The SPT hammer drops 760 mm. The sampler drives into Athlone ground. We count the blows. That N-value is our first real look at liquefaction susceptibility. At our lab, analysis starts with field penetration data — SPT N1,60 or CPT tip resistance — run through the NCEER (Youd & Idriss 2001) framework. For Athlone, a town built on River Shannon floodplain deposits and glacial sands, the water table sits high. That changes everything. Fine sand with silt layers, saturated since October rains, can lose strength fast under seismic shaking. We combine field testing with MASW to get shear wave velocity profiles, then cross-check against CPT testing where access allows. The output is not a generic report. It is a site-specific factor of safety against liquefaction at each critical depth.
Liquefaction is not just a seismic problem. In Athlone the high water table in winter means saturated granular soils are primed for strength loss even under moderate shaking.
Service characteristics in Athlone
Demonstration video
Risks and considerations in Athlone
The Athlone area is underlain by Dinantian limestone with overlying glacial and alluvial deposits. Along the Shannon and into the callows, you hit soft silts and loose fine sands within 3 to 5 meters of surface. Water table in winter is less than 2 meters deep. Under seismic loading — even a magnitude 4.5 event at 30 km — these saturated granular units can liquefy. The risk is differential settlement under foundations, lateral spreading toward the river channel, and flotation of buried tanks. We have seen borehole data from the west side industrial estates where N-values drop below 5 blows in the top 4 meters. That is textbook liquefiable material. If you are putting in a pile foundation, liquefaction-induced loss of skin friction in the upper layers must be accounted for. Ignoring it means designing for a soil that will not be there during the earthquake. Eurocode 8 Part 5 (EN 1998-5:2004) requires this check for all sites in ground types D and E.
Our services
We deliver the full liquefaction assessment package. Fieldwork runs first — drilling, sampling, CPT or MASW. Then lab tests on recovered samples. Then analysis and reporting. Two core services cover the typical request in Athlone.
Liquefaction Screening & Analysis
SPT-based or CPT-based assessment using NCEER simplified procedure. Includes CSR/CRR calculation at each test depth, factor of safety profile, and post-liquefaction settlement estimate. We deliver a report with depth plots and recommendations per Eurocode 8.
Geophysical Liquefaction Assessment
MASW survey for Vs30 and Vs1 profiles. Site classification per EN 1998-1. Liquefaction potential index (LPI) mapping across the site. Best for large sites where you need continuous coverage between boreholes.
Frequently asked questions
How much does a liquefaction analysis cost for a site in Athlone?
A full SPT-based liquefaction assessment with 2 to 3 boreholes typically ranges from €2.530 to €3.980. The final figure depends on access conditions, depth of investigation, and whether you need CPT or MASW on top. We give a fixed quote after reviewing your site plan and ground conditions.
Is Athlone at risk of earthquakes strong enough to cause liquefaction?
Ireland has low seismicity but not zero. The Irish National Seismic Network records small events regularly. For Athlone, the risk scenario is a moderate earthquake at shallow depth with PGA reaching 0.02g to 0.04g on soft soil sites. Combined with the high water table and loose alluvial sands along the Shannon, that is enough to trigger liquefaction in the upper 4 to 5 meters. Eurocode 8 requires consideration for all structures in consequence class CC2 and above.
What field tests do you need to run the analysis?
SPT with energy correction is the baseline. We need N-values every 1.5 meters and soil samples for fines content and gradation. CPT gives a continuous profile and is better for detecting thin liquefiable layers. MASW adds shear wave velocity, which helps on sites where you cannot drill easily. Often we combine two methods for a more solid CRR estimate.
How long does it take to get the liquefaction report?
Fieldwork typically takes 1 to 2 days. Lab tests on samples run 5 to 7 working days. Analysis and report writing add another 3 to 4 days. You can expect the final report in about two weeks from mobilization. We can speed up the lab and analysis phases if the project schedule demands it.