Highlights:
The 2022 Mw 6.6 Menyuan earthquake was delayed due to the stress shadow
caused by historical earthquakes in northeastern Tibet.
The stress shadow covers the middle section of the Tianzhu Seismic Gap
and prohibits its seismic activity.
The eastern portion of the Tianzhu Seismic Gap was stress loaded by
historical earthquakes, indicating its increased seismic hazards.
Abstract: The 2022 Menyuan earthquake occurred in the
Qilian-Haiyuan fault system in northeastern Tibet. To investigate the
reason behind this earthquake and the seismic hazards of the Tianzhu
Seismic Gap, we demonstrated the spatiotemporal stress variation on the
fault system before and after 2022 through numerical modelling. We found
that the 2022 earthquake was delayed due to a stress shadow caused by
historical earthquakes. This stress shadow also covers the middle of the
Tianzhu Seismic Gap and prohibits its seismic activities to some extent.
Acting as a stress barrier to prevent the Tianzhu Seismic Gap rupturing
in one event, this stress shadow may decrease the possibility of
generating a future earthquake of magnitude more than Mw7.7 in this gap.
The east portion of the Tianzhu Seismic Gap was stress loaded,
indicating its increased seismic hazards. Attention should be paid to
the hazards prevention in the eastern portion of the gap.
Plain Language Summary: The 2022 Mw 6.9 Menyuan earthquake
occurred in the Qilian-Haiyuan fault system in northeastern Tibet. In
this study, we demonstrated the space-time stress variation along the
Qilian-Haiyuan fault system by calculating the stress change by several
large earthquakes in the target region in the past century. We found a
earthquake-induced stress shadow delayed the 2022 Menyuan earthquake.
The seismic activities in the middle section of the Tianzhu Seismic Gap
(to the east of the Qilian-Haiyuan fault system) are also prohibited by
the this stress shadow. However, the east portion of the Tianzhu Seismic
Gap was stress loaded by historical earthquake, indicating its increased
seismic hazards. More attention should be paid to the future seismic
hazards in the eastern portion of the Tianzhu Seismic Gap. It is helpful
for hazards prevention and disaster relief for the government of Gansu
province, China.
Keywords: The 2022 Menyuan earthquake, Tianzhu Seismic Gap,
Haiyuan fault, Stress shadow, Stress trigger