Earthquake scenarios: a practical way to handle alternative solutions to historical earthquakes and to increase the transparency of seismic hazard assessment

AbstractSeismic hazard assessment relies on the knowledge of the source characteristics of past earthquakes. Unfortunately, seismic waveform analysis, representing the most powerful tool for the investigation of earthquake source parameters, is only possible for events occurred in the last 100–120 years, i.e., since seismographs with known response function were developed. Nevertheless, during this time significant earthquakes have been recorded by such instruments and today, also thanks to technological progress, these data can be recovered and analysed by means of modern techniques.In this paper, aiming at giving a general sketch of possible analyses and attainable results in historical seismogram studies, I briefly describe the major difficulties in processing the original waveforms and present a review of the results that I obtained from previous seismogram analysis of selected significant historical earthquakes occurred during the first decades of the XXth century, including (A) the December 28, 1908, Messina straits (southern Italy), (B) the June 11, 1909, Lambesc (southern France) – both of which are the strongest ever recorded instrumentally in their respective countries –and (C) the July 13, 1930, Irpinia (southern Italy) events. For these earthquakes, the major achievements are represented by the assessment of the seismic moment (A, B, C), the geometry and kinematics of faulting (B, C), the fault length and an approximate slip distribution (A, C). The source characteristics of the studied events have also been interpreted in the frame of the tectonic environment active in the respective region of interest. In spite of the difficulties inherent to the investigation of old seismic data, these results demonstrate the invaluable and irreplaceable role of historical seismogram analysis in defining the local seismogenic potential and, ultimately, for assessing the seismic hazard. The retrieved information is crucial in areas where important civil engineering works are planned, as in the case of the single-span bridge to be built across the Messina straits and the ITER nuclear fusion power plant to be built in Cadarache, close to the location of the Lambesc event, and in regions characterized by high seismic risk, such as southern Apennines.

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On historical earthquakes in Switzerland: summary of compilations and investigations

Annals of Geophysics ◽

10.4401/ag-3327 ◽

2009 ◽

Vol 47 (2-3) ◽

Author(s):

D. Mayer-Rosa ◽

G. Schwarz-Zanetti

Keyword(s):

Seismic Hazard ◽

Hazard Assessment ◽

Seismic Hazard Assessment ◽

Historical Earthquakes ◽

Macroseismic Data ◽

The Creation ◽

Systematic Collection ◽

Made In

Studies of historical earthquakes in Switzerland are contained in monographs, chronological collections of effects and parametric catalogues. The systematic collection of macroseismic material started with the creation of the Swiss Seismological Commission in 1878. All parametric catalogues since 1975 have been prepared for seismic hazard assessment. The most up-to-date investigation of macroseismic data and compilation into a catalogue (ECOS) was made in the 2002 in context of the re-assessment of seismic hazard for nuclear sites.

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Historical Earthquakes of the Eastern Sunda Arc: Source Mechanisms and Intensity‐Based Testing of Indonesia’s National Seismic Hazard Assessment

Bulletin of the Seismological Society of America ◽

10.1785/0120180085 ◽

2018 ◽

Vol 109 (1) ◽

pp. 43-65 ◽

Cited By ~ 7

Author(s):

Jonathan Griffin ◽

Ngoc Nguyen ◽

Phil Cummins ◽

Athanasius Cipta

Keyword(s):

Seismic Hazard ◽

Hazard Assessment ◽

Seismic Hazard Assessment ◽

Historical Earthquakes ◽

Sunda Arc ◽

Source Mechanisms

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Next-Generation EEW Empowered by NDSHA: From Concept to Implementation

Geosciences ◽

10.3390/geosciences11110473 ◽

2021 ◽

Vol 11 (11) ◽

pp. 473

Author(s):

Yan Zhang ◽

Zhongliang Wu ◽

Fabio Romanelli ◽

Franco Vaccari ◽

Changsheng Jiang ◽

...

