Thomas K. Rockwell

Thomas K. Rockwell
San Diego State University | SDSU · Department of Geological Sciences

Ph.D.

About

345
Publications
90,111
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
8,719
Citations
Additional affiliations
January 1983 - present
San Diego State University
Position
  • Professor (Full)

Publications

Publications (345)
Article
We studied the southern part of the NW-SE trending Sudetic Marginal fault (SMF), situated at the northeastern limit of the Bohemian Massif in central Europe, to assess its Quaternary activity. Eighteen trenches and thirty-four electric resistivity profiles were performed at Bílá Voda to study the fault zone and 3-dimensional distribution of a behea...
Article
Slip rates determined along the Elsinore and San Jacinto faults indicate that south of 33.5° N, the slip rate along the Elsinore fault decreases by ∼2.5 mm/yr, whereas the slip rate along the San Jacinto fault increases by nearly 6 mm/yr. A transfer of slip from the Elsinore to the San Jacinto faults is the likely explanation, but a fault with Holo...
Article
To constrain the timing of the past seven lake highstands in the Salton Trough, we compiled 423 radiocarbon dates, of which 284 are reliable and have good stratigraphic control, from paleoseismic and archeological sites in the basin. We developed two OxCal models that assume most charcoal, wood, seeds, and twigs recovered from organic mats at or ne...
Article
In the tectonically complex Imperial Valley, California (USA), the Imperial fault (IF) is often considered to be the primary fault at the U.S.-Mexico border; however, its strain partitioning and interactions with other faults are not well understood. Despite inferred evidence of other major faults (e.g., seismicity), it is difficult to obtain a hol...
Article
Full-text available
Pulverisation of rocks occurs through dynamic processes associated with earthquake ruptures. At the well-known pulverised rock outcrops along the San Andreas Fault (SAF), the intensity of pulverisation was shown to be highly heterogeneous on the outcrop (m-10s of m) scale, although detailed documentation of this heterogeneity is still lacking. Here...
Article
The quantification of rates for the competing forces of tectonic uplift and erosion has important implications for understanding topographic evolution. Here, we quantify the complex interplay between tectonic uplift, topographic development, and erosion recorded in the hanging walls of several active reverse faults in the Ventura basin, southern Ca...
Article
Stratigraphic evidence for coseismic subsidence has been documented in active-margin estuaries throughout the world. Most of these studies have been conducted in subduction zone or strike-slip settings; however, the stratigraphic response to coseismic subsidence in other tectonic settings would benefit from further study. Here we show evidence of l...
Article
Full-text available
Large, multi-fault earthquakes increase the threat of strong ground shaking and reshape the probability of future events across a system of faults. Fault junctions act as conditional barriers, or earthquake gates, that stop most earthquakes but permit junction-spanning events when stress conditions are favorable. Constraining the physical condition...
Article
Full-text available
Identifying the offshore thrust faults of the Western Transverse Ranges that could produce large earthquakes and seafloor uplift is essential to assess potential geohazards for the region. The Western Transverse Ranges in southern California are an E-W trending fold-and-thrust system that extends offshore west of Ventura. Using a high-resolution se...
Article
Full-text available
Keywords: coseismic scarps surface rupture paleoseismic trenching fault mechanics recurrence interval earthquake magnitude We present the results of detailed mapping and paleoseismic investigations along a section of the complex fault scarp array associated with the Cañada David detachment, a low-angle oblique normal fault that controls the southwe...
Article
Full-text available
In Southern California, plate boundary motion between the North American and Pacific plates is distributed across several sub-parallel fault systems. The offshore faults of the California Continental Borderland (CCB) are thought to accommodate ∼10–15% of the total plate boundary motion, but the exact distribution of slip and the mechanics of slip p...
Article
Important fault zone processes can be discerned from the characterization of fracture damage and chemical transformations associated with active seismic sources. To characterize the 2010 M7.2 El Mayor-Cucapah rupture zone, continuous samples of fault core and 23 samples of damaged rock were collected perpendicular to strike of the Borrego fault. Sa...
Chapter
Tectonic geomorphology of mountain fronts is that part of geomorphology concerned with processes and landforms near the junction of a piedmont and mountain front. Mountain fronts are generally segmented, and individual segments are evident from Google Earth imagery, processed LIDAR hillshades, aerial photographs from unmanned aerial vehicles (UAVs)...
Chapter
Coastal landforms at much higher elevations than the current sea level have long been recognized, and inferred to be evidence for past sea-levels and uplift. Despite this clear observation and correct association, the mechanisms that explained the relative sea-level change frequently were not fully understood. Marine terraces and coral reef tracts...
Article
Along tectonically active margins, the difference in elevations between global sea levels during highstands and uplifted marine terraces is a function of both tectonics and glacial-isostatic adjustment (GIA). However, disentangling the relative influence of these two processes remains a challenge for those trying to gain insights into either proces...
