EARTHQUAKES OF MEXICO


Figure 17. (s-p) travel time plot of UKSE.


M. Stephen Pierce (pierce@ectisp.net) is a consulting geolo- gist with over 35 years of exploration experience worldwide. While working with Superior Oil Co. and exploring for oil in Israel in 1980, Mr. Pierce wrote a basin analysis for the state of Israel at the government’s request. He explored Israel for Zion Oil & Gas from 2006 to 2012. He presented a paper on the Petroleum Potential of the Dominican Rp. to the 19th Geologic Congress in Santo Domingo, Dominican Rp. Mr. Pierce briefly taught geology at Navarro College, Corsicana, Texas. He holds a BS degree in geology from Long Beach State University and a Master’s in geology from San Diego State University.


Figure 18. Fourier plot suggests peak frequency 0.583 Htz of UKSE.


TUNGSTEN


Jim Burnell, CPG-11609 dialjeemincolo@aol.com


Final Thoughts


They say, “you can’t teach an old dog new tricks.” But in some cases I heartily disagree. From my EQ-1 seismometer records of earthquakes in Mexico, I have observed seismic evidence related to the transform faults of the Rivera Micro- plate and San Andreas Fault, active teconics in the Rio Grand Rift, and the East Pacific Rise Baja Spreading center. And I also recorded a bit of “flat slab subduction.”


I would recommend to any geologist who would like to gain experience and knowledge of the relation of earthquakes and tectonics to either build or invest in a small seismometer. There are always surprises.


References


Basic Exploration Geophysics, 1983, Exploration Fundamentals/100, Plato of Control Data Publications.


Bullard, F., 1984, Volcanoes of the Earth, University of Texas Press, Austin.


Cox, A., Hart, R., 1986, Plate Tectonics How it Works, Blackwell Scientific Publications, Inc.


DeMets. C., Traylen, 2000, Motion of Rivera Plate since 10 MA relative to the Pacific and North American plates and the mantle, Tectonophysics.


Fowler, C., 1990, The Solid Earth, Cambridge University Press.


IRIS, Explorations in Earth Science, Webpage, Iris Consortium.


Pardo M., Suarez, G., 1995, Shape of the subducted Rivera and Cocos plates in southern Mexico: Seismic and tectonic implications, Journal of Geophysical Research.


Regional Seismograms, Institute for Geophysics, University of Texas.


Tectonics Observatory, The unusual case of the Mexican sub- duction zone, California Institute of Technology, Tectonics Observatory website.


USGS Earthquake Hazards Program Website.  


Tungsten is a metal whose importance in our modern economy continues to rise. The symbol for tungsten - W - origi- nates from the Swedish name for the metal wolfram, seen in the mineral wolframite, one of the ore minerals of tungsten.


Tungsten’s properties make it indispensable in industry. Tungsten possesses the highest melting point of any metal (3422o C) and a density as high as gold (19.3 g/cm3). Tungsten retains its mechanical properties at high temperatures and has the lowest coefficient of expansion of all metals. In the form of tungsten carbide (WC), it is 6 times stiffer than steel with a hardness near that of diamond. Tungsten is extremely corrosion resistant.


Half of the world’s tungsten is used in the form of tungsten carbide. End uses include drills and cutting tools, electrodes, touch-screens, cemented carbides for powder, metallurgy, machine wear parts, mining and construction, deep drilling, fossil and nuclear power production, satellites, superalloys, and heavy metal alloys. In short, modern industry cannot function without tungsten.


Tungsten is near the top of a list developed by the British Geological Survey of mineral commodities, of minerals that are in danger of supply interruption. As if to emphasize the listing, China has begun to impose export quotas on the metal.


Tungsten is not currently mined in the U.S. China produces 80% of the world output. Only five mines operate outside China and Russia. China has moved from a net exporter of tungsten to an importer in just the last five years. The U.S. does produce some of our own tungsten from scrap, which makes up 30% of supply worldwide.


The pricing of tungsten is complex, as it is marketed in several forms. Ammonium paratungstate (known as APT) is a white crystalline powder of high purity; ferrotungsten is a master alloy of 75 to 85% tungsten used for steel alloys;


WO3 is marketed as a fine white powder. The price of WO3 has ranged from $8.63 to $20.50/pound from 2008 to 2013. The price was at that high point in June 2013. Roskill, the international metals broker, has predicted a growth of 6% per year in tungsten usage.


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