The earthquake history in a fault zone tells us almost nothing about m (sub max)

In the present study, we summarize and evaluate the endeavors from recent years to estimate the maximum possible earthquake magnitude m (sub max) from observed data. In particular, we use basic and physically motivated assumptions to identify best cases and worst cases in terms of lowest and highest degree of uncertainty of m (sub max) . In a general framework, we demonstrate that earthquake data and earthquake proxy data recorded in a fault zone provide almost no information about m (sub max) unless reliable and homogeneous data of a long time interval, including several earthquakes with magnitude close to m (sub max) , are available. Even if detailed earthquake information from some centuries including historic and paleoearthquakes are given, only very few, namely the largest events, will contribute at all to the estimation of m (sub max) , and this results in unacceptably high uncertainties. As a consequence, estimators of m (sub max) in a fault zone, which are based solely on earthquake-related information from this region, have to be dismissed.