{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"44031092e8e8e382bef76bb9874d70715aea2aa50b8db58cbd5a69d5ea366626","created":"2026-10-03T07:18:02Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"9d672a8edc5a4a637ac41a648b49e671e60934052e587e4df3698bf4fdbbafe7","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"earth.earthquake-physics.heat-flow-paradox","kind":"phenomenon","literature_status":"partially-resolved","n":"1","parents":[],"plain":"Rock friction measured in the lab predicts that a sliding fault like the San Andreas should heat the ground around it. No such heat is seen, so the fault must be weaker than lab rocks.","posed_since":"1969","precise":"The absence of a frictional heat-flow anomaly over the San Andreas fault implies mean shear stress below about $2e8\\,\\mathrm{dyn}/\\mathrm{cm}^{2}$, while Byerlee friction (coefficient 0.6 to 0.85) at seismogenic depth predicts about $1e9\\,\\mathrm{dyn}/\\mathrm{cm}^{2}$. Determine whether mature faults are statically weak (weak clay minerals, high pore pressure) or only dynamically weak during slip. An answer is a measured in situ shear stress and friction profile consistent with heat flow and stress orientation data. The residual question concerns locked, seismogenic fault segments.","problem_ref":null,"references":"","settled_by":"Deep borehole stress, pore-pressure and temperature measurements on mature faults combined with friction tests on recovered fault rock.","status_note":"SAFOD core showed the creeping San Andreas segment is statically weak through saponite-bearing gouge with friction coefficient below about 0.15 (Lockner and coauthors, Nature 2011, https://doi.org/10.1038/nature09927); whether locked seismogenic segments are statically or only dynamically weak remains open.","title":"Why do mature faults slip at low stress without measurable heating?","topic_ref":"1dbf2e518640764e9008c15991558e9c0810fdb6b00292d36b150438ae8a1784"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"5e6fca620806a66a8dd548a606382dfcdb3cafffcedb0a2a32209d80e7cf600b","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"218560c014b3a374a54dc9c6c531c5455ea941bc5d608ca6c0c887072eaee3e5","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"vWDGknDdW2HCR5sVtVlhihcvS9UU8Bw2kVACSP55ZmVq3P07iugxZd53Eq6xALWNRa92fX99Ps5sv2AHtG6tAQ"},"schema":"pubphys.envelope/1"},"record_hash":"5e6fca620806a66a8dd548a606382dfcdb3cafffcedb0a2a32209d80e7cf600b","leaf_index":1311}