scholarly journals The 1791 magnitude (Mw) 5.5 earthquake, Charlevoix, Quebec: interpretation of macroseismic information

2020 ◽  
Author(s):  
M Lamontagne
Keyword(s):  
Macroseismic Information

scholarly journals Evaluation of 1947-1993 macroseismic information in Portugal using the EMS-92 scale

1996 ◽  
Vol 39 (5) ◽  
Author(s):  
A. Paula ◽  
C. S. Oliveira
Keyword(s):  
Quality Factor ◽  
Intensity Scale ◽  
Macroseismic Information

In the present work macroseismic information of the earthquakes felt in Continental Portugal from 1947 to 1993 was evaluated using the EMS-92 intensity scale. Press information, and data in the seismological questionnaires used in this period of time, were used as prime information. Prior intensity assignments were also used in the analysis. Two methodologies -A and B -were followed, according to the type of information available: A) whenever seismological questionnaires or descriptions of effects are accessed this information was analysed leading to an intensity value and to an intensity quality factor; this methodology includes a standardisation of questionnaire evaluation, through the use of conversion keys; B) if only an intensity assignment, in any known scale, existed, then a conversion of intensities was made. The results of these two methodologies are compared and discussed. Based on the above mentioned information a database with 1947-1993 Portuguese seismic information was built up, and a few features of its contents were discussed.

scholarly journals Re-evaluation of early instrumental earthquake locations: methodology and examples

2009 ◽  
Vol 47 (2-3) ◽  
Author(s):  
R. D. Adams
Keyword(s):  
Focal Depth ◽  
Phase Identification ◽  
Earth Structure ◽  
Maximum Phase ◽  
The Core ◽  
Hindu Kush ◽  
Instrumental Period ◽  
The Right ◽  
Macroseismic Information ◽  
Main Model

The difficulties of locating earthquakes in the early instrumental period are not always fully appreciated. The networks were sparse, and the instruments themselves were of low gain, often had inappropriate frequency response and recording resolution, and their timing could be unreliable and inaccurate. Additionally, there was only limited knowledge of earth structure and consequent phase identification and propagation. The primitive Zöppritz tables for P and S, with no allowance for the core, did not come into use until 1907, and remained the main model until the adoption of the Jeffreys-Bullen tables in the mid-1930s. It was not until the early 1920s that studies of Hindu Kush earthquakes revealed that earthquake foci could have significant depth. Although many early locations are creditably accurate, others can be improved by use of more modern techniques. Early earthquakes in unusual places often repay closer investigation. Many events after about 1910 are well enough recorded to be re-located by computer techniques, but earlier locations can still be improved by using more recent knowledge and simpler techniques, such as phase re-identification and graphical re-location. One technique that helps with early events is to locate events using the time of the maximum phase of surface waves, which is often well reported. Macroseismic information is also valuable in giving confirmation of earthquake positions or helping to re-assess them, including giving indications of focal depth. For many events in the early instrumental period macroseismic locations are to be preferred to the poorly-controlled instrumental ones. Macroseismic locations can also make useful trial origins for computer re-location. Even more recent events, which appear to be well located, may be grossly in error due to mis-interpretation of phases and inadequate instrumental coverage. A well converging mathematical solution does not always put the earthquake in the right place, and computer location programs may give unrealistically small estimates of error. Examples are given of improvements in locations of particular earthquakes in various parts of the world and in different time periods.

scholarly journals Conception of a macroseismic catalogue for Catalonia (Spain)

1996 ◽  
Vol 39 (5) ◽  
Author(s):  
M. T. Susagna ◽  
X. Goula ◽  
A. Roca
Keyword(s):  
Geographic Location ◽  
Seismic Hazard Assessment ◽  
Data Bank ◽  
Historical Research ◽  
North East ◽  
The North ◽  
Focal Parameters ◽  
Bank System ◽  
Instrumental Records ◽  
Macroseismic Information

