By Scott Briscoe

We are pleased to publish another guest blog this week! Scott Briscoe is a geologist who has worked in both exploration and mining roles in Nevada, California, Alaska and Western Australia.  He is a professional geologist currently doing exploration in Nevada.  His specialties include mapping, advanced geological modeling, leading teams, identifying and solving problems in the pursuit of finding ore. You can read more of his articles on his own blog Briscoe Geology. Below is the process Scott went through to visualize his earthquake data, using Leapfrog Geo.

 

In late September, the area near Mammoth Lakes, California began having a resurgence in earthquake activity. Seeing as how there has been a good deal of volcanism there in recent millenia I wanted to visualize the earthquake activity in 3D. I decided to model this in Leapfrog Geo by ARANZ Geo Limited. A few minutes is all it took to bring the earthquake data from here into Leapfrog. I did a search by area with all magnitudes for the date range 8-1-2014 through 10-14-2014.

It looks interesting in map view, but I really became curious what the mechanisms going on below
surface were.

From there I made all of the depths in kilometers negative and converted the date format to one usable in Leapfrog then imported the csv as location data. In order to make the scale look reasonable I applied a Z-axis scale correction factor of 0.05 times the X and Y axes. Now I had my earthquake data in 3D. I colored by date and sized the 3D dots by earthquake magnitude. I then created some planes from a structural trend to   visualize the depth in kilometers.

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Immediately obvious is that the bulk of these earthquake swarms are linear or tubular shaped features with the rest residing in somewhat planar features likely representing faults.

What also became clear after making a series of animations by filtering the dates is that each swarm was getting shallower as time passed.

Of note is the fact that there are three distinct swarms.  A large central swarm about 2.5 km north of the airport, a small swarm  underneath the Mammoth Skate Park and a new swarm 1 KM northwest of
Mount Huntington.

Since August 1st, 2014 there have been 922 earthquakes above magnitude one of which 10 have been above magnitude 3.

I am not a volcanologist, and am merely bringing my limited understanding from my career in geology to attempt to understand these events. The information I could find from the USGS and CalVo brought up more questions than they answered. To me, from reading various volcanologist blogs this looks to be dike emplacement events.

I imagine if the bulk of the quake swarms move to be shallower than 4KM, there will be a heightened warning from the California Volcano Observatory based on what I’ve read from other volcanoes from around the world.

Please see the animation I created below: