Following the 2003 Johannesburg, the 2007 Lisbon, and the 2011 Beijing workshops, we plan to organize the following activities associated with 2015 Montreal Congress of the International Society for Rock Mechanics (ISRM) on Underground Research Laboratory (URL) related studies. The activities include (1) and (2) on May 7, 2015 for a field visit from 7 am to 3 pm to Sudbury Neutrino Observatory (SNO) Lab and an afterward meeting on URL infrastructure at Sudbury, Canada; (3) on May 8, 2015 Friday 1 pm to 5 pm for a site visit to the Centre of Excellence in Mining Innovation, Laurenthian University; (4) on May 10, 2015, Sunday for the 4^th International URL Workshop at Montreal, Canada; and (5) during May 11-13, 2015 in an URL and underground study session, to be organized by the ISRM Congress.

As in previous URL workshops, we will discuss rock mechanics and geoscience advances associated with excavation damage zone characterization and couple process testing for radioactive waste assessment, recent large excavations in deep physics facilities with interests for multi-disciplinary studies, and controlling processes in enhancing earth resource engineering. These topics are also the scope of the ISRM Commission on URL Networking. Similarity and differences among URLs will be discussed in the 4^th International URL Workshop.

Please contact jswang@lbl.gov for early logistics and questions for activities associated with the 4^th International URL Workshop. Please forward this announcement to your colleagues and encourage participation and contributions. I will be glad to contact whoever you recommend for these activities on your behalf and encourage lectures given in the workshop. We also plan to have a meeting for the ISRM Commission on URL Networking during the 4^th International Workshop to discuss future URL-related activities.