Since 1989 the Servei Geològic de Catalunya has been collecting macroseismic information of the North East of Spain and the South of France to create a comprehensive and reliable Catalogue which would be of use in seismic hazard assessment. Existing compilations have been submitted to a critical analysis and comparison, bearing in mind the resu1ts of recent historical research. For the seismicity of the present century macroseismic information is being studied by analyzing the original questionnaires. For each earthquake the felt intensities are stored on a data bank system. Due to the geographic location of the area under scrutiny, near the French border, collaboration with French agencies has been necessary to achieve joint information for Pyrenean earthquakes. Ancient instrumental records taken in two observatories (FBR and EBR) working since the beginning of this century have helped to determine focal parameters.

scholarly journals Materials for the investigation of The Seismicity Of Algeria And Adjacent Regions during the twentieth century

1994 ◽  
Vol 37 (4) ◽  
Author(s):  
D. Benouar
Keyword(s):  
Twentieth Century ◽  
Professional Training ◽  
Civil Protection ◽  
Local Conditions ◽  
Additional Information ◽  
Hazard And Risk ◽  
Recent Earthquakes ◽  
Integrated Study ◽  
Macroseismic Information ◽  
Reporting Procedures

Dr. Benouar presents a full and integrated study of the recent seismicity of Algeria and adjacent regions during the twentieth century. He has amassed an impressive amount of macroseismic information pertaining to individual earthquakes, which he combines with instrumental information to reassess the origin parameters of each event. In any compilation of earthquakes it is the additional information beyond the bare accumulation of figures and facts that adds interest and social understanding to the scientific appreciation of the earthquakes themselves. For this it is necessary to know the local conditions, and Dr. Benouar brings out for us very vivid1y the differences between reporting procedures at different times this century, and the ensuing difficulties. It would be most difficult for an outsider to gather the information he presents, and he makes good use of his knowledge of his native land, as well as his professional training as an engineer. We thus learn of the reluctance of the colonial powers to report on damage or casualties outside those inflicted on the expatriate community, and the general difficulties of finding information about earthquakes that occurred during the wars of independence, at a time when effects of even major earthquakes were sometimes minor compared to those of the war itself. He also does not spare us details of political difficulties that arose during periods of reconstruction following recent earthquakes. This work is not restricted, however, to description. He examines the underlying tectonics of the area and deduces estimates of hazard and risk in various parts of the country. He then proceeds to examine the engineering consequences and discuss future needs for building codes and civil protection. Dr. Benouar has produced a work which could well form a model for those wishing to undertake comprelzensive studies of seismicity of other areas, and the measures needed to reduce the effects of catastrophic earthquakes.

scholarly journals The 1860 magnitude 6.1 Charlevoix, Quebec, earthquake: macroseismic information and interpretation

2021 ◽  
Author(s):  
M Lamontagne ◽  
K B S Burke ◽  
L Olson
Keyword(s):  
Macroseismic Information

scholarly journals The autumn 1919 Torremendo (Jacarilla) earthquake series (SE Spain)

2015 ◽  
Vol 58 (3) ◽  
Author(s):  
Josep Batlló ◽  
José Manuel Martínez-Solares ◽  
Ramon Macià ◽  
Daniel Stich ◽  
José Morales ◽  
...  
Keyword(s):  
Intensity Data ◽  
Similar Magnitude ◽  
Se Spain ◽  
Regional Seismicity ◽  
Earthquake Series ◽  
Data Points ◽  
Instrumental Recording ◽  
Definition Of ◽  
Intensity Data Points ◽  
Macroseismic Information

<p>On 10th September 1919 several slightly damaging earthquakes struck the towns of Torremendo, Jacarilla (near Alicante, SE-Spain) and others nearby. Available magnitude estimations for the largest two events of the series are M = 5 approx. They were earthquakes of moderate size and they occurred in a region where similar magnitude earthquakes, thoroughly studied, occurred recently (1999 Mula; 2002 Bullas; 2005 La Paca; 2011 Lorca). This makes these events of interest for a better definition of the regional seismicity. We study their sources from the analysis of the available contemporary seismograms and related documents. A total of 23 seismograms from 9 seismic stations have been collected and digitized. These seismograms contain records for the two main events and several aftershocks of the earthquake series. Finally 44 files, corresponding to 44 recorded single component records from the different events have been processed. The events have been relocated and their magnitudes recalculated. Also, original macroseismic information for these events was recovered. A macroseismic evaluation of the series has been performed. Intensity data points have been recalculated and macroseismic location and magnitude obtained. We conclude that these are the largest earthquakes occurred in the region since the beginning of instrumental recording, with Mw = 5.5 for the largest shock, and that the available data could be compatible with a thrust mechanism related to blind faults in the Bajo Segura region.</p>

