A band of unusually hard rock, formed from magma about 15 million years ago, near the epicenter of the 2024 Noto Peninsula earthquake likely worsened the disaster as internal faults collapsed following the initial tremor, Japanese researchers have said in a newly published paper.
The findings help explain why a series of small earthquakes, known as a swarm, over a period of about three years in northeastern Noto suddenly culminated in the magnitude 7.6 Noto Peninsula quake on Jan. 1, 2024, which registered shindo 7, the highest level on Japan’s seismic intensity scale.
The paper, written by Tohoku University researchers and published Wednesday in scientific journal Science Advances, states that the huge body of hard rock — referred to by the team as “ancient magma” — sits under the ground just west of the epicenter, roughly 5 to 15 kilometers deep and about 10 to 15 km wide.
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