SiteAmp
To build SiteAmp, Temblor assembled the largest possible global dataset of in situ vs30 observations (‘vs30’ is the shear wave velocity over the uppermost 30 m) to build a training set. This includes 4,500 observations from the United States, and 10,000 observations from Chile, Israel, New Zealand, Mexico, Europe. Databases from the USGS and PEER (Pacific Earthquake Engineering Research Center), were incorporated. We then used a high-resolution digital elevation model, with buildings removed, as the basis of the model. SiteAmp thus uses elements of relief, such as slope, elevation, and spatial derivatives of these quantities. SiteAmp has a 100 m resolution worldwide, which, as far as we know, is the highest spatial resolution model that is commercially available.
Comparison of SiteAmp (100 m resolution) with the USGS model (750 m resolution).
The Temblor client, Fermat Capital Management, conducted an independent test of SiteAmp. They calculated the predicted shaking at 32,000 seismometers in Japan (Shindō JMA intensity meters) for the past 25 years, correcting the predicted shaking for site amplification using SiteAmp, and also using the USGS model, and then compared both to the recorded shaking. They found that SiteAmp outperformed the USGS amplification model. Because of nearest- neighbor smoothing, their test did not take full advantage of the higher resolution of SiteAmp, and yet it nevertheless exceeded the reference model.
The 2023 M 7.8 2023 Kahramanmaraş, Türkiye, earthquake collapsed 35,000 buildings. These collapses were logged from satellite imagery by Humanitarian OpenStreetMap teams. Temblor’s SiteAmp correlates with this heretofore unmatched record of extreme damage.
Comparison of the observed and modeled Vs30 values in northern Taiwan shows good general agreement, particularly in the populated basins.
SiteAmp reveals areas of likely extreme shaking amplification in large earthquakes, such as Oxnard, Marina Del Rey, Newport Beach, and Coachella. Strong amplification is also expected in San Bernardino, and in the San Fernando Valley northwest of the Los Angeles Basin, and the Pasadena area northeast of the L.A. basin.
