A High-Resolution Seismic Catalog for the Initial 2019 Ridgecrest Earthquake Sequence: Foreshocks, Aftershocks, and Faulting Complexity

2020 ◽  
Vol 91 (4) ◽  
pp. 1971-1978 ◽  
Author(s):  
David R. Shelly
Keyword(s):  
High Resolution ◽  
Template Matching ◽  
Earthquake Sequence ◽  
Earthquake Catalog ◽  
Surface Rupture ◽  
Initial Portion ◽  
Multiple Fault ◽  
Fault Structures ◽  
Seismic Catalog ◽  
Complex Distribution

Abstract I use template matching and precise relative relocation techniques to develop a high-resolution earthquake catalog for the initial portion of the 2019 Ridgecrest earthquake sequence, from 4 to 16 July, encompassing the foreshock sequence and the first 10+ days of aftershocks following the Mw 7.1 mainshock. Using 13,525 routinely cataloged events as waveform templates, I detect and precisely locate a total of 34,091 events. Precisely located earthquakes reveal numerous crosscutting fault structures with dominantly perpendicular southwest and northwest strikes. Foreshocks of the Mw 6.4 event appear to align on a northwest-striking fault. Aftershocks of the Mw 6.4 event suggest that it further ruptured this northwest-striking fault, as well as the southwest-striking fault where surface rupture was observed. Finally, aftershocks of the Mw 7.1 show a highly complex distribution, illuminating a primary northwest-striking fault zone consistent with surface rupture but also numerous crosscutting southwest-striking faults. Aftershock relocations suggest that the Mw 7.1 event ruptured adjacent to the previous northwest-striking rupture of the Mw 6.4, perhaps activating a subparallel structure southwest of the earlier rupture. Both the northwest and southeast rupture termini of the Mw 7.1 rupture exhibited multiple fault branching, with particularly high rates of aftershocks and multiple fault orientations in the dilatational quadrant northeast of the northwest rupture terminus.

A high-resolution seismic catalog for the 2020 Magna, Utah, earthquake sequence

2020 ◽  
Author(s):  
Guanning Pang ◽  
Keith Koper ◽  
Maria Mesimeri ◽  
Kristine Pankow ◽  
Benjamin Baker ◽  
...  
Keyword(s):  
High Resolution ◽  
Earthquake Sequence ◽  
Seismic Catalog

scholarly journals Machine-Learning-Based High-Resolution Earthquake Catalog Reveals How Complex Fault Structures Were Activated during the 2016–2017 Central Italy Sequence

2021 ◽  
Vol 1 (1) ◽  
pp. 11-19
Author(s):  
Yen Joe Tan ◽  
Felix Waldhauser ◽  
William L. Ellsworth ◽  
Miao Zhang ◽  
Weiqiang Zhu ◽  
...  
Keyword(s):  
Central Italy ◽  
Normal Fault ◽  
Earthquake Sequence ◽  
Fault System ◽  
Earthquake Catalog ◽  
Earthquake Triggering ◽  
Aftershock Activity ◽  
Arrival Times ◽  
Complex Fault ◽  
Fault Structures

Abstract The 2016–2017 central Italy seismic sequence occurred on an 80 km long normal-fault system. The sequence initiated with the Mw 6.0 Amatrice event on 24 August 2016, followed by the Mw 5.9 Visso event on 26 October and the Mw 6.5 Norcia event on 30 October. We analyze continuous data from a dense network of 139 seismic stations to build a high-precision catalog of ∼900,000 earthquakes spanning a 1 yr period, based on arrival times derived using a deep-neural-network-based picker. Our catalog contains an order of magnitude more events than the catalog routinely produced by the local earthquake monitoring agency. Aftershock activity reveals the geometry of complex fault structures activated during the earthquake sequence and provides additional insights into the potential factors controlling the development of the largest events. Activated fault structures in the northern and southern regions appear complementary to faults activated during the 1997 Colfiorito and 2009 L’Aquila sequences, suggesting that earthquake triggering primarily occurs on critically stressed faults. Delineated major fault zones are relatively thick compared to estimated earthquake location uncertainties, and a large number of kilometer-long faults and diffuse seismicity were activated during the sequence. These properties might be related to fault age, roughness, and the complexity of inherited structures. The rich details resolvable in this catalog will facilitate continued investigation of this energetic and well-recorded earthquake sequence.

