The Međimurje (Croatia) Earthquake of 1738

Abstract

The 30 March 1738 earthquake with an epicenter near Čakovec in Međimurje (Croatia) is the largest known earthquake in the low-seismicity area that includes northernmost Croatia, northeastern Slovenia, southeastern Austria, and southwestern Hungary. So far, it has attracted very little attention in the seismological communities of those countries. It is missing or has wrong source parameters in all of the relevant earthquake catalogs (including the Seismic Hazard Harmonization in Europe (SHARE) catalog, Stucchi et al., 2013), which may influence seismic hazard assessment in this part of Europe, most critically in the Međimurje region itself. We present contemporary historical data shedding some light on the effects that the earthquake had on settlements mostly in Međimurje, but also elsewhere in Croatia, Slovenia, and Hungary. We were able to assign intensities to 12 localities surrounding the epicenter and to resolve the confusion about its date of occurrence. The intensity points were inverted for the location of the macroseismic hypocenter and epicentral intensity (I0=7.9 MSK [Medvedev–Sponheuer–Karnik]). The epicenter is found to lie on the hanging wall of the reverse Čakovec fault, about 6 km from its surface trace, and 8 km north-northwest of the town of Čakovec. The rather small felt area for an earthquake of this maximum intensity implies a shallow macroseismic focal depth of 6 km. These values of intensity and depth correspond to a macroseismic magnitude of MLm 5.1.

Earthquakes of 1838 and 1839 in the Slovene Hills (Slovenia)-Međimurje (Croatia) area

“…One such earthquake, which occurred in 1738, was described by Herak et al (2020). This study is a continuation of the efforts initiated by Herak et al (2020) to gain better insight into the historical seismicity of the considered region.…”

“…However, as already noted by Herak et al (2020), the locations as well as the intensity and magnitudes of these two earthquakes are uncertain, and various catalogues (e.g. the CEC; Shebalin et al, 1974;Ribarič, 1982;Shebalin et al, 1998;Zsíros, 2000) list them with different epicentres and/or epicentral intensities.…”

“…General overview of the tectonic setting and of the historical seismicity of the wider region have been presented by Herak et al (2020) and will not be repeated here, as the two considered areas are close one to another. Let us just reiterate that the seismicity is weak nowadays (Fig.…”

“…BL -Balaton line; ČF -Čakovec fault; DF -Donat fault; LF -Ljutomer fault; MH -Međimurje Hills, SH -Slovene Hills. Modified after Herak et al (2020).…”

Constraints on Complex Faulting during the 1996 Ston–Slano (Croatia) Earthquake Inferred from the DInSAR, Seismological, and Geological Observations

“…The collected data (see above) permitted assigning intensity to 145 localities. Macroseismic field of the mainshock was modeled using the MEEP v.2.0 algorithm [37] modified as described in detail by [38,39]. Figure 6 presents Intensity Data Points (IDPs) in the epicentral area.…”