Each sensor of strong motion stations is labeled to identify installation place. There is a general labeling rule.
- A sensor installed on the ground will be labeled as 'GL'.
- A sensor installed on a floor of a building will be labeled as '##F'. ## indicates a ordinal number of the floor. For instance, '20F' is for a sensor on the 20th floor.
- A sensor installed on a basement floor of a building will be labeled as 'B#F'. # indicates a ordinal number of the basement floor. For instance, 'B2F' is for a sensor on the second basement floor. In some cases, there is only one basement floor , the ordinal number is omitted, like 'BF'.
- When there ae some sensors on the same floor, a letter will be added to its label. The letter may be one of E (east), W (west), N (north), S (south) and C (center). For instance, '10FS' is for a sensor on the south side of the 10th floor.
- A sensor installed in the ground will be labeled as 'G##'. ## indicates a depth of the sensor. For instance, 'G40' is for a sensor of 40 meters in the ground.
- When there are some sensors different points on/in the ground, other letters may be used than 'G'.
- There are exceptions as usual. The station CGC is a twin tower building with common lower floors. A sensor on the 20th floor of the tower B is labeled as 20B', and one on the 19th floor of tower C as '19C'. Another sensor on the common first floor is called '01F'. Sensors at the station ANX are labeled by more complicated rule.