Seismic rate change as a tool to investigate remote triggering of the 2010-2011 Canterbury earthquake sequence, New Zealand

2020 ◽  
Author(s):  
Yifan Yin ◽  
Stefan Wiemer ◽  
Edi Kissling ◽  
Federica Lanza ◽  
Bill Fry
Keyword(s):  
New Zealand ◽  
High Resolution ◽  
Template Matching ◽  
Human Life ◽  
B Value ◽  
Earthquake Sequence ◽  
Support Vector ◽  
Plate Boundaries ◽  
The North ◽  
Canterbury Earthquake Sequence

<p>Crustal earthquakes in low deform rate regions are rare in the human life span but bear heavy losses when occurring. Limited observations also hinter robust earthquake forecasts. In this study, we use a high-resolution catalog to investigate the triggering of the 2010-2011 Canterbury earthquake sequence, New Zealand. The seismic sequence occurred in the North Canterbury Plains, a low-stress, low-seismicity region relatively close to active plate boundaries where large earthquakes are frequent, such as the 2009 M<sub>W</sub> 7.8 Dusky Sound Earthquake. To map the post-seismic stress transfers of remote large events acting in the region, we calculate the temporal and spatial seismic rate changes in the crust from 2005 to the 2010 Mw 7.1 Darfield Earthquake, the first mainshock of the Canterbury sequence. We use template matching analysis to obtain a new high-resolution seismic catalog that includes events previously undetected by routine network monitoring. Detection quality is further established through the usage of a Support Vector Machine classifier. Using the new catalog, we observe a seismic quiescence on the North Canterbury Plain between Dusky Sound Earthquake and the Darfield Earthquake. The quiescence is accompanied by a reduced rate in micro-seismicity, suggesting a lowered b-value in the region primed for the Canterbury sequence. The lack of proof of dynamic or static triggering suggests that complex fault interactions lead to the onset of the Darfield Earthquake.</p>

scholarly journals Lane-Level Road Extraction from High-Resolution Optical Satellite Images

2019 ◽  
Vol 11 (22) ◽  
pp. 2672
Author(s):  
Jiguang Dai ◽  
Tingting Zhu ◽  
Yilei Zhang ◽  
Rongchen Ma ◽  
Wantong Li
Keyword(s):  
High Resolution ◽  
Rural Areas ◽  
Template Matching ◽  
City Planning ◽  
Urban Expansion ◽  
Satellite Image ◽  
Road Extraction ◽  
Urban And Rural Areas ◽  
Optical Satellite Images ◽  
Vehicle Management

High-quality updates of road information play an important role in smart city planning, sustainable urban expansion, vehicle management, urban planning, traffic navigation, public health and other fields. However, due to interference from road geometry and texture noise, it is difficult to avoid the decline of automation while accurately extracting roads. Therefore, we propose a high-resolution optical satellite image lane-level road extraction method. First, from the perspective of template matching and considering road characteristics and relevant semantic relations, an adaptive correction model, an MLSOH (multi-scale line segment orientation histogram) descriptor, a sector descriptor, and a multiangle beamlet descriptor are proposed to solve the interference from geometry and texture noise in road template matching and tracking. Second, based on refined lane-level tracking, single-lane and double-lane road-tracking modes are designed to extract single-lane and double-lane roads, respectively. In this paper, Pleiades satellite and GF-2 images are selected to set up different scenarios for urban and rural areas. Experiments are carried out on the phenomena that restrict road extraction, such as tree occlusion, building shadow occlusion, road bending, and road boundary blurring. Compared with other methods, the proposed method not only ensures the accuracy of lane-level road extraction but also greatly improves the automation of road extraction.

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