Seismic depth imaging of normal faulting in the southern Death Valley Basin

Geophysics ◽  
1998 ◽  
Vol 63 (1) ◽  
pp. 223-230 ◽  
Author(s):  
Sergio Chávez‐Pérez ◽  
John N. Louie ◽  
Sathish K. Pullammanappallil
Keyword(s):  
Normal Fault ◽  
Velocity Model ◽  
Death Valley ◽  
Normal Faults ◽  
Normal Faulting ◽  
Lateral Velocity ◽  
Western Basin ◽  
Depth Imaging ◽  
Arrival Times ◽  
Velocity Variations

Motivated by the need to image faults to test Cenozoic extension models for the Death Valley region of the western basin and range province, an area of strong lateral velocity variations, we examine the geometry of normal faulting in southern Death Valley by seismic depth imaging. We analyze COCORP Death Valley Line 9 to attain an enhanced image of shallow fault structure to 2.5 km depth. Previous work used standard seismic processing to infer normal faults from bed truncations, displacement of horizontal reflectors, and diffractions. We obtain a detailed velocity model by nonlinear optimization of first‐ arrival times picked from shot gathers, examine the unprocessed data for fault reflections, and use a Kirchhoff prestack depth imaging procedure to handle lateral velocity variations and arbitrary dips properly. Fault‐plane reflections reveal the listric true‐depth geometry of the normal fault at the Black Mountains range front in southern Death Valley. This is consistent with the concept of low‐angle extension in this region and strengthens its association with crustal‐scale magmatic plumbing.

scholarly journals A reappraisal of active tectonics along the Fethiye-Burdur trend, southwestern Turkey

2021 ◽  
Author(s):  
Edwin Nissen ◽  
Mussaver Didem Cambaz ◽  
Élyse Gaudreau ◽  
Andrew Howell ◽  
Ezgi Karasözen ◽  
...  
Keyword(s):  
Active Tectonics ◽  
Normal Fault ◽  
Recent Change ◽  
Strike Slip ◽  
Gravitational Potential Energy ◽  
Normal Faults ◽  
Normal Faulting ◽  
Arrival Times ◽  
Anatolian Plateau ◽  
Recent Earthquakes

We investigate active tectonics in southwestern Turkey along the trend between Fethiye, near the eastern end of the Hellenic subduction zone, and Burdur, on the Anatolian plateau. Previously, regional GPS velocity data have been used to propose either (1) a NE-trending zone of strike-slip faulting coined the Fethiye-Burdur Fault Zone, or (2) a mix of uniaxial and radial extension accommodated by normal faults with diverse orientations. We test these models against the available earthquake data, updated in light of recent earthquakes at Acıpayam (20 March 2019, Mw 5.6) and Bozkurt (8 August 2019, Mw 5.8) — the largest in this region in the last two decades — and at Arıcılar (24 November 2017, Mw 5.3). Using Sentinel-1 InSAR and seismic waveforms and arrival times, we show that the Acıpayam, Bozkurt and Arıcılar earthquakes were buried ruptures on pure normal faults with subtle or indistinct topographic expressions. By exploiting ray paths shared with these well-recorded modern events, we relocate earlier instrumental seismicity throughout southwestern Turkey. We find that the 1971 Mw 6.0 Burdur earthquake likely ruptured a NW-dipping normal fault in an area of indistinct geomorphology near Salda Lake, contradicting earlier studies that place it on well-expressed faults bounding the Burdur basin. Overall, the northern Fethiye-Burdur trend is characterized by orthogonal normal faulting, consistent with radial extension and likely responsible for the distinct physiography of Turkey's 'Lake District'. The southern Fethiye-Burdur trend is dominated by ESE-WNW trending normal faulting, even though most faults evident in the topography strike NE-SW. This hints at a recent change in regional strain, perhaps related to eastward propagation of the Gökova graben into the area or to rapid subsidence of the Rhodes basin. Overall, our results support GPS-derived tectonic models that depict a mix of uniaxial and radial extension throughout southwestern Turkey, with no evidence for major, active strike-slip faults anywhere along the Fethiye-Burdur trend. Normal faulting orientations are consistent with a stress field driven primarily by contrasts in gravitational potential energy between the elevated Anatolian plateau and the low-lying Rhodes and Antalya basins.

