「何かが地盤を持ち上げている…異変」1000年に一度の地震のはずが【石川・能登半島地震】

MRO北陸放送公式チャンネル

11 Jan 202408:04

Summary

TLDRThe video discusses a major 7.6 magnitude earthquake that struck the Noto peninsula area in Japan in March 2022. It provides analysis from researchers who had been studying increased seismic activity in the region in recent years. The earthquake occurred on an underwater fault line that spans about 150km, which helps explain the strength of the shaking. There is discussion of continued earthquake risk in the region going forward.

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Q & A

What was unusual about the ground deformation observed before the earthquake?
-The 7 cm of ground deformation was very unusual for a non-volcanic region like Noto Peninsula.
How did researchers confirm the presence of an electrically conductive region underground?
-By installing observation equipment from November 2021, they detected a red, electrically conductive region underground near where the earthquake swarm began.
What mechanism is hypothesized to have caused the Noto Peninsula earthquake?
-Researchers believe an underground fluid like water rose up, lifted the peninsula's ground, and flowed into an offshore fault, causing it to slip and trigger the strong shaking.
What was the worst-case scenario that had researchers concerned?
-That the fluid would reach and trigger the nearby underwater active fault, resulting in a magnitude 7 earthquake.
Why was the earthquake larger than expected?
-The 150 km long fault that moved was longer than expected. Noto Peninsula sits above the fault, so movement of the entire fault caused strong shaking over a wide area.
How much did parts of Wajima City uplift due to the tectonic deformation?
-Some areas uplifted by as much as 4 meters.
How has the tectonic deformation affected coastal areas?
-In some places the coast expanded by 200 meters. Fishing ports are unusable, causing issues for the recovery of the fishing industry.
What are the implications for future earthquakes in the region?
-The ends of the fault that did not slip this time have built up strain and are at higher risk. Magnitude 6+ quakes causing strong shaking are still possible.
When did a similar past earthquake happen in the region?
-In 1983, the Japan Sea Nihonkai Chubu earthquake caused devastating tsunami damage. A large aftershock then hit the northern end of the fault.
What scale of earthquakes are no longer as likely in the Noto region now?
-Magnitude 7 quakes are less likely now that strain has been released, but locally strong magnitude 6 shakes are still possible.

Outlines

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Mindmap

Keywords

💡地震

The main theme of the video is about the large earthquake that occurred in March 2022 off the coast of Fukushima prefecture in Japan. The term 地震 (earthquake) appears many times throughout the script when referring to this major seismic event as well as previous and potential future earthquakes in the region.

💡規模

A key aspect discussed is the large scale or 規模 (magnitude) of the March 2022 earthquake, which measured 7.4, exceeding what researchers had anticipated for that fault line. The magnitude relates to the amount of energy released and severity of shaking.

💡活断層

The earthquake is explained to have occurred due to slippage along a major fault line or 活断層 (active fault) running along the ocean floor off the coast of Fukushima. This was an unknown and unmapped fault line prior to the quake.

💡地殻変動

Researchers had detected signs of ground deformation or 地殻変動 (crustal movement) in the years leading up to the quake, indicating shifting underground and building strain along the fault line.

💡余震

The seismic activity is expected to continue with many aftershocks or 余震 (aftershocks) expected along the ends of the fault line in surrounding regions, including strong magnitude 6+ quakes.

💡歪

Areas at the ends of the activated fault line are said to have accumulated strain or 歪 (distortion) and so at high risk for further quakes as the distortion seeks relief.

💡断層のずれ

The actual mechanism for such a large quake is explained as due to fault slip or 断層のずれ (fault displacement) along a 150 km stretch of the underwater fault near Fukushima, essentially the entire fault giving way.

💡地震の揺れ

The displacement along the extensive fault line led to intense shaking or 地震の揺れ (earthquake shaking) over a wide area, as high as a 6+ on the seismic intensity scale.

💡津波

While shaking impacts were widespread, the quake also generated a major tsunami or 津波 (tsunami) in some coastal areas, damaging ports and fisheries infrastructure.

💡浅間山

There is also discussion about potential linkage between the quake and volcanic activity at nearby Mt. Asama, but this connection is still being investigated by researchers.

Highlights

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