Proceedings of the 12th International INQUA meeting on paleoseismology, active tectonic and archaeoseismology

C O N C L U S I O N S The Puente Hills provide an excellent sandbox upon which to model tectonic uplift rates based on patterns of fluvial geomorphic deformation. The ~3.0 mm/yr slip rate of the Whittier fault is the temporal chronometer upon which the deformation models are calibrated. The uplift rate is then determined by two independent methods; drainage basin development and terrace uplift. Both methods yield similar temporally-increasing uplift rates. Emergent ~1Ma, thePuenteHills fluvial systemwas fullydeveloped by 600 ka. The Puente Hills uplift is shown to have progressively increased through time, as reflected in both analyses. The initial uplift rate of 0.3 mm/year, increases to 0.7 mm/year by ~200 ka, and increases again to 1.2 mm/yr by 20 ka. The 6 mm/yr northward movement of the Santa Ana Mountains indenter is interpreted as the force driving this late Quaternary acceleration of the Puente Hills uplift in Santa Ana River canyon. Acknowledgements: The work summarized in this paper spans decades and includes dozens of people along the way. Beginning in 1992 with the paleoseismic trenching of the Whittier fault (Gath, Gonzalez & Rockwell, 1992) and the geomorphic strip mapping of the fault (Gath, 1997), to the OSL dating (Grant, Gath & Owen, 2006). The work was supported by USGS NEHRP grants in 1992 & 1997, and SCEC andUSGS grants in 2005&2006. Reviews by Tania Gonzalez significantly improved the paper. A C K N O W L E D G E M E N T S The work summarized in this paper spans decades and includes dozens of people along the way. Beginning in 1992 with the paleoseismic trenching of the Whittier fault (Gath, Gonzalez & Rockwell, 1992) and the geomorphic strip mapping of the fault (Gath, 1997), to the OSL dating (Grant, Gath & Owen, 2006). The work was supported by USGS NEHRP grants in 1992 & 1997, and SCEC and USGS grants in 2005 & 2006. Reviews by Tania Gonzalez significantly improved the paper. Fig. 8: Correlation of Puente Hills terraces (Fig. 7) using 1 Ma Santa Ana River deflection for emergence age of Qt7, 600 ka for development of the three primary drainages (Qt6), correlated pedogenic ages of 120 ka and 210 ka for Qt 3 & Qt4, OSL ages for Qt1 & Qt2, and the 20 ka sea level low for the Santa Ana River thalweg.