• Volcanic action.