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Abstract:
This investigation searches for contemporary written documentation on damaging earthquake consequences in intraplate northern Europe between the late 1800s and early 1900s, when the region experienced a period of elevated seismicity of earthquakes with M < 5.5. Augmenting information is expected to improve the success of intensity assignment and the subsequent determination of non-instrumental magnitude and epicenter. Ultimately, such examples would provide helpful validation of the intensity scale. This is demanding, however, because damage levels in the region can typically be linked to the masonry parts of houses, timber being resilient to ground shaking, and only ordinary buildings are recommended to be used for intensity assessment by the EMS-98 guidelines.
Once the contemporary newspapers have been exhaustively scanned, the search for archived documentation about the non-structural earthquake impact faces several challenges. Many documents were not written in the first place for dwellings that sustained some damage, but were not insured. Documentation lost over the decades is all too familiar. Earlier work on an earthquake of 1898 showed that both direct and indirect earthquake effects occurred: Ground shaking cracked unreinforced masonry chimneys and stoves, which posed a serious fire hazard in predominantly wooden towns. Additional cases from 1882 and 1904 are explored. Indirect earthquake hazards can occur at long epicentral distances, but establishing a time frame for them can be difficult. Estimates of earthquake-related costs at a few localities are attempted. A reasonable assessment of the economic impact of past earthquakes would make them more existent outside the seismological community.