The 4 December 2015 Mw 7.1 Normal-Faulting Antarctic Plate Earthquake and Its Seismotectonic Implications

2020 ◽  
Vol 110 (3) ◽  
pp. 1090-1100
Author(s):  
Ronia Andrews ◽  
Kusala Rajendran ◽  
N. Purnachandra Rao
Keyword(s):  
Body Wave ◽  
Focal Depth ◽  
Normal Fault ◽  
Normal Faults ◽  
Oceanic Plate ◽  
Normal Faulting ◽  
Transform Faults ◽  
Wave Inversion ◽  
Spreading Ridges ◽  
Southeast Indian Ridge

ABSTRACT Oceanic plate seismicity is generally dominated by normal and strike-slip faulting associated with active spreading ridges and transform faults. Fossil structural fabrics inherited from spreading ridges also host earthquakes. The Indian Oceanic plate, considered quite active seismically, has hosted earthquakes both on its active and fossil fault systems. The 4 December 2015 Mw 7.1 normal-faulting earthquake, located ∼700  km south of the southeast Indian ridge in the southern Indian Ocean, is a rarity due to its location away from the ridge, lack of association with any mapped faults and its focal depth close to the 800°C isotherm. We present results of teleseismic body-wave inversion that suggest that the earthquake occurred on a north-northwest–south-southeast-striking normal fault at a depth of 34 km. The rupture propagated at 2.7  km/s with compact slip over an area of 48×48  km2 around the hypocenter. Our analysis of the background tectonics suggests that our chosen fault plane is in the same direction as the mapped normal faults on the eastern flanks of the Kerguelen plateau. We propose that these buried normal faults, possibly the relics of the ancient rifting might have been reactivated, leading to the 2015 midplate earthquake.

Passive seismic tomography using recorded microseismicity: Application to mining-induced seismicity

Geophysics ◽  
2019 ◽  
Vol 84 (1) ◽  
pp. B41-B57 ◽  
Author(s):  
Himanshu Barthwal ◽  
Mirko van der Baan
Keyword(s):  
Seismic Tomography ◽  
Velocity Model ◽  
P Wave ◽  
Double Difference ◽  
Lateral Velocity ◽  
Study Region ◽  
Arrival Times ◽  
3D Velocity Model ◽  
Passive Seismic ◽  
Dip Angle

Microseismicity is recorded during an underground mine development by a network of seven boreholes. After an initial preprocessing, 488 events are identified with a minimum of 12 P-wave arrival-time picks per event. We have developed a three-step approach for P-wave passive seismic tomography: (1) a probabilistic grid search algorithm for locating the events, (2) joint inversion for a 1D velocity model and event locations using absolute arrival times, and (3) double-difference tomography using reliable differential arrival times obtained from waveform crosscorrelation. The originally diffusive microseismic-event cloud tightens after tomography between depths of 0.45 and 0.5 km toward the center of the tunnel network. The geometry of the event clusters suggests occurrence on a planar geologic fault. The best-fitting plane has a strike of 164.7° north and dip angle of 55.0° toward the west. The study region has known faults striking in the north-northwest–south-southeast direction with a dip angle of 60°, but the relocated event clusters do not fall along any mapped fault. Based on the cluster geometry and the waveform similarity, we hypothesize that the microseismic events occur due to slips along an unmapped fault facilitated by the mining activity. The 3D velocity model we obtained from double-difference tomography indicates lateral velocity contrasts between depths of 0.4 and 0.5 km. We interpret the lateral velocity contrasts in terms of the altered rock types due to ore deposition. The known geotechnical zones in the mine indicate a good correlation with the inverted velocities. Thus, we conclude that passive seismic tomography using microseismic data could provide information beyond the excavation damaged zones and can act as an effective tool to complement geotechnical evaluations.

Overthrust imaging with tomo‐datuming: A case study

Geophysics ◽  
1998 ◽  
Vol 63 (1) ◽  
pp. 25-38 ◽  
Author(s):  
Xianhuai Zhu ◽  
Burke G. Angstman ◽  
David P. Sixta
Keyword(s):  
Velocity Model ◽  
Surface Velocity ◽  
Time Shift ◽  
Lateral Velocity ◽  
Prestack Depth Migration ◽  
Near Surface ◽  
Depth Migration ◽  
Static Corrections ◽  
Velocity Variations ◽  
Kirchhoff Method

Through the use of iterative turning‐ray tomography followed by wave‐equation datuming (or tomo‐datuming) and prestack depth migration, we generate accurate prestack images of seismic data in overthrust areas containing both highly variable near‐surface velocities and rough topography. In tomo‐datuming, we downward continue shot records from the topography to a horizontal datum using velocities estimated from tomography. Turning‐ray tomography often provides a more accurate near‐surface velocity model than that from refraction statics. The main advantage of tomo‐datuming over tomo‐statics (tomography plus static corrections) or refraction statics is that instead of applying a vertical time‐shift to the data, tomo‐datuming propagates the recorded wavefield to the new datum. We find that tomo‐datuming better reconstructs diffractions and reflections, subsequently providing better images after migration. In the datuming process, we use a recursive finite‐difference (FD) scheme to extrapolate wavefield without applying the imaging condition, such that lateral velocity variations can be handled properly and approximations in traveltime calculations associated with the raypath distortions near the surface for migration are avoided. We follow the downward continuation step with a conventional Kirchhoff prestack depth migration. This results in better images than those migrated from the topography using the conventional Kirchhoff method with traveltime calculation in the complicated near surface. Since FD datuming is only applied to the shallow part of the section, its cost is much less than the whole volume FD migration. This is attractive because (1) prestack depth migration usually is used iteratively to build a velocity model, so both efficiency and accuracy are important factors to be considered; and (2) tomo‐datuming can improve the signal‐to‐noise (S/N) ratio of prestack gathers, leading to more accurate migration velocity analysis and better images after depth migration. Case studies with synthetic and field data examples show that tomo‐datuming is especially helpful when strong lateral velocity variations are present below the topography.

