Interseismic Velocity Field and Seismic Moment Release in Northern Baja California, Mexico

Gonzalez-Ortega, J. A.; Gonzalez-Garcia, J. J.; Sandwell, David T.

doi:10.1785/0220170133

Cited by 9 publications

(8 citation statements)

References 40 publications

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“…The next level of agreement between the seismic and geodetic moment rates (with a ratio of ∼0.5) is found within the LSP and MVI seismic source zones. Near unity, ratios indicate that a large proportion of the accumulated strain has been released by earthquakes in these seismic source zones and thus having a low potential of having major damaging earthquakes in the near future (e.g., D'Agostino, 2014;Déprez et al, 2013;González-Ortega et al, 2018;Palano et al, 2017). This observation confirms the result of Mazzotti et al (2011) who found good agreement between the two moment rates in PUG (0.77) and MVI (0.83) ( Within the PUG and OLY seismic source zones, we observe moment excesses (≤−0.4 × 10 20 N m) resulting from a relatively large seismic moment rate.…”

Section: Potential Earthquake Hazardsmentioning

confidence: 99%

“…On one hand, agreement in the moment rate is found between the two data sets within measurement uncertainties (e.g., D'Agostino, 2014; Field et al., 1999; Kao et al., 2018; Mazzotti et al., 2011) while on the other hand, there is a disagreement between the two data sets with the geodetic moment rate typically higher than the seismic moment rate (e.g., Masson et al., 2004; Mazzotti et al., 2011; Palano et al., 2017; Ward, 1998a, 1998b). Based on the assumption of a constant rate of strain accumulation that is both elastic and inelastic and seismic moment release that is purely elastic, the degree of seismic and aseismic crustal deformation has been quantified and several factors have been invoked to explain the discrepancies between them (e.g., England & Molnar, 1997; González‐Ortega et al., 2018; Guest et al., 2006; Masson et al., 2004, 2006; Middleton et al., 2017; Palano et al., 2017; Walpersdorf et al., 2006). In the absence of aseismic deformation, areas, where the rate of geodetic strain accumulation exceeds the rate of seismic moment release, have been classified as having high potential for seismic hazard.…”

Section: Introductionmentioning

confidence: 99%

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Strain Accumulation and Release Rate in Canada: Implications for Long‐Term Crustal Deformation and Earthquake Hazards

et al. 2021

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To advance the understanding of crustal deformation and earthquake hazards in Canada, we analyze seismic and geodetic data sets and robustly estimate the crust strain accumulation and release rate by earthquakes. We find that less than 20% of the accumulated strain is released by earthquakes across the study area providing evidence for large‐scale aseismic deformation. We attribute this to glacial isostatic adjustment (GIA) in eastern Canada, where predictions from the GIA model account for most of the observed discrepancy between the seismic and the geodetic moment rates. In western Canada, only a small percentage (<20%) of the discrepancy can be attributed to GIA‐related deformation. We suspect that this may reflect the inaccuracy of the GIA model to account for heterogeneity in Earth structure or indicate that the present‐day effect of GIA in western Canada is limited due to the fast response of the upper mantle to the deglaciation of the Cordillera Ice Sheet. At locations of previously identified seismic source zones, we speculate that the unreleased strain is been stored cumulatively in the crust and will be released as earthquakes in the future. The Gutenberg‐Richter model predicts, however, that the recurrence interval can vary significantly in Canada, ranging from decades near plate boundary zones in the west to thousands of years in the stable continental interior. Our attempt to quantify the GIA‐induced deformation provides the necessary first step for the integration of geodetic strain rates in seismic hazard analysis in Canada.

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Section: Potential Earthquake Hazardsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Strain Accumulation and Release Rate in Canada: Implications for Long‐Term Crustal Deformation and Earthquake Hazards

et al. 2021

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“…A NE‐SW transect across northern Baja California crosses several NW‐SE oriented faults or fault zones that accommodate dextral plate motion at this latitude (Figure 1). At the eastern boundary of the plate margin, the Cerro Prieto Fault, which is the southern extension of the San Andreas and San Jacinto Faults, has a present day (from GPS) slip rate of ~40 mm/a (Bennett et al, 1996; González Ortega et al, 2018). The Laguna Salada Fault and faults within the Sierra El Mayor‐Sierra Cucapah (Axen et al, 1999; Axen & Fletcher, 1998; Fletcher et al, 2014; Fletcher & Spelz, 2009) are southern extensions of the Elsinore Fault (Suarez‐Vidal et al, 1991) and accommodate at least an additional ~2–3 mm/a (Mueller & Rockwell, 1995) immediately west of the Cerro Prieto Fault.…”

