Download or read book Paleoseismic Investigation of the San Gorgonio Pass Fault Zone Near Cabazon California written by Shahid Ramzan and published by . This book was released on 2012 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: The discontinuous nature of the San Andreas fault at San Gorgonio Pass has led to competing models about whether or not large earthquakes can rupture through this structurally complex region. To test these models the author excavated trenches across the San Gorgonio Pass fault zone (SGPFZ) near Cabazon as part of a larger effort. The trench site is located ~100 m to the east of a site excavated in 1997 by Yule where trenches uncovered evidence for at least one earthquake 500-700 yrs ago. At the 1997 site, extensive bioturbation and low sedimentation rates hampered efforts to distinguish events. The new site, located where two alluvial fans merge, was selected for its higher sedimentation rates and excellent stratigraphy. Evidence from Cabazon supports a model with infrequent ruptures (by San Andreas fault standards) in San Gorgonio Pass and rare through-going events.
Download or read book A 6000 year Record of Large Infrequent Earthquakes on the San Andreas Fault System in San Gorgonio Pass Near Cabezon California written by Lisa Wolff and published by . This book was released on 2019 with total page 97 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 15 km-wide compressive stepover made by the San Andreas Fault (SAF) system in the San Gorgonio Pass (SGP) region raises questions about the frequency and types of San Andreas earthquakes that happen in the SGP. The 1812 ~M7.5 Wrightwood rupture did not reach the SGP and supports a model whereby the structural complexity here inhibits rupture. However, the 2008 ShakeOut Scenario M7.8 SAF earthquake models a larger earthquake that breaks through the pass in a 300+ km rupture that extends from the Salton Sea to the northern Mojave. Paleoseismic records north and south of SGP indicate that the SAF breaks in large events that happen on average in ~100 and ~200 yr intervals, respectively. This study describes evidence for timing and recurrence for large earthquakes within the pass to test whether the SGP region inhibits or permits earthquakes like the ShakeOut Scenario event. My thesis report describes the findings of a 'mega' trench excavation (9 m deep, 45 m long, and 30 m wide) across the San Gorgonio Pass Fault Zone (SGPFZ) in summer 2013 near Cabazon, CA. The megatrench uncovered ~6000 yr-old sedimentary sections and two thrust zones with four total splays (zone 1 = F1-F3, and zone 2 = F4). Logging and retro-deformation of the trench walls them provides strong evidence for paleoseismic events 1, 2, 3, and 5, and weak evidence for event 4. We collected 138 charcoal samples from trench 8 and processed 54 samples using 14C Radiocarbon age dating protocols. Radiocarbon ages range from ~400 to ~5400 yrs BP (before present). Calibrated 14C ages constrain the timing of paleoseismic events using OxCal 4.3.4. The most recent event shows a modeled age of 633-750 yrs BP and the oldest event is >5300 yrs BP. This defines two recurrence intervals (Cab1-Cab2 and Cab2-Cab3) of ~450 years ~1800 yrs for the SGPFZ. It must be noted that conventional-sized trenches from 1997 found three thrust zones at the Cabazon site. The megatrench uncovered just two thrust zones, indicating that a third zone may remain uncovered to the south of the excavation. Fault orientations in the trench, plus the occurrence of bedrock in the footwall of F4, support this possibility. The paleoseismic data reported here are likely incomplete. The results of my study support a model where M7.8 ShakeOut type events happen 18 to 4 times less frequently than more common SAF events in areas to the north or south, respectively.
Download or read book Paleoseismic Investigation of the San Andreas Fault Zone in Portola Valley California written by Robert Harvey Wright and published by . This book was released on 2002 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paleoseismicity of the San Gorgonio Pass Fault Zone at Millard Canyon written by Paul McBurnett and published by . This book was released on 2011 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paleoseismic Investigations of the Northern San Andreas Fault at the Vedanta Site Marin County California written by Nelson Timothy Hall and published by . This book was released on 1994 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paleoseismic Investigations of the San Andreas Fault on the San Francisco Peninsula California Text and figures written by Nelson Timothy Hall and published by . This book was released on 1995 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paleoseismic Study of the Southern Sargent Fault Santa Clara and San Benito Counties California written by Jeffrey M. Nolan and published by . This book was released on 1995 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paleoseismic Investigations of the San Andreas Fault Old Canada Road Site San Mateo County California written by Robert H. Wright and published by . This book was released on 1999 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paleoseismic Investigation of the Serra Fault San Francisco Peninsula California written by James V. Hengesh and published by . This book was released on 1996 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The San Andreas Fault System in the Vicinity of the Central Transverse Ranges Province Southern California written by Jonathan C. Matti and published by . This book was released on 1992 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paleoseismic Investigation of the San Andreas Fault on the North Coast Segment Near Manchester California written by John N. Baldwin and published by . This book was released on 1996 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Effects of Dynamic Stress on Fault Interaction and Earthquake Triggering in the San Gorgonio Pass and San Jacinto CA Regions written by Jennifer Mary Tarnowski and published by . This book was released on 2017 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: We investigate how dynamic stresses can affect the occurrence of earthquakes in two regions in southern California. First we look at the San Gorgonio Pass (SGP) with 3D dynamic finite element models to investigate potential rupture paths of earthquakes propagating along faults in the western SGP. The SGP has several structurally complex regions because the San Andreas Fault splinters into many different fault strands and there are additional regional fault zones present in this location. It has long been suspected that this structural knot, which consists of the intersection of various non-planar strike-slip and thrust fault segments, may inhibit earthquake rupture propagation between the San Bernardino strand of the San Andreas Fault System and the San Gorgonio Pass Fault Zone. With simplified models, we find that nucleating on the San Bernardino strand does not produce through-going rupture, but that nucleation on the San Gorgonio Pass Fault Zone may produce through-going rupture in some scenarios. With more complex fault geometries, we find the stress and subsequent rupture propagation patterns are highly influence by the fault geometry and the initial stress field assumptions. Second, we look at the San Jacinto Fault Zone (SJFZ) for evidence of remote triggering. We find that, while rare, local events are triggered along the SJFZ by large magnitude remote events and that various methods are required to validate these examples of triggering.
Download or read book San Andreas Fault Zone in San Gorgonio Pass Southern California written by Clarence Roderic Allen and published by . This book was released on 1957 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paleoseismic Investigation of the San Andreas Fault Portola Valley California written by James Aaron Wetenkamp and published by . This book was released on 2008 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the Workshop on Paleoseismology 18 22 September 1994 Marshall California written by and published by . This book was released on 1994 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The San Andreas Fault Zone in San Gorgonio Pass California written by Clarence Roderic Allen and published by . This book was released on 1954 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paleoseismic Investigations of the San Bernardino Segment of the San Andreas Fault at Plunge Creek San Bernardino California written by Safaa Abdul Dergham and published by . This book was released on 2002 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:
