Albuquerque’s seismic category addresses the engineering demands of the Rio Grande Rift, where basin-edge effects and variable alluvial deposits can amplify ground motion beyond baseline assumptions. Our work applies IBC and ASCE 7 site classification under local amendments, with targeted soil liquefaction analysis to evaluate saturated sands along the floodplain, and site response analysis that captures impedance contrasts in the Santa Fe Group sediments. These studies translate regional seismicity into design spectra directly usable for structural compliance.
Critical infrastructure, mid‑rise buildings on deep fill, and healthcare facilities in Seismic Design Category C or D routinely require such evaluations. We integrate base isolation seismic design for essential projects where operational continuity governs, coupling ground-motion characterization with advanced structural protection to meet performance objectives under maximum considered earthquake shaking.
Seismic site assessment in Albuquerque addresses the evaluation of ground response under earthquake loading within the tectonically active Rio Grande Rift. The city's seismic hazard is shaped by the network of Quaternary rift faults, including the Sandia, Rincon, and Hubbell Spring faults, which traverse the metropolitan area. Local geology consists of deep, unconsolidated Santa Fe Group basin-fill sediments, primarily interbedded sands, silts, and gravels, which can amplify seismic waves and are susceptible to liquefaction in zones with a shallow groundwater table. A compliant investigation follows the International Building Code (IBC) as adopted by the City of Albuquerque, referencing ASCE 7 for seismic design parameters and site classification. Our work begins with targeted seismic investigation programs that integrate subsurface exploration with geophysical surveys to characterize these basin-fill deposits. Where near-surface conditions are critical, an exploratory test pit allows direct observation and sampling of stratigraphy and fault traces, providing essential data for paleoseismic interpretation and Vs30 profiling.
Subsurface characterization relies on rigorous in-situ testing methods calibrated to national standards. We execute the Standard Penetration Test (SPT) in accordance with ASTM D1586 to obtain split-spoon samples and N-values at regular intervals, forming the baseline for liquefaction triggering analyses per NCEER and Idriss & Boulanger methodologies. For fine-grained soils and precise modulus determination, we deploy the Ménard pressuremeter test (PMT) per ASTM D4719, which yields direct measurements of in-situ lateral stress, shear modulus, and deformation characteristics essential for advanced site response modeling. Complementary shear wave velocity profiling is conducted using downhole or crosshole seismic methods, while the Flat Dilatometer Test (DMT) following ASTM D6635 provides high-resolution stratigraphic profiling and estimates of constrained modulus and lateral stress index, refining site class determinations per ASCE 7-22 Chapter 20.
Typical Albuquerque projects requiring seismic analysis include essential facilities such as hospitals near the University of New Mexico, bridge foundations along the I-25 and I-40 corridors, and mid-rise structures in the downtown innovation district where Site Class D or E conditions predominate. The presence of shallow groundwater in the Rio Grande floodplain, particularly in the North Valley and Barelas neighborhoods, demands rigorous liquefaction potential index mapping and settlement estimation. For critical infrastructure, we supplement standard drilling with plate load tests (PLT) per ASTM D1194 to verify bearing capacity and modulus of subgrade reaction directly at foundation level, ensuring that ground improvement designs—such as stone columns or deep soil mixing—are validated under simulated seismic bearing pressures.
A complete seismic site characterization process delivers a geotechnical report with design ground motions, site coefficients Fa and Fv, liquefaction mitigation recommendations, and earth pressure diagrams for retaining structures. Deliverables include seismic hazard deaggregation, response spectra for the Maximum Considered Earthquake (MCE) and Design Earthquake, and explicit construction recommendations compliant with the New Mexico Commercial Building Code. By combining local fault knowledge with standardized in-situ testing—from the field density test using the sand cone method for compaction verification to high-end pressuremeter and dilatometer profiling—we provide a defensible basis for structural engineering decisions, reducing uncertainty in seismic demand and foundation performance across Albuquerque's variable basin-fill environment.