The 2012 Ferrara seismic sequence: Regional crustal structure, earthquake sources, and seismic hazard

2012 ◽  
Vol 39 (19) ◽  
pp. n/a-n/a ◽  
Author(s):  
Luca Malagnini ◽  
Robert B. Herrmann ◽  
Irene Munafò ◽  
Mauro Buttinelli ◽  
Mario Anselmi ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Crustal Structure ◽  
Seismic Sequence ◽  
Earthquake Sources

Challenges and Opportunities in Turning Large U.S. Archives of Analog Seismograms into a Modern Usable Resource

2020 ◽  
Vol 91 (3) ◽  
pp. 1531-1541
Author(s):  
Paul G. Richards ◽  
Margaret Hellweg
Keyword(s):  
Seismic Hazard ◽  
Scientific Information ◽  
Practical Experience ◽  
Earthquake Physics ◽  
Timing Information ◽  
Earthquake Sources ◽  
Challenges And Opportunities ◽  
Test Ban ◽  
Level Of Effort

Abstract Quantitative seismology is based firmly on the analysis of actual ground motions, and the transition to digital recording in the 1980s enabled sophisticated new capabilities to extract useful results from waveforms. With some effort, these tools can also be applied to analog records. Focusing on assets available within U.S. institutions, we review the necessary steps and the challenges in enabling “data rescue”—that is, preserving the scientific information latent in large analog seismogram archives and making it usable. They include: determining what assets are available (the analog seismogram archives held by various institutions, with associated metadata on instrument responses, station locations, and timing information); developing a consensus on the top level of a triage process (which analog records most definitely should be rescued?); deciding the level of quality needed in copying original seismograms to media suitable for digitizing; assessing the relative merits of scanning and digitizing; and, the need for a community service in distributing scans and digital records, as they accumulate. The necessary level of effort can benefit from practical experience. For example, specific studies have used digitized versions of analog recordings to model earthquake sources and assess seismic hazard. Other studies have used them to gain experience with nuclear explosion signals recorded at regional distances, noting that regional signals enable explosions to be monitored down to levels much lower than those attainable teleseismically. The opportunities presented by large archives of analog seismograms include the insights they present to current and future seismologists studying earthquakes and explosions, into the practical areas of assessing seismic hazard, monitoring for test ban compliance down to low explosion yields—and prompt characterization of actual explosions should they occur, as well the traditional academic pursuit of a better understanding of earthquake physics.

scholarly journals Integrating faults and past earthquakes into a probabilistic seismic hazard model for peninsular Italy

2017 ◽  
Vol 17 (11) ◽  
pp. 2017-2039 ◽  
Author(s):  
Alessandro Valentini ◽  
Francesco Visini ◽  
Bruno Pace
Keyword(s):  
Seismic Hazard ◽  
Seismic Activity ◽  
Grid Point ◽  
Active Faults ◽  
Gaussian Model ◽  
Probabilistic Seismic Hazard ◽  
Maximum Magnitude ◽  
Slip Rates ◽  
Earthquake Sources ◽  
The Impact

