Anomalies of geomagnetic variations in the southwestern united states

Abstract

A survey with temporary geomagnetic field stations (Askania Variographs) has been conducted in the southwestern United States in order to study local differences of geomagnetic variations. Anomalous large Z-variations, accompanied with a slight reduction of the variations in D and H, have been recorded along the California coastline for long-period (Sq) and short-period (bays, ssc's) variations. This Californian coastal anomaly has been interpreted as edge-effect of the Pacific Ocean and its effect upon the induction within the highly conductive substratum in the upper mantle, thereby allowing conclusions about the deep conductivity structure Less pronounced anomalous variations further inland in central California (Sierra anomaly) seem to be caused by conductivity differences in the continental surface layers. A third anomaly between Tuscon, Arizona, and Sweetwater, Texas (Texas anomaly), has been interpreted as a change in the deep conductivity structure which occurs along the eastern margin of the Rocky Mountains. © 1964, Society of Geomagnetism and Earth, Planetary and Space Sciences. All rights reserved.