Studies on the June 23, 2010 north Ottawa M_W 5.2 earthquake and vicinity seismicity

摘要

The basic parameters for the earthquake with a moment magnitude (M _W) of 5.2 on the 23rd of June 2010 have been investigated. The earthquake occurred on a hidden fault in the northwest direction about 60 km north-northeast of Ottawa in the Western Quebec Seismic Zone (WQSZ) and had a focal depth of about 21 km. The focal mechanism was a thrust type with strike in the northwest direction and dipping in the northeast direction. The relative relocations of seven larger aftershocks show that the source rupture area was about 6 km2. The b value of the aftershock sequence was 0.8–1.0, and the decay rate of the aftershocks was faster than normal cases. The dominant seismogenic depths are about 12 to 22 km in most parts of the WQSZ, while the seismogenic depth along the Ottawa–Bonnechere Graben can be as deep as 28 km. Based on the seismic activity in the WQSZ and vicinity since 1961, it seems that the periods of moderate earthquakes are about 6–10 years.