← Back to Sessions

Aftershock Regions of Mw > 6.7 Earthquakes on the Queen Charlotte–Fairweather Plate Boundary, 1929 to 2013

Description: 

For large, early-instrumental (pre-1960) earthquakes, the spatial region of aftershocks offers the best approximation for the rupture area of the mainshock. This link, introduced by Fedotov (1965) and Mogi (1968), was applied by Sykes (1971) to a large set of major earthquakes rupturing the northern Pacific plate boundary, from the westernmost Aleutians to south-central Alaska (1965, 1957, 1946, 1964) and along the Queen Charlotte-Fairweather (QCF) strike-slip fault system (1958, 1927, 1949). We recently relocated the historical aftershocks and updated the aftershock regions for the Aleutian-Alaska subduction zone (Tape and Lomax, 2022). Here we focus on the Mw > 6.7 earthquakes rupturing the QCF plate boundary. Using a probabilistic approach (NonLinLoc), we relocated 150 aftershocks arising from 11 mainshocks spanning from 1929-05-26 Ms 7.0 (northwest of Vancouver Island) in the south to 1979-02-08 Mw 7.4 (St. Elias Mountains) in the north. The analysis of the QCF aftershocks is much more difficult than the analysis of Aleutian-Alaska aftershocks because the mainshocks are smaller, resulting in fewer detectable aftershocks based on globally distributed recording stations. With fewer arrival times and aftershocks, the resulting relocations have higher uncertainties and pose challenges for establishing aftershock regions. Applying a similar approach to all 11 events (early-instrumental and modern), we establish revised aftershock regions, using the known plate boundary location for guidance. We compare our findings with previously published detailed studies dedicated to one or more of these earthquakes.

Session: Structure, Seismicity and Dynamics of the Queen Charlotte-Fairweather Fault System - I

Type: Oral

Date: 5/1/2024

Presentation Time: 04:30 PM (local time)

Presenting Author: Carl

Student Presenter: No

Invited Presentation: 

Authors