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<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:creator>Nicholas M. Beeler</dc:creator>
  <dc:date>2022</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;If brittle fault strength depends only on friction, slip instability is discouraged at low effective normal stress,&amp;nbsp;&lt;/span&gt;&lt;i&gt;σ&lt;/i&gt;&lt;span&gt;. Stress drop and the critical stiffness necessary for unstable sliding both vanish with&amp;nbsp;&lt;/span&gt;&lt;i&gt;σ&lt;/i&gt;&lt;span&gt;; small earthquakes cannot occur. Very low&amp;nbsp;&lt;/span&gt;&lt;i&gt;σ&lt;/i&gt;&lt;span&gt;&amp;nbsp;is inferred in the source region of low-frequency earthquakes (LFEs) on the San Andreas fault (SAF). Moreover, if pore pressure,&amp;nbsp;&lt;/span&gt;&lt;i&gt;p&lt;/i&gt;&lt;span&gt;, is undrained at low&amp;nbsp;&lt;/span&gt;&lt;i&gt;σ&lt;/i&gt;&lt;span&gt;, then instabilities are prevented at all scales. This is due to dilatant strengthening which arises due to a dependence of porosity on strain rate. Dilatant strengthening is&amp;nbsp;&lt;/span&gt;&lt;i&gt;σ&lt;/i&gt;&lt;span&gt;-independent and dominates at low&amp;nbsp;&lt;/span&gt;&lt;i&gt;σ&lt;/i&gt;&lt;span&gt;. Undrained&amp;nbsp;&lt;/span&gt;&lt;i&gt;p&lt;/i&gt;&lt;span&gt;&amp;nbsp;is inferred over time scales of less than a few days for the SAF LFEs. Based on experiments that measure rapid contact overgrowth between 350 and 530°C at very low&amp;nbsp;&lt;/span&gt;&lt;i&gt;σ&lt;/i&gt;&lt;span&gt;, fault failure controlled by time-dependent cementation is invoked as an explanation for the SAF LFEs. Because this “cohesion” is&amp;nbsp;&lt;/span&gt;&lt;i&gt;σ&lt;/i&gt;&lt;span&gt;-independent, stress drops can occur at&amp;nbsp;&lt;/span&gt;&lt;i&gt;σ&lt;/i&gt;&lt;span&gt;&amp;nbsp;=&amp;nbsp;0. If in addition cohesion exceeds any dilatant strengthening during slip, cohesion dominates strength at low&amp;nbsp;&lt;/span&gt;&lt;i&gt;σ&lt;/i&gt;&lt;span&gt;. Dilatancy measured in prior faulting and shear experiments indicate that at all stress levels steady-state porosity depends on&amp;nbsp;&lt;/span&gt;&lt;i&gt;σ&lt;/i&gt;&lt;span&gt;&amp;nbsp;in addition to strain rate. Moreover, porosity at low&amp;nbsp;&lt;/span&gt;&lt;i&gt;σ&lt;/i&gt;&lt;span&gt;&amp;nbsp;depends elastically on the confining and differential stresses. A model with these additional pore pressure effects, friction, and time-dependent cohesion, applied to the SAF LFEs produces stress drops, slip speeds, and durations that are consistent with the observations, when the shear-induced dilatancy is not extreme.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1029/2022JB024335</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>American Geophysical Union</dc:publisher>
  <dc:title>Brittle faulting at elevated temperature and vanishing effective stress</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>