Task: Question Answering
Input (English): Context: BEIJING - Astronomers have defended against rumors that the terrible earthquake and the following tsunami in Japan were closely related to or even caused by the "supermoon" that will appear in the sky on Saturday. The word "supermoon" was introduced in a report by the British newspaper Daily Mail on March 9, which said amateur scientists were warning that such an astronomical phenomenon could disturb the Earth's climate patterns and may even cause earthquakes and volcanic activity. The moon will be 356,577 kilometers from the Earth on Saturday, the closest in 19 years, and the closest point in its oval orbit coincides with a full moon, the report said. However, Saturday's moon is not actually the closest to Earth in 19 years, Tang Haiming, an astronomer with Shanghai Astronomical Observatory under the Chinese Academy of Sciences, told Xinhua News Agency. A shorter distance of 356,570 km between the two bodies was reached in January 2005, and a distance of 356,566 km was seen in December 2008. Yet some people suggest that previous supermoons have occurred prior to extreme weather events. In 1974 the phenomenon was followed by Cyclone Tracy in Darwin, Australia, and in 2005 it occurred shortly before a deadly tsunami in Indonesia. Coincidentally, two fresh disasters happened in Asia right before Saturday's supermoon. The public's concern about their connection with the moon boomed after Japan's terrible earthquake and tsunami and an earthquake in Southwest China's Yunnan province that killed 25 people on March 10. But astronomers are trying to _ people that such rumors are merely unreasonable. "A supermoon could cause high tides but has no direct relation with natural disasters such as earthquakes," Liu Jie, a researcher with the China Earthquake Network Center, told China Daily on Tuesday. "We can't find any necessary connection between previous supermoons and earthquakes. And the quake in Japan occurred because the Earth's inner energy had accumulated to some extent, and it's not related to the moon. " he said. James Garvin, chief scientist at the Goddard Space Flight Center under NASA, said in an article on NASA's website that "the effects on Earth from a supermoon are minor.""The combination of the moon being at its closest to Earth in its orbit, and being in its 'full moon' configuration ( to the Earth and sun), should not affect the inner energy balance of the Earth, since there are lunar tides every day. " Zhu Jin, curator of the Beijing Planetarium, said"the moon moves around the earth in a certain path, so each orbit has a perigee - its closest approach, and an apogee - its furthest distance.""A lunar perigee occurs once a month and there are very small differences in distances between perigees,"he said."Those tiny differences are far from enough to cause earthquakes or eruption of a volcano,"he added. 
 Question: What's the real reason for the quake in Japan?
Output (English): because the earth's inner energy had accumulated to some extent.