{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"c051c7a09aaf56a1f8e9c68354764f35543343f4afba2961a4fa0a1a9f136ccb","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5e6fca620806a66a8dd548a606382dfcdb3cafffcedb0a2a32209d80e7cf600b","ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b"],"salt":"096ede9b368006cc8afdfa2545a95f8637ec111ae9f11d2017076700476bf903","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":"2","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 $2 \\times 10^{8}\\,\\mathrm{dyn}/\\mathrm{cm}^{2}$, while Byerlee friction (coefficient 0.6 to 0.85) at seismogenic depth predicts about $10^{9}\\,\\mathrm{dyn}/\\mathrm{cm}^{2}$. 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":"5e6fca620806a66a8dd548a606382dfcdb3cafffcedb0a2a32209d80e7cf600b","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":null},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"c2cc215d810b7a5b03e62e4349869fb5072e74ac085d7b28fb51aa63162927f6","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"8957af04d39ebbcf81a6c137aa92e97e49fe03a05292c60bb30cca57f5ec8092","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"bvQPKTgVKeKHKVFvOnqU8VkytmIvgU0ZqlnCLOrYh5PnTOiCGoHAqtPdaBKIOgT98KLCyvgvWNvWTxwUnPdpAw"},"schema":"pubphys.envelope/1"},"record_hash":"c2cc215d810b7a5b03e62e4349869fb5072e74ac085d7b28fb51aa63162927f6","leaf_index":3190}