Near-Field Ground Motions from the July 2019 Ridgecrest, California, Earthquake Sequence

2020 ◽  
Vol 91 (3) ◽  
pp. 1542-1555 ◽  
Author(s):  
Susan E. Hough ◽  
Eric Thompson ◽  
Grace A. Parker ◽  
Robert W. Graves ◽  
Kenneth W. Hudnut ◽  
...  
Keyword(s):  
Nonlinear Response ◽  
Hard Rock ◽  
Ground Motions ◽  
Near Field ◽  
Earthquake Sequence ◽  
Motion Models ◽  
Instrumental Observations ◽  
Ground Motion Models ◽  
Macroseismic Information ◽  
Population Center

Abstract The 2019 Ridgecrest, California, earthquake sequence, including an Mw 6.4 event on 4 July and an Mw 7.1 approximately 34 hr later, was recorded by 15 instruments within 55 km nearest-fault distance. To characterize and explore near-field ground motions from the Mw 6.4 foreshock and Mw 7.1 mainshock, we augment these records with available macroseismic information, including conventional intensities and displaced rocks. We conclude that near-field shaking intensities were generally below modified Mercalli intensity 9, with concentrations of locally high values toward the northern and southern termini of the mainshock rupture. We further show that, relative to near-field ground motions at hard-rock sites, instrumental ground motions at alluvial near-field sites for both the Mw 6.4 foreshock and Mw 7.1 mainshock were depleted in energy at frequencies higher than 2–3 Hz, as expected from ground-motion models. Both the macroseismic and instrumental observations suggest that sediments in the Indian Wells Valley experienced a pervasively nonlinear response, which helps explain why shaking intensities and damage in the closest population center, Ridgecrest, were relatively modest given its proximity to the earthquakes.

Seismic History of Central North Anatolian Region: New Contribution from Ottoman Archives

2020 ◽  
Vol 91 (5) ◽  
pp. 2590-2600 ◽  
Author(s):  
Karin Şeşetyan ◽  
Orhan Sakin ◽  
Serpil Sönmez ◽  
Mine Betül Demircioğlu Tümsa
Keyword(s):  
Eastern Mediterranean ◽  
Eastern Mediterranean Region ◽  
Primary Source ◽  
Archival Material ◽  
History Of ◽  
State Archives ◽  
Definition Of ◽  
Earthquake Effects ◽  
Macroseismic Information ◽  
Archive Material

Abstract Contemporary Ottoman sources bring a major contribution to the description of the seismic activity in the eastern Mediterranean region and are extensively used by historical seismologists. Among these, the documents of the Ottoman State Archives (Istanbul), and more specifically the correspondence of the local governors with the central authorities form a valuable source for the description of the earthquake effects in territories, which were under the Ottoman rule. Especially for the more recent periods, we observe that not only major earthquakes but also small-to-moderate-size events with local effects find their place in these documents. However, due to the complex and insufficiently categorized structure of the archival material, as well as the need for expertize in Ottoman language and history, except the sections covered in the works of N. Ambraseys and C. Finkel and a number of earthquake-specific studies, these documents are not yet fully exploited in the definition of the regional seismic history. In this pilot study, we investigate the Ottoman archive material related to earthquake effects in the central North Anatolian region and search for possible supportive or new contribution to the seismic history of the study area. The period of investigation is the nineteenth century, with occasional data also found for the pre and postperiod. The study revealed supportive information for 15 earthquakes that were already known to previous compilations, and data for 19 earthquakes that we categorize as new events, demonstrating the value of this primary source and the wealth of macroseismic information that can still be extracted, revealing earthquakes so far unknown as well as enriching the descriptive information related to already known ones.

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