Kantō Plain

In general, the whole area is slightly bent and forming a basin centered in the Tone River and Tokyo Bay.

[2] The Kantō Plain witnessed its greatest devastation from an earthquake on 1 September 1923, with a death toll calculated of 142,807.

As a result, sediment from the surrounding mountains was deposited very thickly (the Tertiary layer reaches as high as 3,000 meters) and further uplifted to form many hills and plateaus.

Large tectonic lines such as the eastern margin of the Fossa Magna and the Median Tectonic Line are thought to exist in the central part of the plain, but this thick accumulation of soft sedimentary layers makes it difficult to find active faults that can cause earthquakes (faults exist in the base 3000m below the sedimentary layers).

Thunderclouds that form in the northern to western mountains areas before noon reach the plains in the early afternoon, often resulting in evening showers (thunderstorms).

Throughout the year, the entire Kanto Plain, especially the inland areas, are easily affected by radiative cooling due to clear skies and north winds, so the minimum temperature before sunrise can drop to about 5 degrees below zero in winter.

The lowest temperatures in central Tokyo are higher than those in surrounding areas due to the heat island effect.

Kumagaya tends to get hotter because of being inland, foehn phenomenon, which occurs when the wind in the sky above blows down after crossing the mountains on the north and west sides of the Kanto Plain, and the sea breeze that warms up while passing through central Tokyo.