Seismic array classified until the 1990s. Today they become part of the IMS as primary or auxiliary stations. Seismic arrays are not only used to monitor earthquakes and nuclear tests, but also used as a tool for investigating nature and source regions of microseisms as well as locating and tracking volcanic tremor and analyzing complex seismic wave-field properties in volcanic areas. Seismic arrays can be classified by size, which is defined by the array's aperture given by the largest distance between the single seismometers. The sensors in a seismic array are arranged in different geometry patterns horizontally. The arrays built in the
Venus effect viewers see is different from what the actor sees, because the camera is not right behind the actor, but the position of the actor is often chosen so that his or her image is nicely framed in the mirror for the camera. Although the name of the effect refers to a woman, Venus, the effect is more general. The effect is seen with an animal apparently looking at itself in a mirror in "The Lady and the Unicorn" (French: "La Dame à la licorne") tapestries, where the unicorn appears to be gazing at its own reflection as it kneels on