Abstract. Italy is one of the most seismically active countries in Europe. Moderate to strong earthquakes, with magnitudes of up to ∼ 7, have been historically recorded for many active faults. Currently, probabilistic seismic hazard assessments in Italy are mainly based on area source models, in which seismicity is modelled using a number of seismotectonic zones and the occurrence of earthquakes is assumed uniform. However, in the past decade, efforts have increasingly been directed towards using fault sources in seismic hazard models to obtain more detailed and potentially more realistic patterns of ground motion. In our model, we used two categories of earthquake sources. The first involves active faults, and using geological slip rates to quantify the seismic activity rate. We produced an inventory of all fault sources with details of their geometric, kinematic, and energetic properties. The associated parameters were used to compute the total seismic moment rate of each fault. We evaluated the magnitude–frequency distribution (MFD) of each fault source using two models: a characteristic Gaussian model centred at the maximum magnitude and a truncated Gutenberg–Richter model. The second earthquake source category involves grid-point seismicity, with a fixed-radius smoothed approach and a historical catalogue were used to evaluate seismic activity. Under the assumption that deformation is concentrated along faults, we combined the MFD derived from the geometry and slip rates of active faults with the MFD from the spatially smoothed earthquake sources and assumed that the smoothed seismic activity in the vicinity of an active fault gradually decreases by a fault-size-driven factor. Additionally, we computed horizontal peak ground acceleration (PGA) maps for return periods of 475 and 2475 years. Although the ranges and gross spatial distributions of the expected accelerations obtained here are comparable to those obtained through methods involving seismic catalogues and classical zonation models, the spatial pattern of the hazard maps obtained with our model is far more detailed. Our model is characterized by areas that are more hazardous and that correspond to mapped active faults, while previous models yield expected accelerations that are almost uniformly distributed across large regions. In addition, we conducted sensitivity tests to determine the impact on the hazard results of the earthquake rates derived from two MFD models for faults and to determine the relative contributions of faults versus distributed seismic activity. We believe that our model represents advancements in terms of the input data (quantity and quality) and methodology used in the field of fault-based regional seismic hazard modelling in Italy.

Crustal Structure, Intraplate Seismicity, and Seismic Hazard in the Mid‐Atlantic United States

2017 ◽  
Vol 89 (1) ◽  
pp. 241-252 ◽  
Author(s):  
L. Soto‐Cordero ◽  
A. Meltzer ◽  
J. C. Stachnik
Keyword(s):  
United States ◽  
Seismic Hazard ◽  
Crustal Structure ◽  
Intraplate Seismicity

A simple algorithm for tracing synthetic isoseismals

1996 ◽  
Vol 86 (4) ◽  
pp. 1019-1027 ◽  
Author(s):  
Livio Sirovich
Keyword(s):  
Seismic Hazard ◽  
Simple Algorithm ◽  
Hazard Maps ◽  
Attenuation Relations ◽  
Seismic Hazard Maps ◽  
Earthquake Sources ◽  
Modeling Techniques ◽  
San Fernando ◽  
Synthetic Isoseismals

Abstract Probabilistic calculation of regional seismic hazard maps also requires the use of the so-called “attenuation relations,” which give the reference “shake-ability” at certain distances from the earthquake sources. This article achieves progress in this area. In fact, the present tests on a series of earthquakes in California (San Fernando, 1971; Whittier Narrows, 1987; Northridge, 1994) suggest that in some regions the areal shapes of the territories damaged by past earthquakes may be synthetically traced—sometimes amazingly well—with a simple algorithm that considers some gross features of the sources, and this is compatible with theory. It seems that this algorithm gives rather stable results. Moreover, when the detailed modeling techniques available nowadays are inapplicable due to lack of data, or for purpose of saving time and money, it might be useable for improving seismic hazard calculations and, conversely, for retrieving information about sources of earthquakes from the preinstrumental era.

scholarly journals The Campotosto linkage fault zone between the 2009 and 2016 seismic sequences of central Italy: Implications for seismic hazard analysis

2020 ◽  
Author(s):  
Emanuele Tondi ◽  
Danica Jablonská ◽  
Tiziano Volatili ◽  
Maddalena Michele ◽  
Stefano Mazzoli ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Fault Zone ◽  
Central Italy ◽  
Seismic Events ◽  
Seismic Gap ◽  
Seismic Zone ◽  
Seismic Sequence ◽  
Geological Evidence ◽  
Seismic Sequences ◽  
Seismogenic Faults

