Coast of British Columbia and south eastern Alaska are frequently hit by strong earthquakes originating from a complex system of faults that give high magnitude shakes. The close examination of the two most recent major events - the Mw 7.8 Haida Gwaii and Mw 7.5 Craig events - revealed valuable information with regards to the interaction between the Pacific and North America plates and the fault complexity of the region. All research findings are included in 19 technical articles of a special issue published by the Seismological Society of America.
The two events occurring in 2012 and 2013 released a great amount of strain that has been building up for years in the fault system, but left the Queen Charlotte Fault - a strike slip fault very similar to the San Andreas fault in California - untouched. Before the 2012 event, the Queen Charlotte Fault was considered to be the prevailing tectonic structure in the area, a belief that was overruled after the 2012 events. In addition, careful examination of the Haida Gwaii mainshock by Kao et al. proved the previously suspected subduction activity in the area, after showing the slid at a low angle of the Pacific plate below the North American plate along a thrust fault.
Another group of scientists (Nykolaishen et al.) managed to locate the earthquake's rupture offshore to the west of Haida Gwaii and not in the islands based on GPS observations, while James et al. - in their introductory message of the special issue - indicate that the 2012 rupture and the northwest directivity of ground motion may have affected the occurrence time of the 2013 Graig event. University of Alaska Fairbanks scientists S. Holtkamp and N. Ruppert after examining 1785 aftershocs following the Craig sequence concluded that the mixed faulting behavior is an indication that the region is still in a state of transpression, stating that the plates are both sliding with reference to each other and colliding at an angle.
The special issue appearing online this April and in print in May, focuses upon three main themes: the regional tectonic framework and the nature of the Pacific and North America plate interaction at the Queen Charlotte Fault zone, the Craig earthquake and the Haida Gwaii event.
Source: ScienceDaily
The international team of scientists just finished exploring the seabed of the Pacific Ocean, offsho...
The total number of major active faults in the country has now increased to 113, as the Headquarters...
According to a new study, a fault previously considered as dormant may cause a Mw 6.4 earthquake in...
Satellite data of the last to decades, helped in mapping the land creep along the Calaveras and the...
Although earthquakes along the North Anatolian Fault (NAF) have been very frequent and devastating t...
The Genoa fault was exposed by mining works of a quarry. The fault was found between a thick sedime...
A massive M 7.8 earthquake that hit off the coast of Alaska, forced authorities to issue a tsunami...
A tsunami warning was issued after a powerful earthquake hit Alaska's southern coast. The M 7.5...
The earthquake was one of the deadliest to ever strike the country The earthquake was one of the...