Article
We present results from complementary geological, topographic, seismic and electrical resistivity surveys at the Sagebrush Flat (SGB) site along the Clark fault (CF) strand of the San Jacinto fault zone trifurcation area southeast of Anza, California. Joint interpretation of these data sets, each with unique spatiotemporal sensitivities, allow us t...
Article
Full-text available
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 Ag...
Article
Full-text available
To investigate the subsurface geometry of a recently discovered, seismically active fault in the Ventura basin, southern California, USA, we present a series of cross sections and a new three‐dimensional fault model across the Southern San Cayetano fault (SSCF) based on integration of surface data with petroleum industry well log data. Additionally...
Article
The NNE–SSW-striking Yangsan Fault in southeastern Korea has been regarded as one of the most prominent seismogenic structures in the Korean Peninsula on the basis of instrumental and historical seismicity, and paleoseismic records along the fault zone. Its seismic behavior is, however, still uncertain due to long recurrence intervals of strong ear...
Conference Paper
The Pajarito fault system (PFS) is a low slip rate (~0.1 mm/yr), 50-km-long seismogenic fault system that bounds the western margin of the Rio Grande Rift. The PFS crosses the edge of Los Alamos National Laboratory (LANL) in Los Alamos, NM and is the largest contributing seismic source to LANL. Thus, understanding its paleoseismic record is key to...
Conference Paper
The Pajarito fault system (PFS) is a 50-km-long seismogenic fault system forming the active western margin of the Rio Grande rift in the vicinity of Los Alamos in north-central New Mexico. The PFS has a complex expression and includes four distinct faults: the main Pajarito (PF), Rendija Canyon (RCF), Guaje Mountain (GMF) and Sawyer Canyon (SCF) fa...
Article
The moment magnitude 7.2 El Mayor−Cucapah (EMC) earthquake of 2010 in northern Baja California, Mexico produced a cascading rupture that propagated through a geometrically diverse network of intersecting faults. These faults have been exhumed from depths of 6−10 km since the late Miocene based on low-temperature thermochronology, synkinematic alter...
Article
The current interseismic period for an event on the Coachella Valley segment of the San Andreas Fault (SAF) is ~300 years, much greater than the best-estimated average recurrence interval of ~180 years, prompting questions regarding earthquake recurrence and fault behavior. Digital Surface Models (DSMs) generated using Structure-from-Motion-Multivi...
Article
Complex fracture damage around large faults is often simplified to fit exponential or power law decay in fracture density with distance from the fault. Noise in these datasets is attributed to large subsidiary faults or random natural variation. Through a field study of the Borrego Fault (Baja California) damage zone, combining mm-resolution struct...
Article
Full-text available
We developed a forward model using the Trishear module in MOVE to better understand the structure of the northwestern San Fernando Valley and the relationship among the Santa Susana, Hospital, Mission Hills and Northridge Hills faults. This study was motivated by the 1971 San Fernando earthquake and previous work that inferred a high slip rate on t...
Conference Paper
The Pajarito fault system (PFS) is modeled as a late Quaternary, 50-km-long seismogenic fault system that bounds the western margin of the Rio Grande Rift; more importantly it crosses the edge of Los Alamos National Laboratory (LANL) in Los Alamos, NM. The PFS is the largest contributing seismic source to LANL, and thus, understanding its paleoseis...
Article
Full-text available
Active fold-and-thrust belts can potentially accommodate large-magnitude earthquakes, so understanding the structure in such regions has both societal and scientific importance. Recent studies have provided evidence for large earthquakes in the Western Transverse Ranges of California, USA. However, the diverse set of conflicting structural models f...
Article
Full-text available
Many fault zones trend through developed urban areas where their geomorphic expression is unclear, making it difficult to study fault zone details and assess seismic hazard. One example is the Holocene‐active Rose Canyon fault zone, a strike‐slip fault with potential to produce a M6.9 earthquake, which traverses the city of San Diego, California (U...
Article
Full-text available
In the desert of southeastern California, the geological and archaeological remnants of a once massive lake, Lake Cahuilla, are still visible. One of the most distinctive features marking Lake Cahuilla's relic shorelines is a series of rock fish trap features that, in some cases, stretch across thousands of square meters. These fish traps are sever...
Article
Full-text available
Observations of shallow fault creep reveal increasingly complex time‐dependent slip histories that include quasi‐steady creep and triggered as well as spontaneous accelerated slip events. Here we report a recent slow slip event on the southern San Andreas fault triggered by the 2017 Mw8.2 Chiapas (Mexico) earthquake that occurred 3,000 km away. Geo...
Conference Paper
The San Jacinto fault zone is one of the most seismically active structures in southern California and has produced 10 historical M>6 earthquakes. The San Jacinto fault zone comprises several fault strands, including (from N to S) the Claremont, Casa Loma, Clark, Coyote Creek, Superstition Mountain, and Superstition Hills faults. The Casa Loma faul...
Article
Full-text available