In the last decade central Italy was struck by devastating seismic sequences resulting in hundreds of casualties (i.e., 2009-L′Aquila moment magnitude [Mw] = 6.3, and 2016-Amatrice-Visso-Norcia Mw max = 6.5). These seismic events were caused by two NW-SE−striking, SW-dipping, seismogenic normal faults that were modeled based on the available focal mechanisms and the seismic moment computed during the relative mainshocks. The seismogenic faults responsible for the 2009-L′Aquila Mw = 6.3 (Paganica Fault—PF) and 2016-Amatrice-Visso-Norcia Mw max = 6.5 (Monte Vettore Fault—MVF) are right-stepping with a negative overlap (i.e., underlap) located at the surface in the Campotosto area. This latter was affected by seismic swarms with magnitude ranging from 5.0 to 5.5 during the 2009 seismic sequence and then in 2017 (i.e., a few months later than the mainshocks related with the 2016 seismic sequence). In this paper, the seismogenic faults related to the main seismic events that occurred in the Campotosto Seismic Zone (CSZ) were modeled and interpreted as a linkage fault zone between the PF and MVF interacting seismogenic faults. Based on the underlap dimension, the seismogenic potential of the CSZ is in the order of Mw = 6.0, even in the case that all the faults belonging to the zone were activated simultaneously. This has important implications for seismic hazard assessment in an area dominated by the occurrence of a major NW-SE−striking extensional structure, i.e., the Monte Gorzano Fault (MGF). Mainly due to its geomorphologic expression, this fault has been considered as an active and silent structure (therefore representing a seismic gap) able to generate an earthquake of Mw max = 6.5−7.0. However, the geological evidence provided with this study suggests that the MGF is of early (i.e., pre- to syn-thrusting) origin. Therefore, the evaluation of the seismic hazard in the Campotosto area should not be based on the geometrical characteristics of the outcropping MGF. This also generates substantial issues with earthquake geological studies carried out prior to the recent seismic events in central Italy. More in general, the 4-D high-resolution image of a crustal volume hosting an active linkage zone between two large seismogenic structures provides new insights into the behavior of interacting faults in the incipient stages of connection.

scholarly journals Earthquake sources and seismic hazard in Southeastern Sicily

2009 ◽  
Vol 44 (4) ◽  
Author(s):  
M. S. Barbano ◽  
R. Rigano
Keyword(s):  
Seismic Hazard ◽  
Earthquake Sources

scholarly journals Active faults of the Kerch’s Peninsula: new results

2019 ◽  
Vol 488 (4) ◽  
pp. 408-412
Author(s):  
А. N. Ovsyuchenko ◽  
R. N. Vakarchuk ◽  
A. M. Korzhenkov ◽  
A. S. Larkov ◽  
А. I. Sysolin ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Strong Earthquake ◽  
Late Holocene ◽  
Active Fault ◽  
Active Faults ◽  
Fault Zones ◽  
Strong Earthquakes ◽  
Earthquake Sources ◽  
Kerch Peninsula ◽  
Seismotectonic Model

In the paper there are results of a recent study of the active faults in the Kerch Peninsula. There was compiled a Map of Active Faults - sources of the strong earthquakes occurred in Late Holocene. The map is a regional seismotectonic model of strong earthquake sources - detailed basis for a spatial prognosis of the seismic hazard. Results of the study show that the Kerch Peninsula demonstrates signs of the classical morphostructures, and a morphology of the modern peninsula contours is caused by the large active fault zones.

scholarly journals Integrating faults and past earthquakes into a probabilistic seismic hazard model for peninsular Italy

2017 ◽  
Author(s):  
Alessandro Valentini ◽  
Francesco Visini ◽  
Bruno Pace
Keyword(s):  
Seismic Hazard ◽  
Seismic Activity ◽  
Active Faults ◽  
Gaussian Model ◽  
Probabilistic Seismic Hazard ◽  
Maximum Magnitude ◽  
Ground Acceleration ◽  
Slip Rates ◽  
Earthquake Sources ◽  
The Impact

