"Previously installed instrumentation located underground and on the surface detected the rockburst and triangulated the position of the event close to the 186 working area"

+ Looks like they could do some triangulation.

------------------·
"A microseismic monitoring system at the Galena mine used an array of 43 geophones located throughout the mine that comprised two distinct sub-systems installed during different decades. A computer on the 4600 level controlled the wide area network (WAN), that consisted of 30 geophones and covered most of the active mine workings. A computer located on the 3700 level controlled the local area network (LAN), which monitored the 98 stope on the 4000 level and was made up of 13 geophones. These computers relayed information to the surface, through fiberoptic cables, where the data was processed. The processing computer located events by triangulation of information received from at least three geophones. The microseismic monitoring system was separate from a seismograph recording station located on the surface.

· Seismic event locations were not routinely plotted on mine maps, but the events were recorded, and posted daily on a bulletin board in tabular form showing magnitude, 3-D coordinates (easting, northing and elevation) and the stope or area affected (an occurrence located within a 350-foot radius). The accuracy of a specific event location was generally considered to be 50 feet or less, depending on the magnitude of the event and the number of geophones sensing it. Mine management indicated that information from the microseismic system had never predicted a rockburst at the Galena Mine"

-----------------------------
+ Event location accuracy was 50 feet or less. that's pretty tight.

* * * *

"· Wall rock in the 46-186E stope was steeply dipping, thinly bedded grayish-green quartzite and metamorphosed alternating beds of light and dark siltstone. Iron-stained quartzite and siltite dominated the northwest wall. Both the back and southeast wall were characterized by quartzite and siltite breccia (containing silver and copper minerals) cemented with quartz and carbonate. The 46-186E stope was observed to be intersected by various orientations of geologic planar features, resulting in a very blocky stope wall surface "
* * * *
Hmmm...Interesting.
* * * *
· Ground support was provided with Split Set stabilizers (staggered 4-foot and 6-foot lengths with 6-inch by 6-inch bearing plates and 12-inch by 16-inch by 7/8-inch plywood boards). Reportedly, the two victims were installing rock bolts with a jack leg drill near the turn in the stope (approximately 50 feet from the 186 raise) at the time of the rockburst.
* * * *
+ Did the miners have a hand in it ?

* * * *
Subsequent to the recovery effort, additional burst damage occurred in the hanging wall, and propagated 5 feet to 6 feet further toward the 186 raise. Several "thumps" and "pops" were audible as the investigation proceeded.
* * * *
+ Makes for a nervous investigation. The thumps and pops were probably in the 1000-12000 Hz audible range...maybe higher harmonics from infrasound (?).

====================
Anyway, the 4600 level (1.56 km?) and rockburst was located within 50 feet by the mine instrumentation. The CNSS located an earthquake at 2 km depth at the same time I believe. This appears to be a descrepancy since the mine system and the P-wave as measured by CNSS seem to locate two separate events...but were they ?

Maybe, as you say, the CNSS depth is incorrect and should match the mine system's depth. In which case, the CNSS system registered it as an earthquake (not a "rockburst"...though they may be feathers from the same animal perhaps).

Just my $.02 worth