The volcano on the stamps' central oval design is an allegorical representation of the coat of arms existing at the time; the stamps depict the Izalco volcano, popularly known as "El Faro del Pacífico" - "The Lighthouse of the Pacific". This argument is based on the fact that the decree signed by Francisco Duenas , creating the coat of arms, specifically mentions the Izalco volcano as the inspiration for its design,  and also on the idea that the Izalco volcano was (and still is) one of the symbols of the country. Covers genuinely used with these stamps are rare. So far, only 37 have been recorded.    
The current seismic network is composed of 11 stations linked to RVO by UHF or VHF radio telemetry, with USGS-made modulators and demodulators. 10 stations are located around Rabaul, including one at RVO, and use Mark Products seismometers (8 vertical L4 and 2 three-component L22). The other station is located 25 km E of the caldera and has an electronically simulated Wood-Anderson horizontal seismometer, recorded on Helicorders at RVO at three different gain steps, for magnitude determination. In addition, a 2-component horizontal " Omori " mechanical seismograph is still in use at RVO, as a strong motion instrument. The signals from all the Rabaul stations are recorded on the IASPEI PC-QUAKE data acquisition system. All vertical seimometers are also recorded on Helicorders, equipped with in-house designed enhancers, and are also monitored using RSAM and SSAM. P and S arrivals are picked interactively, using XPLAY and epicenters are determined with Hypo-71. The velocity model currently in use was shown to be deficient, and plans are being drawn to determine a new model.