scholarly journals The 2013–2018 Matese and Beneventano Seismic Sequences (Central–Southern Apennines): New Constraints on the Hypocentral Depth Determination

Geosciences ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 17
Author(s):  
Brando Trionfera ◽  
Alberto Frepoli ◽  
Gaetano De Luca ◽  
Pasquale De Gori ◽  
Carlo Doglioni
Keyword(s):  
Strong Motion ◽  
Normal Fault ◽  
Historical Earthquakes ◽  
Velocity Model ◽  
Southern Apennines ◽  
S Wave ◽  
Fault Plane Solutions ◽  
Arrival Times ◽  
Brittle Ductile Transition ◽  
Seismogenic Structures

The Matese and Beneventano areas coincide with the transition from the central to the southern Apennines and are characterized by both SW- and NE-dipping normal faulting seismogenic structures, responsible for the large historical earthquakes. We studied the Matese and Beneventano seismicity by means of high-precision locations of earthquakes spanning from 29 December 2013 to 4 September 2018. Events were located by using all of the available data from temporary and permanent stations in the area and a 1D computed velocity model, inverting the dataset with the Velest code. For events M > 2.8 we used P- and S-waves arrival times of the strong motion stations located in the study area. A constant value of 1.83 for Vp/Vs was computed with a modified Wadati method. The dataset consists of 2378 earthquakes, 18,715 P- and 12,295 S-wave arrival times. We computed 55 new fault plane solutions. The mechanisms show predominantly normal fault movements, with T-axis trends oriented NE–SW. Only relatively small E–W trending clusters in the eastern peripheral zones of the Apenninic belt show right-lateral strike-slip kinematics similar to that observed in the Potenza (1990–1991) and Molise (2002 and 2018) sequences. These belong to transfer zones associated with differential slab retreat of the Adriatic plate subduction beneath the Apennines. The Matese sequence (December 2013–February 2014; main shock Mw 5.0) is the most relevant part of our dataset. Hypocentral depths along the axis of the Apenninic belt are in agreement with previous seismological studies that place most of the earthquakes in the brittle upper crust. We confirm a general deepening of seismicity moving from west to the east along the Apennines. Seismicity depth is controlled by heat-flow, which is lower in the eastern side, thus causing a deeper brittle–ductile transition.

scholarly journals Potentially active normal faulting zone identified in the eastern margin of Palu City, Central Sulawesi, Indonesia

2021 ◽  
Vol 873 (1) ◽  
pp. 012071
Author(s):  
Anggraini Rizkita Puji ◽  
Mudrik Rahmawan Daryono ◽  
Danny Hilman Natawidjaja
Keyword(s):  
Active Faults ◽  
Digital Terrain Model ◽  
Slip Rate ◽  
Normal Fault ◽  
Provincial Government ◽  
Economic Losses ◽  
Normal Faults ◽  
Normal Faulting ◽  
Eastern Margin ◽  
Central Sulawesi

Abstract The 2018 Mw 7.5 earthquake in Palu, Central Sulawesi, resulting in ~2,000 fatalities and estimated economic losses of ~22.8 trillion Indonesian Rupiah, according to the report of BAPPENAS and Central Sulawesi Provincial-Government. Therefore, it is necessary to prevent similar disaster in the future by further detailed studies of any other potential sources that are capable of generating such hazards. Palu City is in the vast depression valley bordered by mountains in its eastern and western margins. The 2018 earthquake source is the Palukoro Fault, which runs through the western margin of onshore Palu Valley then continued under the bay. Along the eastern margin of the valley, we also identified a wide zone of many potentially active faults strands orienting N-S and NW-SE, showing predominantly normal faulting. These faults are observed from their normal fault scarps as inspected from Light Detection and Ranging Digital Terrain Model (LiDAR DTM) data with 90-cm resolution and field ground checks. The faults deformed the old terrace sediments (Late Pleistocene, ~125 kya), but it is unclear whether they also cut the Holocene young alluvial like the ruptured fault of 2018 event. Further paleoseismology investigation is then necessary to obtain further information about these potentially-active normal faults, including their slip-rate and the past ruptures.

