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Table 1 A summary of recommendations from SESAME guidelines (Bard and the WG 2004)

From: Lessons from April 6, 2009 L’Aquila earthquake to enhance microzoning studies in near-field urban areas

Type of parameterMain Recommendations
Recording durationMinimum expected f0(Hz)Recommended minimum recording duration (min)
Measurement spacingMicrozonation: start with a large spacing and, in case of lateral variation of the results, densify the grid point.
Single site response: never use a single measurement point to derive f0 value, make at least three measurement points.
Recording parametersLevel the sensor as recommended by the manufacturer.
Fix the gain level at the maximum possible without signal saturation.
In situ soil-sensor couplingSet the sensor down directly on the ground, whenever possible.
Avoid setting the sensor on “soft grounds” (mud, plowed soil, tall grass, etc.) or soil saturated after rain.
Artificial soil-sensor couplingAvoid plates from “soft” materials such as foam rubber, cardboard, etc.
On steep slopes that do not allow correct sensor leveling, install the sensor in a sand pile or in a container filled with sand.
On snow or ice, install a metallic or wooden plate or a container filled with sand to avoid sensor tilting due to local melting.
Nearby structuresAvoid recording near structures such as buildings, trees, etc. in case of wind blowing (faster than about 5 m/s). It may strongly influence H/V results by introducing some low frequencies in the curves.
Avoid measuring above underground structures such as car parks, pipes, sewer lids, etc.
Weather conditionsWind: protect the sensor from the wind (faster than approx. 5 m/s). This only helps if there are no nearby structures.
Rain: avoid measurements under heavy rain. Slight rain has no noticeable influence.
Temperature: check sensor and recorder manufacturer’s instructions.
Meteorological perturbations: indicate on the field sheet whether the measurements are performed during a low-pressure meteorological event.
DisturbancesMonochromatic sources: avoid measurements near construction machines, industrial machines, pumps, generators, etc.
Transients: in case of transients (steps, cars, etc) increase the recording duration to allow for enough windows for the analysis, after transient removal.