預警系統
The Earthquake Early Warning system was activated upon the detection of primary waves – seismic waves that forego an earthquake's perceivable ground motions – giving residents 6.8 seconds to seek cover before the main shock. At the risk of a tsunami – which reach their destructive wave heights near shallow coastal waters – local fishing boats along coastlines were shown heading out to sea on national news broadcasts. A warning for a localised tsunami of up to was issued by the Japan Meteorological Agency; however, no significant waves were recorded, and the warning was cancelled soon thereafter. In response to the earthquake, the fire department dispatched search and rescue teams and emergency crews for relief efforts and damage assessments throughout the affected area. Six medical crews in pairs of two were also sent to Kanagawa, Chiba and Gunma prefectures. Former Prime Minister Naoto Kan postponed a press conference scheduled for 17:50 JST marking the one-month anniversary of the catastrophic Tōhoku earthquake and tsunami.