Surface deformation and fault displacement associated with an earthquake swarm in Iceland

ABSTRACT Understanding fault rupture deformation patterns, especially in complex fault zones, has fundamental implications on seismotectonic studies and hazard mitigation for the built environment. The 2019 Mw 6.4 and Mw 7.1 Ridgecrest earthquake ruptures offer an opportunity to quantify deformation patterns and surface displacements from a complex fault rupture. Our field reconnaissance, within 18 hr of the Mw 6.4 event, documented a complex and relatively broad fault deformation zone up to a few kilometers wide in the vicinity of a gas transmission pipeline intersected by the surface rupture south of Highway 178. The subsequent Mw 7.1 event resulted in similarly distributed surface fault deformation within a broad zone that crossed a second gas transmission pipeline located south of Highway 178. On 10 July, fault-normal pipeline assessment trenches were excavated at both locations and provided evidence for late Pleistocene fault rupture on both faults expressed as upward fault truncations and paleoliquefaction features. Subsequent imagery-based rupture-mapping facilitated identification and measurement of offset features that were not identified during field mapping. Fault displacement measurements document a gradual decrease in fault slip on rupture southwestward from the Mw 6.4 epicenter within the study area. However, displacement along the primary Mw 7.1 rupture decreased more drastically southeastward toward a structural complexity at a fault stepover expressed as a horsetail splay. Fault-normal slip distributions showed that majority of the surface deformation was accommodated along discrete fault strands within the primary fault zone across both ruptures. This work expands the catalog of high-fidelity coseismic rupture information used to better understand seismotectonic processes, while contributing to refinement of fault displacement models used in support of critical infrastructure design.

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Surface Faulting and Ground Deformation: Considerations on Their Lower Detectable Limit and on FDHA for Nuclear Installations

Earthquake Spectra ◽

10.1193/110718eqs253m ◽

2019 ◽

Vol 35 (4) ◽

pp. 1821-1843

Author(s):

Leonello Serva ◽

Franz A. Livio ◽

Aybars Gürpinar

Keyword(s):

Nuclear Power ◽

Power Plants ◽

Surface Deformation ◽

Limit Of Detection ◽

Ground Deformation ◽

Hazard Analysis ◽

Threshold Value ◽

Data Set ◽

Significant Regression ◽

Fault Displacement

We performed a review of a representative data set on coseismic surface deformation, derived from both interferometric synthetic aperture radar imaging and from a traditional field survey of surface faulting. This analysis indicates a minimum threshold value of M w 5.4–5.5 for earthquake-induced ground deformation and faulting, with an inherently lower limit of detection that makes it hard to recognize surface deformation caused by M w < 4.5–5.0 events. Significant exceptions are represented by shallow (i.e., less than circa 5 km) events that occur in volcano-tectonic settings, where surface deformation and dislocation are also clearly detectable for M w circa 4.0. Furthermore, a statistically significant regression between the areal extent of surface deformation and maximum slip at surface is proposed. This correlation is discussed in relation to fault displacement hazard analysis for nuclear power plants. In particular, the deformation area is used to find a potential solution for the second and third criterion for defining a capable fault.

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Surface deformation associated with the March 1996 earthquake swarm at Akutan Island, Alaska, revealed by C-band ERS and L-band JERS radar interferometry

Canadian Journal of Remote Sensing ◽

10.5589/m04-054 ◽

2005 ◽

Vol 31 (1) ◽

pp. 7-20 ◽

Cited By ~ 28

Author(s):

Zhong Lu ◽

Charles Wicks Jr. ◽

Ohig Kwoun ◽

John A Power ◽

Daniel Dzurisin

Keyword(s):

Surface Deformation ◽

Earthquake Swarm ◽

Radar Interferometry ◽

L Band

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A Worldwide and Unified Database of Surface Ruptures (SURE) for Fault Displacement Hazard Analyses

Seismological Research Letters ◽

10.1785/0220190144 ◽

2019 ◽

Vol 91 (1) ◽

pp. 499-520 ◽

Cited By ~ 7

Author(s):

Stéphane Baize ◽

Fiia Nurminen ◽

Alexandra Sarmiento ◽

Timothy Dawson ◽

Makoto Takao ◽

...

Keyword(s):

Land Use Planning ◽

Active Fault ◽

Surface Deformation ◽

Original Data ◽

Implementation Effort ◽

Critical Facilities ◽

The Status ◽

Open Access Database ◽

Surface Ruptures ◽

Fault Displacement

Abstract Fault displacement hazard assessment is based on empirical relationships that are established using historic earthquake fault ruptures. These relationships evaluate the likelihood of coseismic surface slip considering on‐fault and off‐fault ruptures, for given earthquake magnitude and distance to fault. Moreover, they allow predicting the amount of fault slip at and close to the active fault of concern. Applications of this approach include land use planning, structural design of infrastructure, and critical facilities located on or close to an active fault. To date, the current equations are based on sparsely populated datasets, including a limited number of pre‐2000 events. In 2015, an international effort started to constitute a worldwide and unified fault displacement database (SUrface Ruptures due to Earthquakes [SURE]) to improve further hazard estimations. After two workshops, it was decided to unify the existing datasets (field‐based slip measurements) to incorporate recent and future cases, and to include new parameters relevant to properly describe the rupture. This contribution presents the status of the SURE database and delineates some perspectives to improve the surface‐faulting assessment. Original data have been compiled and adapted to the structure. The database encompasses 45 earthquakes from magnitude 5–7.9, with more than 15,000 coseismic surface deformation observations (including slip measurements) and 56,000 of rupture segments. Twenty earthquake cases are from Japan, 15 from United States, two from Mexico, Italy, and New Zealand, one from Kyrgystan, Ecuador, Turkey, and Argentina. Twenty‐four earthquakes are strike‐slip faulting events, 11 are normal or normal oblique, and 10 are reverse faulting. To pursue the momentum, the initial and common implementation effort needs to be continued and coordinated, and the maintenance and longevity of the database must be guaranteed. This effort must remain based on a large and open community of earthquake geologists to create a free and open access database.

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