Abstract. Italy is one of the most seismically active countries in Europe. Moderate to strong earthquakes, with magnitudes of up to ~ 7, have been recorded on many of active faults in historical times. Currently, probabilistic seismic hazard assessments in Italy are mainly based on area source models, in which the seismicity is modelled on a number of seismotectonic zones and the occurrence of earthquakes is assumed to be uniform. However, in the last decade, efforts have increasingly been directed towards using fault sources in seismic hazard models to obtain more detailed and possibly more realistic patterns of ground motion. In our model, we used two categories of earthquake sources. The first involves active faults, and fault slip rates were used to quantify the seismic activity rate. We produced an inventory of all fault sources, with details on their geometric, kinematic and energetic properties. The parameters are used to compute the total seismic moment rate for each fault. We evaluated the magnitude-frequency distributions of each fault source using two models, a characteristic Gaussian model centred on the maximum magnitude and a Truncated Gutenberg-Richter model. The second earthquake source category involves distributed seismicity, and a fixed-radius smoothed approach and a historical catalogue were used to evaluate seismic activity. Under the assumption that deformation is concentrated along faults, we combined the earthquakes derived from the geometry and slip rates of active faults with the earthquakes from the spatially smoothed earthquake sources and assumed that the smoothed seismic activity in the vicinity of an active fault gradually decreases by a fault-size driven factor. We computed horizontal peak ground acceleration maps for return periods of 475 and 2,475 yr. Although the range and gross spatial distribution of the expected accelerations obtained here are comparable to those obtained through methods involving seismic catalogues and classical zonation models, the spatial pattern of our model is far more detailed. Our model is characterized by areas that are more hazardous and that correspond to mapped active faults, while the previous models yield expected accelerations that are almost uniformly distributed across large regions. In addition, we conducted sensitivity tests to determine the impact on the hazard results of the earthquake rates derived from two magnitude-frequency distribution models for faults and to determine the relative contributions of faults versus distributed seismic activity. We think our model represents an advance for Italy in terms of input data (quantity and quality) and methodology in the field of the fault-based regional seismic hazard modelling.

scholarly journals Revisiting seismic hazard assessment for Peninsular Malaysia using deterministic and probabilistic approaches

2018 ◽  
Vol 18 (9) ◽  
pp. 2387-2408 ◽  
Author(s):  
Daniel Weijie Loi ◽  
Mavinakere Eshwaraiah Raghunandan ◽  
Varghese Swamy
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Seismic Hazard Assessment ◽  
B Value ◽  
Peninsular Malaysia ◽  
Point Sources ◽  
Ground Acceleration ◽  
Earthquake Sources ◽  
Source Models ◽  
Pertinent Information

Abstract. Seismic hazard assessments, both deterministic and probabilistic, for Peninsular Malaysia have been carried out using peak ground acceleration (PGA) data recorded between 2004 and 2016 by the Malaysian Meteorological Department using triaxial accelerometers placed at 19 seismic stations on the peninsula. Seismicity source modelling for the deterministic seismic hazard assessment (DSHA) used historical point sources whereas in the probabilistic (PSHA) approach, line and areal sources were used. The earthquake sources comprised the Sumatran subduction zone (SSZ), Sumatran fault zone (SFZ) and local intraplate (LI) faults. Gutenberg–Richter law b value for the various zones identified within the SSZ ranged between 0.56 and 1.06 (mean=0.82) and for the zones within the SFZ, between 0.57 and 1.03 (mean=0.89). Suitable ground motion prediction equations (GMPEs) for Peninsular Malaysia along with other pertinent information were used for constructing a logic tree for PSHA of the region. The DSHA “critical-worst” scenario suggests PGAs of 0.07–0.80 ms−2 (0.7–8.2 percent g), whilst the PSHA suggests mean PGAs of 0.11–0.55 ms−2 (0.5–5.4 percent g) and 0.20–1.02 ms−2 (1.9–10.1 percent g) at 10 % and 2 % probability of exceedance in 50 years, respectively. DSHA and PSHA, despite using different source models and methodologies, both conclude that the central-western cities of Peninsular Malaysia, located between 2 and 4∘ N, are most susceptible to high PGAs, due to neighbouring active Sumatran sources, SFZ and SSZ. Of the two Sumatran sources, surprisingly, the relatively less active SFZ source with low magnitude seismicity appeared as the major contributor due to its proximity. However, potential hazards due to SSZ mega-earthquakes should not be dismissed. Finally, DSHA performed using the limited LI seismic data from the Bukit Tinggi fault at a reasonable moment magnitude (Mw) value of 5.0 predicted a PGA of ∼0.40 ms−2 at Kuala Lumpur.

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