Lake Charles, Louisiana, earthquake of 16 October 1983

1988 ◽  
Vol 78 (4) ◽  
pp. 1463-1474
Author(s):  
Donald A. Stevenson ◽  
James D. Agnew
Keyword(s):  
Gulf Coast ◽  
Normal Fault ◽  
Velocity Model ◽  
Strike Slip ◽  
Crystalline Basement ◽  
P Wave ◽  
Normal Faulting ◽  
Significant Evidence ◽  
Lake Charles ◽  
East West

Abstract On 16 October 1983, at 19:40 (UTC), a magnitude 3.8 earthquake occurred near Lake Charles in southwestern Louisiana. The earthquake was felt over an area of 2600 km2 and had a maximum Modified Mercalli intensity of V. This was the first significant Louisiana Gulf Coast earthquake to be recorded and located by nearby microseismic networks. One possible foreshock and three aftershocks also were recorded and located using a velocity model developed for this study. The focal mechanism of the earthquake was determined based on P-wave first motions from 22 local and regional stations. The solution indicates a predominantly east-west trending, southeast-dipping normal fault with a small strike-slip component. The depth of this event (14+ km) provides the first significant evidence that normal faulting within the crystalline basement may control shallower growth faults along the Gulf Coast.

Synorogenic extension in the Tethyan Himalaya documented by structural studies and the Kübler index, Lachung La area, NW India

Clay Minerals ◽  
2001 ◽  
Vol 36 (2) ◽  
pp. 237-247 ◽  
Author(s):  
M. Girard ◽  
P. Thélin ◽  
A. Steck
Keyword(s):  
Normal Fault ◽  
Metamorphic Grade ◽  
Normal Faults ◽  
Structural Studies ◽  
Normal Faulting ◽  
Kübler Index ◽  
Important Extension ◽  
Layered Clay ◽  
Tethyan Himalaya

AbstractTectonic observations in the Tethyan Himalaya reveal an important extensional event that succeeds the emplacement of SW-verging nappes. A major thrust, called the Kum Tso Thrust, has been backfolded and reactivated by normal faulting associated with this event.Measurements of the Kübler index, coupled with characterization of clay-size paragenesis show the effect of normal faulting on the regional metamorphic zonation and indicate that important extension zones, like the Sarchu-Lachung La Normal Fault Zone (SLFZ), exist within the Tethyan Himalaya. Diagenetic limestones from within the SLFZ are characterized by the occurrence of mixed-layered clay phases, kaolinite and an illite with a 001 peak >0.4 Δ°2θ. This zone is bordered by two anchizonal-to-epizonal zones, where illite peaks become narrower. Further to the NE the successive appearance of biotite, chloritoid, garnet and garnet-staurolite-kyanite assemblages testifies to an increase in metamorphic grade. The cataclastic samples from the normal faults contain kaolinite, smectite and a ‘broad’ illite, indicating that extension occurs under diagenetic conditions.

Seismic depth imaging of normal faulting in the Southern Death Valley basin

1996 ◽  
Author(s):  
Sergio Chávez‐Pérez ◽  
John N. Louie ◽  
Sathish K. Pullammanappallil
Keyword(s):  
Death Valley ◽  
Normal Faulting ◽  
Depth Imaging

Datum correction by wave‐equation extrapolation

Geophysics ◽  
1988 ◽  
Vol 53 (10) ◽  
pp. 1311-1322 ◽  
Author(s):  
V. Shtivelman ◽  
A. Canning
Keyword(s):  
Wave Equation ◽  
Synthetic Data ◽  
Real Data ◽  
Static Solution ◽  
Velocity Model ◽  
Lateral Velocity ◽  
Static Correction ◽  
Slow Velocity ◽  
Velocity Variations ◽  
Seismic Sections

Seismic sections are usually datum corrected by static shifting. For small differences in elevation and slow velocity variations between the input datum and the output datum, static shifting is a sufficiently accurate datum correction procedure. However, for significant differences in elevations and a more complicated velocity model, the accuracy of the static solution may prove to be insufficient; and a more exact method should be used. In this paper, we study the limitations of the static method of datum correction and develop simple and effective extrapolation schemes based on the wave equation, schemes which lead to more accurate datum correction. The distortions of seismic events caused by static correction are illustrated by a number of simple examples. To reduce the distortions, we propose a number of extrapolation schemes based on the asymptories of the Kirchhoff integral solution of the 2-D scalar wave equation. Application of the extrapolation algorithms to synthetic data shows that they provide accurate datum corrections even for a nonplanar input datum and vertical and lateral velocity variations. The algorithms have been successfully applied to real data.

Sign in / Sign up

Export Citation Format

Share Document