The second volume of a two-volume series dealing with the topic of acoustic emission /microseismic (AE/MS) activity. Over the last 50 years a wide range of field and laboratory studies, by a variety of researchers, have verified that when stressed or deformed most solids emit low-level seismic signals. Such AE/MS signals are commonly observed in rocks and soils, and have formed the basis of a unique tool for the investigation of the stability and general mechanical behavior of such materials, both in the field and the laboratory. The first volume of this series deals primarily with basic material behavior, stress wave propagation, transducer design and installation, electronic instrumentation, signal processing, and data acquisition and analysis. In contrast, the second volume deals specifically with the use of AE/MS techniques in a variety of geotechnical field and laboratory applications. Geotechnical field applications discussed in Part I of volume 2 include, slope stability, underground mines, underground storage, and a wide range of miscellaneous field applications. These include: dams, tunnels, caverns, subsidence, rock drilling and cutting, grout monitoring, and fluid leakage. Where possible, detailed information on general field techniques, AE/MS instrumentation, and monitoring and data processing procedures are included. Part II of volume 2 deals with a wide range of AE/MS laboratory studies carried out on geologic materials. These include the study of laboratory properties of rocks and soils, correlation of AE/MS activity with elastic and inelastic behavior, AE/MS behavior during deformation and dissolution of salt, coal breakage, laboratory scale hydraulic fracturing, and the application of AE/MS techniques to a number of mineral processing operations. Volume 1 and 2 cover both the basics and the applications of AE/MS techniques to geologic structures and materials. They provide the tools necessary for the newcomer as well as a great catalogue of applications for use by the more experienced engineer and researcher.