The Verny, 1887, earthquake in Central Asia: Application of the INQUA scale, based on coseismic environmental effects

The INQUA scale, based on coseismic environmental effects, appears to be a very promising tool to get long-term and reliable information on seismicity. However, it has to pass through comprehensive testing procedures. Results of the INQUA scale application to earthquake intensity calibration are presented, part of the worldwide testing of the scale. As a case study, the Verny, 1887, earthquake in Central Asia has been chosen. It was a large earthquake (felt over 2,000,000 km2) located in a region with a specific temporal and spatial organization of seismicity. Verification of magnitudes of some large past earthquakes is important for the correct understanding of regional seismotectonics and seismic hazard assessment. The work is based on the original materials collected by the expedition soon after the earthquake in the epicentral area. It is demonstrated that assessment of epicentral intensity derived from total area of secondary environmental effects is reliable. This enables evaluation of the parameters of historical earthquakes based on generalized information of observed earthquake environmental effects (EEE). The epicentral intensity I0 is assessed to be IX-X degrees; the highest observed local intensities are coherent with I0 assessment.