← Back to Sessions

Assessing Distribution and Pattern of the Earthquake-Related Deformation Caused by Large Continental Normal Earthquakes Using Optical Image Correlation

Description: 

Earthquakes on normal faults in the continental setting are relatively uncommon. The scarcity of surface-rupturing events underpins an absence of surface displacement measurements. It is a common practice to use surface offset as a proxy to understand the fault structure at depth. Hence, the lack of comprehensive surface data impedes the subsurface reconstruction of seismogenic normal faults and prohibits the thorough assessment of earthquake hazards. To supplement the available surface displacement measurements and to make statistically significant inferences, we apply optical image correlation (OIC) methods to historical images from three large continental normal earthquakes in the western United States (1954 Dixie Valley (Mw 6.8) - Fairview Peak (Mw 7.1) earthquake sequence, the 1959 Mw 7.2 Hebgen Lake earthquake and the 1983 Mw 6.9 Borah Peak earthquake). The results of this study are displacement maps with three components of deformation from which we extract high-resolution 3-d measurements everywhere along the surface rupture.

In this work, we quantify surface offset, fault zone width, and percentage of off-fault deformation. These parameters are used as a proxy to understand the subsurface geometry and structure of the fault. Our data confirm behaviours previously observed along strike-slip faults (e.g. magnitude of off-fault deformation is proportional to the rupture complexity). In addition, a comparative assessment of the results from the three study areas demonstrates that features such as excess slip detected close to the fault scarp are not unique and can be found along multiple dip-slip faults. Consequently, this study documents the variation of the quantifiable parameters along the normal faults. It suggests that while some parameters are a universal reflection of the fault characteristics, others vary according to the geology or topography in the area and should not be accepted without further investigation.

Session: From Earthquakes to Plate Boundaries: Insights Into Fault Behavior Spanning Seconds to Millennia

Type: Oral

Date: 4/20/2023

Presentation Time: 04:30 PM (local time)

Presenting Author: Lucia Andreuttiova

Student Presenter: Yes

Invited Presentation: Yes

Authors