Chukwuebuka C Nweke

University of Southern California | USC · Department of Civil and Environmental Engineering

This study was motivated by the difficulty in determining the resilient modulus of soils using the repeated load triaxial test (RLTT) recommended by the mechanistic-empirical pavement design guide (MEPDG). An alternative means to estimate the resilient modulus of fine-grained soils has been established in the form of three models that were develope...

Site response in sedimentary basins is partially governed by mechanisms associated with three-dimensional features. This includes the generation of propagating surface waves due to trapped and refracted seismic waves, focusing of seismic energy due to basin shape and size, and resonance of the entire basin sediment structure. These mechanisms are r...

This repository captures some of the images and damage conditions identified by the StEER VAST while scanning social media and other online sources after the Mw 5.6 Indonesia Earthquake, 2022 Nov 21. The examples included in these slides augment what is presented in the joint PVRR report for this event (DesignSafe Project PRJ-3781). None of the...

The first product of StEER’s Level 1 response to the M5.6 Indonesia Earthquake is this Preliminary Virtual Reconnaissance Report (PVRR), which is intended to: (1) provide details of the November 22 M 5.6 earthquake, (2) summarize the tectonic features of the event, (3) synthesize the recording ground motions and provide comparisons with design-leve...

Ergodic site amplification models for active tectonic regions are conditioned on the time-averaged shear wave velocity in the upper 30 m ( V S 30 ) and the depth to a shear wave velocity isosurface ( z x ). The depth components of such models are derived using data from sites within many geomorphic domains. We provide a site amplification model uti...

We introduce procedures to validate site response in sedimentary basins as predicted using ground motion simulations. These procedures aim to isolate contributions of site response to computed intensity measures relative to those from seismic source and path effects. In one of the validation procedures, simulated motions are analyzed in the same ma...

Systematically collected and curated data sets from historical events provide a strong basis for simulating the physical and functional effects of natural hazards on the built environment. This article develops a relational database to support post-earthquake damage and recovery modeling of building portfolios. The current version of the database h...

Coseismic surface fault displacement presents a serious potential hazard for structures and for lifeline infrastructure. Distributed lifeline infrastructure tends to cover large distances and may cross faults in multiple locations, especially in active tectonic regions like California. However, fault displacement measurements for engineering applic...

The adoption of mechanistic-empirical approach to pavement design requires the use of resilient modulus of subgrade soils as a crucial input. The determination of in the laboratory is inexpedient due to the nature of the existing test protocols. This prompted the use of estimated values, which inadvertently has gained popularity lately. However, th...

Seismic site response can be influenced by a variety of physical mechanisms that include amplification due to resonance, nonlinearity, topographic effects, impedance contrasts, and contributions from two- or three-dimensional wave propagation in sedimentary basins. Current ground motion models use ergodic procedures that average these effects over...

The 2019 Ridgecrest earthquake sequence produced a 4 July M 6.5 foreshock and a 5 July M 7.1 mainshock, along with 23 events with magnitudes greater than 4.5 in the 24 hr period following the mainshock. The epicenters of the two principal events were located in the Indian Wells Valley, northwest of Searles Valley near the towns of Ridgecrest, Trona...

We present a database and analyze ground motions recorded during three events that occurred as part of the July 2019 Ridgecrest earthquake sequence: a moment magnitude (M) 6.5 foreshock on a left-lateral cross fault in the Salt Wells Valley fault zone, an M 5.5 foreshock in the Paxton Ranch fault zone, and the M 7.1 mainshock, also occurring in the...

Following the Ridgecrest earthquake sequence, consisting of an M 6.4 foreshock and M 7.1 mainshock along with many other events, the Geotechnical Extreme Events Reconnaissance association deployed a team to gather perishable data. The team focused their efforts on documenting ground deformations including surface fault rupture south of the Naval Ai...

The ability to rapidly assess the spatial distribution and severity of building damage is essential to post-event emergency response and recovery. Visually identifying and classifying individual building damage requires significant time and personnel resources and can last for months after the event. This paper evaluates the feasibility of using ma...

The Ridgecrest Earthquake sequence included a foreshock event on July 4 2019 (M6.4) and a M7.1 mainshock event on July 5 2019. These events occurred in the Eastern California Shear Zone, near Indian Wells Valley, south of China Lake and west of Searles Valley. GEER has partnered with several organizations to collect perishable data and document the...

We investigate benefits of regionalizing basin response in ergodic ground motion models. Using southern California data, we find average responses between basin structures, even when the primary site variables used in ground motion models (VS30 and depth parameters) are controlled for. For example, the average site response in relatively modestly s...

The establishment of the bio-inspired and bio-mediated sub-disciplines in the emerging field of biogeotechnology has led to the developments of many innovative methods and techniques. These methods and techniques potentially provide sustainable alternatives to conventional approaches that may be less desirable due to their use of high-embodied ener...

Over the past decade, recent developments between the geotechnical and life science disciplines have establish microbial induced calcite precipitation (MICP) as a novel ground improvement method. This method improves the static and dynamic mechanical properties of the soil while maintaining its environmentally friendly characteristics. Its applicat...