In this paper we investigate the dynamic behavior of a system of interconnected faults in the Brawley Seismic Zone (BSZ) in southern California. The system of faults includes the southern San Andreas Fault (SSAF), the Imperial Fault (IF), and a set of cross faults in the BSZ that may serve as connecting structures between the two larger faults. Geo...
Article
Lying between the Elsinore and San Jacinto faults, ~0.5 km SE of Roundtop, is a tonalitic corestone perched precariously on an exhumed corestone base. Such features are referred to as precariously balanced rocks (PBRs). Cosmogenic ¹⁰Be data listed in an online abstract suggest a tentative exhumation age of the PBR near Roundtop at ~35,000 years ago...
Article
We present surface evidence and displacement rates for a young, active, low-angle (∼20°) reverse thrust fault in close proximity to major population centers in southern California (USA), the Southern San Cayetano fault (SSCF). Active faulting along the northern flank of the Santa Clara River Valley displaces young landforms, such as late Quaternary...
Conference Paper
Full-text available
NASA/ADS Estimation of horizontal displacement by 3D-trench investigation on the northern part of the Yangsan fault at Dangu-ri, Gyeongju, SE Korea Show affiliations Jeong, S. H.; Naik, S.; Rockwell, T. K.; Kim, Y. S. We performed 3D trench to estimate horizontal displacement and further potential earthquake magnitude along the Yangsan fault, which...
Article
The past two southernmost San Andreas fault (SAF) ruptures occurred when ancient Lake Cahuilla was full, based on faulted lake sediment relationships and extensive liquefaction at sites near the shoreline. The times of the past two southern SAF ruptures have been reevaluated with new radiocarbon data on in situ stumps that grew between the past thr...
Conference Paper
Full-text available
SW Iberia region is the closest onshore area to the complex setting of the Southwest Iberian Margin and Gulf of Cadiz, a part of the Eurasia-Nubia plate boundary. Here, a sequence of late Pleistocene marine terraces is present allowing to estimate an uplift rate of circa 0.11 mm/yr, higher than for neighboring regions. However, the long-term uplift...
Conference Paper
Full-text available
The Aljezur Fault corresponds to the central section of the São Teotónio–Aljezur-Sinceira fault system (STASFS), located in southwest Portugal, Iberia. This fault system corresponds to a transpressive structure, mainly left-lateral with a minor reverse component that deforms a large regional abrasion surface of Plio-Pleistocene age. Several small t...
Conference Paper
Full-text available
The Eastern Betics Shear Zone (EBSZ), in SE Iberia, is a slow deformation zone with low seismicity. Given the lack of moderate-large earthquakes in historical times along the Carboneras fault (CF), palaeoseismological analyses are needed to better assess the seismic hazard of the area. The last paleoseismic and geological onshore-offshore studies o...
Article
To better understand the processes that control sub-grain fracturing in fault damage zones, we studied micro-scale damage in sandstones adjacent to the San Jacinto fault (SJF) where it is exhumed from a total depth of ∼220 m beneath a northeast-verging thrust that comprises part of a relic and dismembered flower structure. The thrust places high gr...
Article
Offset alluvial fans along the Elsinore fault in the south-central Coyote Mountains were studied to resolve an average late Quaternary slip rate for this major western strand of the San Andreas fault system in southern California. Alluvial fans and their offsets were mapped using high-resolution DEMs combined with field observations of fan-surface...
Article
A series of large storms attributed to Atmospheric River conditions struck the California coast in the winter of 1861–2. Although historical accounts document inland flooding, little is known about how the 1861–2 storms impacted the now heavily-developed California coast. Here we show that the 1861–2 storms emplaced a deposit of beach sand up to 50...
Article
South Portugal is characterized by low tectonic rates (<0.3 mm/a), with infrequent large seismicity. Recent studies indicate a coastal region in southwest Portugal uplifting at higher rates (0.11 ± 0.01 mm/a) than the remaining southern portion of Portugal (~0.04 mm/a); however, the mechanisms that drive this uplift are poorly understood. With the...
Article
To better understand the relationship between geomorphology and fault slip, we investigated the origins of topographic depressions previously interpreted as beheaded channels representing small offsets at Van Matre Ranch (VMR) along the San Andreas fault, Carrizo Plain, California. We excavated four fault-parallel trenches (T1–T4) across depression...
Article
We resolved displacement on buried stream channels that record the past 3400 years of slip history for the Jordan Gorge (JGF) section of the Dead Sea fault in Israel. Based on three-dimensional (3D) trenching, slip in the past millennium amounts to only 2.7 m, similar to that determined in previous studies, whereas the previous millennium experienc...
Conference Paper
The nature and distribution of damage around faults, and its impacts on fault zone properties has been a hot topic of research over the past decade. Understanding the mechanisms that control the formation of off fault damage can shed light on the processes during the seismic cycle, and the nature of fault zone development. Recent published work has...
Conference Paper
We collected a continuous sample of the fault core and 23 samples of the fault zone out to 52 m across the rupture trace of the 2010 M7.2 El Mayor-Cucapah earthquake to characterize the physical damage and chemical transformations associated with this active seismic source. In addition to quantifying fracture intensity from macroscopic analysis, we...