{"record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"3977f34e90b5e5555b09a8218d23109aca2e42c4b4f701e420812ab8c687f889","created":"2026-10-03T07:18:02Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["5475cf5dc5b1a72283d26dc95dc6e00d7ea4e00096a7c6492e409a1816eeb011"],"salt":"23d0830e4f226d5bdeaa350648a0286b9c1d60c5a58c56cd25f27f3835cb49e8","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"yes-no","assisted_by":[],"external_id":"earth.earthquake-physics.nucleation-phase","kind":"well-posed","literature_status":"contested","n":"1","parents":[],"plain":"Lab experiments show faults creep slowly before they snap, but it is unclear whether real large earthquakes do this in a way instruments can see. Some big quakes had small earthquakes or slow slip before them, others did not.","posed_since":"","precise":"Rate-and-state friction predicts a quasi-static nucleation zone of size $L_c \\sim G D_c/(\\sigma (b - a))$ before dynamic rupture. Determine whether earthquakes with $M \\ge 7$ are systematically preceded by aseismic slip or foreshock sequences distinguishable from ETAS background clustering (ETAS: a statistical model in which every earthquake can trigger later ones) at amplitudes above present geodetic and seismic detection thresholds. An answer is a statistically significant catalog-wide test.","problem_ref":null,"references":"","settled_by":"A global test on dense geodetic and template-matched seismic catalogs comparing precursory activity before large events against ETAS-simulated catalogs.","status_note":"Precursory slow slip was reported before the 2011 Tohoku and 2014 Iquique earthquakes; whether precursors are systematic remains disputed as of 2025.","title":"Do large earthquakes have a detectable preparation phase?","topic_ref":"1dbf2e518640764e9008c15991558e9c0810fdb6b00292d36b150438ae8a1784"},"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"739740f66d0b461437dcfdffa381ecb55a9df0a65865b6c69f6ebd263bb91b73","schema":"pubphys.attested/1"},"envelope":{"attested_hash":"9f4b70e31b98d9ec7aa52b850746afc1e69332ca2ca9a7751e41aba486821983","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"bVWzgnLqSZXJlf7rGU67TBSckep7v0dqrLCDp2V9FmITDx3IgNXZhygvyEOoZe-xUeXhykEf2d2-eTmtmRGrBA"},"schema":"pubphys.envelope/1"},"record_hash":"739740f66d0b461437dcfdffa381ecb55a9df0a65865b6c69f6ebd263bb91b73","leaf_index":1312}