Browsing by Subject "macroseismology"

Sort by: Order: Results:

Now showing items 1-4 of 4
  • Mäntyniemi, Päivi Birgitta; Sørensen, Mathilde B.; Tatevossian, Tatiana N.; Tatevossian, Ruben E.; Lund, Björn (2020)
    Archives and libraries were visited to find previously unknown documents testifying to the Luroy, Norway, earthquake of 31 August 1819 in northernmost continental Europe. The focus here is on Sweden, Finland, and Russia, which are important for determining the area of perceptibility east of Norway. The new written sources include 12 notes or entries in original archived documents, six contemporary newspaper reports, and two recollections written down years later. The original documentation uncovered is contributory to establishing the authenticity of the observations in Finland and Sweden. The dates of the original documentation allow tracing of the dissemination of eyewitness accounts in writing from the inner area of perceptibility southward to the larger documentation and population centers. New sources of information include weather reports of the Royal Swedish Academy of Sciences, minutes of its meetings, and correspondence sent to the Senate in Finland. The minutes of meetings of the Academy indicate that ample data were collected in the Swedish province of Vasterbotten. We found no original Russian documentation but uncovered national newspapers that are more reliable than the previously used Parisian newspaper. To increase transparency, we provide the first list of macroseismic data points (MDPs) including the respective documentation that testify to the Luroy earthquake. A macroseismic intensity was assigned to a locality, using the European Macroseismic Scale of 1998, when adequate information was available. Accounting for the uncertainty of intensity assessment, the magnitude was estimated as moment magnitude M = 5.9 +/- 0.2, reconfirming the ranking as the largest onshore or nearshore earthquake in the historical seismicity record of Fennoscandia. In addition to the reappraisal of the 31 August 1819 earthquake, a macroseismic map is provided for the earthquake of 17 February 1819, which was felt in northern Finland and Sweden. Some of its MDPs were previously associated with the Luroy earthquake.
  • Mäntyniemi, Päivi (2017)
    The present article is the first part of a snapshot of macroseismology in Finland from the 1730s to the 2000s. In the 1730s, more numerous and informative earthquake reports began to appear. Continuing up until the early 1880s, these reports were often by-products of compilations of statistics and weather conditions; afterwards, felt earthquake observations were the objective of specific macroseismic surveys. During the Swedish era until 1809, earthquake reports are attributed to the developing press, the Royal Swedish Academy of Sciences and the Statistical Office. In the Grand Duchy of Finland, learned societies collected data on different natural phenomena. In the Republic of Finland since 1917, the designing and use of macroseismic questionnaires shifted to the established seismological units. The designing and dissemination of macroseismic questionnaires constitute the core of macroseismic surveys in Finland. This part focuses on the design. Seven generations of printed macroseismic questionnaires are identified. The first questionnaire in 1882 was designed by a geologist. The second-generation questionnaire was produced by the Geological Commission. In the 1900s, the third-generation questionnaire was owned by the Geographical Society of Finland, the fourth by the seismological station of the University of Helsinki, the fifth by the Sodankylä Geophysical Observatory of the Finnish Academy of Science and Letters, the sixth by the Department of Geophysics of the University of Oulu and the seventh of the Institute of Seismology of the University of Helsinki. At the turn of the 2000s the questionnaire was placed on the Internet.
  • Mäntyniemi, Päivi Birgitta (2017)
    The present article is the second part of a snapshot of macroseismology in Finland from the 1730s to the 2000s. In the 1730s, more numerous and informative earthquake reports began to appear. The article begins with an outline of the connection between academia and macroseismology. The focus is on the dissemination of macroseismic questionnaires and their respondents. The standard practice in Finland is to conduct macroseismic surveys remotely. Postal services were widely used to disseminate questionnaires in the areas affected by earthquakes. The newspaper press has frequently been utilized in the surveys. Since the latter half of the 1800s, telephones and telegraphs made instant communication possible. Macroseismic field surveys have sometimes been conducted after important local earthquakes to interview eyewitnesses and to disseminate questionnaires on the spot. The group of earthquake reporters that stands out throughout the centuries is the clergy. Its leading position waned only in the 1900s. Finns became more literate, acquiring their writing skills during the 1800s. The occupational groups of the respondents became more versatile in the 1900s, reflecting the evolution of macroseismology into a genuine citizen science. Macroseismic reporting mirrors the development of society throughout the centuries. In particular, new technologies have an immediate effect on the surveys.
  • Vakarchuk, Roman N.; Mäntyniemi, Päivi Birgitta; Tatevossian, Ruben E. (2019)
    The present investigation focuses on the effect of input data properties on the estimation of seismic intensity prediction equation (IPE) coefficients. Emphasis is placed on small-tomoderate magnitude earthquakes. Synthetic intensity data points (IDPs) are created using a given IPE, assuming independence of azimuth. Extensive simulations are performed for single earthquakes and a synthetic database. Tests of single earthquakes show that increasing the sample size narrows the range of obtained coefficients. The larger the difference between the shortest and longest distance of IDPs from the epicentre, the narrower is this range. A short radius of perceptibility is more rapidly saturated with new data points than a long one. The synthetic database is used to examine the effect of magnitude and depth errors. The performance of synthetic data gives a model with which the real data can be compared. The attenuation coefficient appears stable against magnitude errors of +/- 0.2 units, but starts to be overestimated as magnitude errors increase. Assuming an erroneous regional depth easily leads to intensity differences of 1 degree. The mean coefficient values deviate from the correct ones and tend to increase with depth. The results resemble the synthetic ones, but imply larger uncertainties. The attenuation coefficient, m, appears to be the least sensitive coefficient to errors. Real data from seven post-1965 earthquakes in the magnitude range of 4.0-5.2 were retrieved from the intensity database of the United Kingdom.