南關東今後四年內有七成機會發生七級地震?

Recently the Mainichi News on-line reported the following:
南関東でマグニチュード（Ｍ）７級の地震が今後４年以内に７０％の確率で発生する可能性があるとした平田直・東京大地震研究所教授らの研究チームの試算について、国の地震調査委員会は９日、「精度が低い」として、「今後３０年以内の発生確率は７０％」としている従来の長期予測は変更しないとの見解を示した。
　平田教授らの試算は、東日本大震災後に関東地方で増加したＭ３以上の地震の発生数を基に確率を割り出した。これに対し、地震調査委は「数える地震の規模や、発生領域の設定によって確率は大きく変動するため、誤差が大きい」とした。地震調査委の阿部勝征委員長は「３０年以内で７０％も切迫している状況には違いない」と述べた.
(試譯文)
Regarding the trial calculation made by the research team of professor Naoshi Hirata and others from the University of Tokyo earthquake research institute which presupposed that there might be a 70% probability that a magnitude (M)7 earthquake might occur in south Kanto within four years from now, on the 9th the Earthquake Research Committee of the country saw it as "having low accuracy", and expressed the view that the conventional long-term forecast which supposed that "the occurring probability within 30 years will be 70% from now on" had not changed.
Professor Hirata and the team's trial probability calculation was generated on the basis of the increased number of the earthquake beyond M3 occurred after the East Japan great earthquake in the Kanto district. On the other hand, the Earthquake Investigation Committee presupposed that "with regard to the base of the setting, because it counts the size of the earthquake and the region of occurrence, it could change greatly, and the chance for error is high". Katsuyuki Abe the chairman of the Earthquake Investigation Committee said, "There is no difference from a 70% chance of having an impending situation within the coming 30 years".

Many Japanese are worrying about another big earthquake at South Kanto