Geology topics

Christodoulos Kyriakopoulos

Publications and source records attributed to Christodoulos Kyriakopoulos.

3 recordsLinked to original sources

USGS2025

Developing a probabilistic tsunami hazard assessment framework for Pacific sources: USGS Powell Center meeting summary

Multi-organizational principal investigators formed a U.S. Geological Survey (USGS) Powell Center Working Group (WG), Tsunami Source Standardization for Hazards Mitigation in the United States, to develop a comprehensive series of sources capable of generating tsunamis that could impact U.S. state and territory coastal areas using probabilistic tsunami hazard analysis (PTHA). PTHA results are commonly used to provide consistent tsunami hazard information for use in engineering and risk assessment and, to a lesser extent, hazard response planning. Following an initial weeklong planning meeting in April 2018, designed to establish the WG’s scope, a series of weeklong meetings devoted to aspects of tsunami hazards placed emphasis on assessment of various tsunami sources, including subduction zones in Alaska, the Atlantic and Caribbean, Cascadia, and the Pacific Basin, as well as landslides in Alaska, the Atlantic, and the Caribbean. The final meeting in the series discussed tsunami sources from crustal faults. These meetings, each with a regional geographic focus, were designed to incorporate reviews and feedback from subject matter experts (SMEs) in academia, private industry, and federal, state, and local governmental organizations. Incorporating consensus from SMEs is important because the results derived from the tsunami source models will be used to inform the public about potential hazards from tsunamis related to safety concerns. This paper describes the USGS Powell Center meeting in March 2023, devoted specifically to developing a PTHA for tsunami sources in the Pacific Ocean Basin other than the Alaska–Aleutian and Cascadia subduction zones that were addressed during previous WG meetings.

Environmental & Engineering Geoscience↗

USGS2024

Exploring the dynamic interactions between the Southern San Andreas Fault and a normal fault under the Salton Sea

We investigate the dynamic interactions between the Southern San Andreas Fault (SSAF) and a proximal normal fault (NF) beneath the Salton Sea in southern California. The NF, positioned near the SSAF terminus at Bombay Beach, exhibits 11–15 displacement events across 14 stratigraphic sequences, with a range of 0.2–1.4 m of vertical offset since ∼2–3 ka. Notably, four of these events may align temporally with SSAF earthquakes, raising questions about the possible interplay between the two faults. Utilizing dynamic rupture models, we analyze the coseismic interactions between the SSAF and NF, addressing under what conditions the SSAF induces slip on the NF. Our findings reveal that a suite of SSAF ruptures, particularly those propagating from north to south, can trigger slip on the normal fault and replicate observed vertical offsets. If the SSAF extends beneath the Salton Sea, earthquakes originating south of the NF intersection are less likely to trigger normal fault slip, although we cannot exclude this possibility. Some SSAF ruptures do not trigger discernible slip on the NF, rendering such events undetectable in the stratigraphic record. Our research contributes toward discussions regarding the seismic hazard in southern California, shedding light on the interplay between the SSAF and NF.

California↗

USGS2021

A geology and geodesy based model of dynamic earthquake rupture on the Rodgers Creek‐Hayward‐Calaveras Fault System, California

The Hayward fault in California's San Francisco Bay area produces large earthquakes, with the last occurring in 1868. We examine how physics‐based dynamic rupture modeling can be used to numerically simulate large earthquakes on not only the Hayward fault, but also its connected companions to the north and south, the Rodgers Creek and Calaveras faults. Equipped with a wealth of images of this fault system, including those of its 3D geology and 3D geometry, in addition to inferences about its interseismic creep‐rate pattern and rock‐friction behavior, we use a finite‐element computer code to perform 3D dynamic earthquake rupture simulations. We find that the rock properties affect the locations and amount of slip produced in our simulated large earthquakes. Crucial factors that control rupture behavior in our modeling are the earthquake nucleation locations, the fault geometry, and the data that reveal where the fault system is creeping or locked. Our findings suggest that large Rodgers Creek‐Hayward‐Calaveras‐Northern Calaveras (RC‐H‐C‐NC) fault‐system earthquakes may result from dynamic rupture that starts in a locked part of the fault system, but is then stopped by the creeping parts, leading to high‐magnitude‐6 earthquakes; or, from dynamic rupture that starts in a locked part of the fault system, then cascades through some of the creeping parts, leading to magnitude‐7 earthquakes.

California↗