Wednesday
Jul272016

Electromagnetic survey for mapping near-surface chlorides

The EM-31 is an excellent tool when the depth of interest < 6 meters.  Here it is coupled with a DGPS receiver to provide very rapid mapping even when on foot. 

This survey mapped near-surface chlorides (high electrical conductivity) and deep utility corridors that serve as possible migration pathways.

Good conditioning prior to our Wales Coastal Path hike.

Wednesday
Jul272016

Looking back from one extreme to another

With this heat wave, it helps to look back at cooler time.  This was taken during a refraction survey to support a seismic site classification from Vp / Vs.  Single digits and windy.  At least when its cold you can layer up and get warm.  Doesn't work in reverse when it is hot; there are practical limits to layering down.

Friday
Jun242016

The vertical fingerprint of earthquake cycle loading in southern California

Howell et al find a coherent pattern of uplift and subsidence straddling the San Andreas fault system in southern California using vertical velocities derived from global positioning system data, improving the quantification of seismic hazards in southern California and beyond.

http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2741.html

Monday
Jul202015

Earthquake-Induced Ground Motion

Attended an excellent workshop in earthquake seismology for engineering applications. Offered by ASCE and presented by Dr. Praveen Malhotra, PE.  All continuing education should be this caliber!

 

Thursday
Jun252015

Injection induced seismicty

Very interesting collection of papers in The Leading Edge regarding injection-induced seismicity.  Fluid injection during petroleum production can cause crustal movement with significant seismic energy. 

"Preliminary hazard models indicate that areas experiencing the highest rate of earthquakes in 2014 have a short-term (one-year) hazard comparable to or higher than the hazard in the source region of tectonic earthquakes in the New Madrid and Charleston seismic zones."