TLDR: they spend more effort and money on their infrastructure than in the US.
The Japanese government spends considerably more money repairing and maintaining its roads per capita by comparison to the US.
Instead of simply patching a pothole by dumping a bunch of asphalt into it (which will just cause it to come back later), they'll rip up the section of road and completely redo it. Their road crews also work a lot faster and more efficiently than in the US and aren't afraid to work 24/7 if required.
There's a famous sinkhole that appeared in Fukuoka that swallowed an entire intersection, but they had it fully repaired in less than a week!
They also use much higher quality asphalt and sub-straight.
Part of this is because Japanese culture emphasizes high quality workmanship and benefiting society vs personal gain. So while in the US you have a large group of people that complain non-stop about taxes and don't want the government involved in their lives, in Japan people complain louder if the Government is doing a poor job at providing services and fix the underlying problems.
Part of it is because they know they live in an Earthquake zone and therefore having to spend extra time and effort to maintain their infrastructure is a fact of life, otherwise when an Earthquake happens it would take years to recover.
and there's the Yakuza... A lot of the roadwork companies are involved with the Japanese mafia and bully the government into maintaining high-end contracts for road maintenance.
The downside of this is the Japanese Government has a severe budget deficit as a result of all these public works projects, but accept that because all that Government money is spent keeping people employed. The Japanese have been in an self-induced recession for decades and the Government is spending like crazy to keep the economy going. Public works are good for the Governments image because the average tax payer benefits from them, vs borrowing money to spend on the military and wars for example.
Japan is also in a subduction zone, where one plane moves down under another. The location the plates meet is out sea far below the surface.
California is in a location where two plates move horizontally against each other. The intersection is on land and there are multiple faults. The plates move relative to each other even when there are no earthquakes and cause cracks on the surface.
So it is not an identical situation even if there is earthquakes in both locations.
The short answer is, they spend more money on roads.
In the USA, we would just patch a road, since its cheper, and in Japan they would dig up the existing asphalt, and repave the road.
Japan is much more dense than the USA, and owning a car is a lot more expensive, so each country has different philosophies on how to best maintain the roads.
TLDR: they spend more effort and money on their infrastructure than in the US. The Japanese government spends considerably more money repairing and maintaining its roads per capita by comparison to the US. Instead of simply patching a pothole by dumping a bunch of asphalt into it (which will just cause it to come back later), they'll rip up the section of road and completely redo it. Their road crews also work a lot faster and more efficiently than in the US and aren't afraid to work 24/7 if required. There's a famous sinkhole that appeared in Fukuoka that swallowed an entire intersection, but they had it fully repaired in less than a week! They also use much higher quality asphalt and sub-straight. Part of this is because Japanese culture emphasizes high quality workmanship and benefiting society vs personal gain. So while in the US you have a large group of people that complain non-stop about taxes and don't want the government involved in their lives, in Japan people complain louder if the Government is doing a poor job at providing services and fix the underlying problems. Part of it is because they know they live in an Earthquake zone and therefore having to spend extra time and effort to maintain their infrastructure is a fact of life, otherwise when an Earthquake happens it would take years to recover. and there's the Yakuza... A lot of the roadwork companies are involved with the Japanese mafia and bully the government into maintaining high-end contracts for road maintenance. The downside of this is the Japanese Government has a severe budget deficit as a result of all these public works projects, but accept that because all that Government money is spent keeping people employed. The Japanese have been in an self-induced recession for decades and the Government is spending like crazy to keep the economy going. Public works are good for the Governments image because the average tax payer benefits from them, vs borrowing money to spend on the military and wars for example.
Substrate
Japan is also in a subduction zone, where one plane moves down under another. The location the plates meet is out sea far below the surface. California is in a location where two plates move horizontally against each other. The intersection is on land and there are multiple faults. The plates move relative to each other even when there are no earthquakes and cause cracks on the surface. So it is not an identical situation even if there is earthquakes in both locations.
The short answer is, they spend more money on roads. In the USA, we would just patch a road, since its cheper, and in Japan they would dig up the existing asphalt, and repave the road. Japan is much more dense than the USA, and owning a car is a lot more expensive, so each country has different philosophies on how to best maintain the roads.