In volcano seismology, a term sometimes applied to long-period (LP) volcanic earthquakes with an especially monochromatic coda reminiscent of the profile of a screw (from the Spanish for screw). See McNutt (2002, Figure 4)
Peter Bormann, Keiiti Aki, William H. K. Lee, and Johannes Schweitzer (Compilers and Amenders), Glossary of Terms Interest to Earthquake and Engineering Seismologists (Version 1), Publication records from external use of GFZ scientific infrastructure, Germany 2011. http://gfzpublic.gfz-potsdam.de/pubman/item/escido c:56137:3/component/escidoc:56143/Glossary_rev1.pd f, (ND/ Erthq - Amer) {980}