Keyword(s):

Seismic Hazard ◽

Hazard Assessment ◽

Early Warning ◽

Seismic Hazard Assessment ◽

Source Area ◽

Active Role ◽

End Users ◽

Economic Losses ◽

Earthquake Scenarios ◽

Unique Decision

In this paper, we discuss a possible combination of Earthquake Early Warning (EEW) and Neo-deterministic Seismic Hazard Assessment (NDSHA), and propose a new warning model, EEW2.0. The aim is to provide a differentiated warning alert to various end-users based on the results of seismic hazard assessment evaluation. The implementation of such a system contains three basic steps: (a) classification of “potential to cause hazard” in terms of magnitude; (b) determination of the source areas and building a hazard database in terms of Modified Mercalli Intensity (MMI) maps, considering all possible earthquake scenarios in the source area, for the whole protected area; (3) equipping unique decision framework for specific end-users. When a damaging earthquake (M ≥ 5.0) is detected, EEW2.0 quickly matches the prepared MMI map by estimated magnitude and epicenter, then directly extracts the MMI value and issues an early warning to the public. With the great attention and resources put into the reduction in seismic and its secondary risk in the 21st century, the proposed EEW2.0 will likely play an active role in protecting lives and reducing economic losses.

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De la neotectónica a la amenaza sísmica en América Latina y el Caribe

Boletín de la Sociedad Geológica Mexicana ◽

10.18268/bsgm2021v73n2p260221 ◽

2021 ◽

Vol 73 (2) ◽

pp. P260221

Author(s):

Laura Perucca ◽

Franck A. Audemard M.

Keyword(s):

Seismic Hazard ◽

Hazard Assessment ◽

Seismic Activity ◽

Seismic Hazard Assessment ◽

Seismic Energy ◽

Sedimentary Basins ◽

Historical Earthquakes ◽

Site Effect ◽

Wave Amplification ◽

Large Earthquakes

Today it is understood that the seismic risk, as well as any type of risk, is proportional to the disastrous combination of the seismic threat and the vulnerability of the exposed systems. Considering that the seismic threat is of natural origin, therefore not modifiable or controllable by man to any extent - unlike other threats that are anthropic or generated by man himself (eg nuclear explosions, seismicity induced by dams or reservoirs of water, etc.) if they are-, risk reduction is achieved both by increasing resilience (a system's own capacity to recover from an adverse event) and by reducing the exposure of potentially exposed systems. However, it should be noted that risk can be better characterized and quantified if the threat is better defined and known, even though it cannot be controlled. That is why the seismic threat needs to be the best bounded, measured and defined, to the extent of the available information, in order to reduce uncertainties to the maximum. It then requires that the seismic activity of the region under study be studied in detail, which also implies identifying and characterizing the generating sources of these earthquakes (seismogenic faults); that is, the geological faults responsible for such seismicity (seismotectonic association; Figure 1). It is customary in seismic hazard studies to study both aspects (source faults and seismicity) in a radius of at least 200 km; distance resulting from the attenuation of seismic energy as it propagates through the medium. So it is understood that the seismic energy released during most large earthquakes is expected to be attenuated to low hazard levels at that distance. The built environment located in sedimentary basins filled with soft or little consolidated sediments, such as the cases of Mexico City and Caracas, probably escape this practice, due to wave amplification effects as a site effect, which could be excited by large shallow or shallow earthquakes. subduction, with epicenters beyond that distance prescribed by practice. Consequently, it is necessary to retrace the seismic history –or earthquake chronology, which is the sum of the instrumental, historical and pre-historical earthquakes that make up the entire seismic activity (Audemard, 2019) - of the region surrounding the site. subject to a seismic hazard assessment (EAS; in English, Seismic hazard Assessment -SHA-), in the most complete way, as well as extensive in the time possible, in order to determine two fundamental parameters when calculating said estimate: the Maximum probable earthquake and the return period of large earthquakes with destructive capacity, for each of the identified faults, or their individual segments if they are defined. Given that these EAS can be addressed by two approaches, probabilistic and deterministic (or various combinations of both), the longest in time is the evaluated period, the statistical evaluations of both parameters indicated above - known under the term of seismogenic potential- , they will be more robust and reliable to estimate the seismic threat.

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