Where does “関東地震” come from?

関東地震 (Japanese) comes from Japanese 地震, from Japanese 地, from Middle Chinese 地.

関東地震 (Japanese): A megathrust earthquake occurring at Sagami Trough off the coast of Kantō Region in Japan once in a few centuries, especially that occurred on September 1, 1923

Definitions

A megathrust earthquake occurring at Sagami Trough off the coast of Kantō Region in Japan once in a few centuries, especially that occurred on September 1, 1923

Ancestry of “関東地震”, step by step

関東地震 traces back through two separate lines of ancestry.

via Japanese 地震

Step	Language	Word	Meaning
1	Japanese	地震	an earthquake
2	Japanese	地	earth, dirt; fabric, cloth; territory
3	Middle Chinese	地	—

via Japanese 関東

Step	Language	Word	Meaning
1	Japanese	関東	the shogunate
2	Japanese	箱根の関	tollgate of {{w\|Mount Hakone}}

Every word from Middle Chinese 地 →Every word from Japanese 地 →Every word from Japanese 地震 →