Section: Agua Blanca Fault Geologic Backgroundmentioning

confidence: 99%

Time‐Invariant Late Quaternary Slip Rates Along the Agua Blanca Fault, Northern Baja California, Mexico

et al. 2020

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Fault slip rates inform models of strain accumulation and release, which over geologic time may vary or remain constant depending on factors like structural complexity, fault strength, deformation rates, and proximity to other faults. In this study, we present a Late Pleistocene-Holocene slip history based on four new geologic slip rates for the Agua Blanca Fault (ABF), which transfers Pacific-North American dextral plate boundary motion across the Peninsular Ranges of northern Baja California. Time-averaged slip rates from three sites are 2.8 + 0.8/−0.6 mm/a since~65.1 ka, 3.0 + 1.4/−0.8 mm/a since~21.8 ka, 3.2 + 1.0/−0.6 mm/a since~12.5 ka, and 3.5 + 5.1/−2.0 mm/a since~1.4 ka; however, the actual slip rate may be closer to 4 mm/a when off-fault slip and age interpretation uncertainties are considered. Significantly, although the ABF has more in common in terms of length, net offset, and slip rate with known variable slip rate faults, the most straightforward age and offset interpretations for the ABF suggest constant slip rates over~10 kyr time scales. As with other constant slip rate faults, comparable neighboring faults that might modulate the ABF slip rate are absent, suggesting that fault interaction, or lack thereof, may be a more significant factor controlling fault behavior on this and potentially other faults. The new rates indicate that the ABF accommodates at least half of total slip across the Peninsular Ranges, clarifying strain partitioning for seismic forecasting models that previously lacked modern geologic slip rate constraints for this domain of the plate boundary.

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“…The Indiviso fault lies ∼10 km southwest of the Cerro Prieto fault which hosted M w ∼ 7, 6.1, and 5.4 earthquakes in 1934, 1980, and 2006, respectively (Suárez‐Vidal et al, ). Faulting in this region collectively accommodates ∼4–5 cm/year of NW‐SE right‐lateral shear at this latitude (González‐Ortega et al, ), but how this strain rate is distributed among individual structures is currently poorly understood.…”

Section: Overview Of the El Mayor‐cucapah Earthquakementioning

confidence: 99%

Extent of Low‐Angle Normal Slip in the 2010 El Mayor‐Cucapah (Mexico) Earthquake From Differential Lidar

et al. 2019

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We investigate the 4 April 2010 M w 7.2 El Mayor-Cucapah (Mexico) earthquake using three-dimensional surface deformation computed from preevent and postevent airborne lidar topography. By profiling the E-W, N-S, and vertical displacement fields at densely sampled (∼300 m) intervals along the multisegment rupture and computing fault offsets in each component, we map the slip vector along strike. Because the computed slip vectors must lie on the plane of the fault, whose local strike is known, we calculate how fault dip changes along the rupture. A principal goal is to resolve the discrepancy between field-based inferences of widespread low-angle (<30 ∘ ) oblique-normal slip beneath the Sierra Cucapah, and geodetic and/or seismological models which support steeper (50 ∘ -75 ∘ ) faulting in this area. Our results confirm that low-angle slip occurred along a short (∼2 km) stretch of the Paso Superior fault-where the three-dimensional rupture trace is also best fit by gently inclined planes-as well as along shorter (∼1 km) section of the Paso Inferior fault. We also characterize an ∼8-km fault crossing the Puerta accommodation zone as dipping ∼60 ∘ NE with slip of ∼2 m. These results indicate that within the northern Sierra Cucapah, deep-seated rupture of steep faults (resolved by coarse geodetic models) transfers at shallower depths onto low-angle structures. We also observe a statistically significant positive correlation between fault dip and slip, with slip pronounced along steep sections of fault and inhibited along low-angle sections. This highlights the important role of local structural fabric in controlling the surface expression of large earthquakes.

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Interseismic Velocity Field and Seismic Moment Release in Northern Baja California, Mexico

Cited by 9 publications

References 40 publications

Strain Accumulation and Release Rate in Canada: Implications for Long‐Term Crustal Deformation and Earthquake Hazards

Strain Accumulation and Release Rate in Canada: Implications for Long‐Term Crustal Deformation and Earthquake Hazards

Time‐Invariant Late Quaternary Slip Rates Along the Agua Blanca Fault, Northern Baja California, Mexico

Extent of Low‐Angle Normal Slip in the 2010 El Mayor‐Cucapah (Mexico) Earthquake From Differential Lidar

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