Fig. 3From: Characteristics of the foreshock occurrence for Mj3.0 to 7.2 shallow onshore earthquakes in JapanAn example of earthquake swarm on December 18, 2009. The red circle is the mainshock, white circles are earlier earthquakes within 30 days and 30 km (most of them are within 1 day and 5 km), magnitudes are shown by the size of circles. This sequence includes 277 earlier earthquakes, which is an order of magnitude more than the typical foreshock occurrence levels which are usually 1 to 15 earthquakesBack to article page