Open AccessHeat flow through the San Jacinto fault zone, southern California
Author(s) -
Lee TienChang
Publication year - 1983
Publication title -
geophysical journal of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0016-8009
DOI - 10.1111/j.1365-246x.1983.tb02829.x
Subject(s) - geology , fault (geology) , seismology , heat flow , san andreas fault , anomaly (physics) , shear (geology) , shear stress , petrology , thermodynamics , thermal , physics , condensed matter physics
Summary Five new and three existing heat flow measurements ranging from 0.027 to 0.078 W m ‐2 indicate that heat flow increases toward the San Jacinto fault, a major branch of the San Andreas fault in southern California. Determined somewhat subjectively, this heat‐flow distribution has a half‐width of 14 km and a maximum of 0.032 W m ‐2 above a regional value of 0.042W m ‐2 . The heat flow anomaly reported here is believed to have resulted from conductive dissipation of heat generated during faulting, though hydrothermal discharge occurs at several distant locations along the fault. Assuming an average slip rate of 2.5 cm yr ‐1 and depending on the model used, the needed long‐term mean dynamic shear stress for the anomaly may range from 28 to 63 MPa with a favoured choice from 30 to 40 MPa. Compared to the San Andreas fault in the Coast Ranges of central California where appears a flat 100 km wide regional anomaly of 0.033 W m ‐2 , the shear heating rate along the San Jacinto fault (0.046 MW km ‐1 ) is about one‐seventh of that along the San Andreas fault; however, the absence of a peak anomaly over the San Andreas fault trace requires a shear stress of 10 MPa only.