the volcano in the weeks leading up to the eruption was acknowledged in 1981 in a chronology of the eruption, published as part of the USGS report titled 'The 1980 Eruptions of Mount St. Helens, Washington': Since Johnston's death, his field of volcanic eruption prediction has advanced significantly, and volcanologists are now able to predict eruptions based on a number of precursors that become apparent between days and months in advance. Geologists can now identify characteristic patterns in seismic waves that indicate particular magmatic activity. In particular, volcanologists have used deep, long-period earthquakes that indicate that magma is rising through the crust. They can also use carbon dioxide emission as a proxy for magma supply rate. Measurements of surface deformation due to magmatic intrusions, like those that were conducted by Johnston and the other USGS scientists at the Coldwater I and II outposts, have advanced in scale and precision. Ground deformation monitoring networks around volcanoes now consist of InSAR (interferometry), surveys of networks of GPS monuments, microgravity surveys in which scientists measure the change in gravitational potential or acceleration because of the intruding magma and resulting deformation, strain meters, and tiltmeters. Though there is still work to be done, this combination of approaches has greatly improved scientists' abilities to forecast volcanic eruptions. In addition to his work, Johnston himself has become part of the history of volcanic eruptions. With Harry Glicken, he is one of two volcanologists from the United States to die in a volcanic eruption. Glicken was being mentored by Johnston, who relieved Glicken of his watch at the Coldwater II observation post 13 hours before Mount St. Helens erupted. Glicken died in 1991, eleven years later, when a pyroclastic flow overran him and several others at Mount Unzen in Japan. Commemoration Early acts of commemoration included two trees that were planted in Tel Aviv, Israel, and the renaming of a community center in Johnston's hometown as the "Johnston Center". These actions were reported in newspapers during the first anniversary of the eruption in May 1981. On the second anniversary of the eruption, the USGS office in Vancouver (which had been permanently established following the 1980 eruption) was renamed the David A. Johnston Cascades Volcano Observatory (CVO) in his memory. This volcano observatory is the one most responsible for monitoring Mount St. Helens, and helped to predict all of the volcano's eruptions between 1980 and 1985. In a