There's more to the story than that.
The last German government before Merkel came to power, was a coalition between the Green party and the Social-Democrats (SPD), this government decided to phase-out nuclear power in Germany in favor of renewable energy by limiting the running time of existing nuclear power plants.
The next German government was a coalition between conservative CDU under Merkel and SPD, and the nuclear phase-out remained untouched.
But when Merkel won the federal elections a second time and was able to form a coalition with the Liberal-Democrats (FDP) replacing of the SPD as a coalition partner, who had voted in favor of the nuclear phase-out, they decided to cancel the nuclear phase-out.
This happened in the autumn of 2010 and was a controversial decision for the public opinion. When Fukushima happened half year later it was widely seen as a confirmation of the inherent risks of nuclear energy and thus the Green party’s energy politics, not because Germany is especially prone to Tsunamis, but because it showed that it's impossible to rule out and plan for every possible dangerous situation in advance, and that even a high-tech country like Japan, on a comparable technical level to Germany, was not able to stop the meltdowns.
Elections in federal states shortly after Fukushima resulted in a landslide loss for Merkel's CDU and big wins for the Green party, the CDU losing one of its stronghold states [1] it had before held constantly for 58 years.
As far as I remember Merkel foresaw the public reaction and almost immediately after Fukushima voiced out in favor of reversing the cancelation of the nuclear phase-out, but could only get a solid backing in her party, after the losses in the federal state elections.
[1] https://www.swissinfo.ch/ger/-fukushima-strahlt-bis-baden-wu...
