Assessing infrequent large earthquakes using geomorphology and geodesy: the Malawi Rift

摘要: In regions with large, mature fault systems, a characteristic earthquake model may be more appropriate for modelling occurrence than extrapolating from short history of small, instrumentally observed earthquakes using the Gutenberg–Richter scaling law. We illustrate how geomorphology and geodesy Malawi Rift, region large seismogenic thicknesses, long scarps, slow strain rates, can used to assess hazard probability levels infrequent earthquakes. estimate potential size length recurrence intervals plate motion velocities generate synthetic catalogue events. Since it is not possible determine geomorphological information if future rupture will continuous (7.4 ≤ M W 8.3 1,000–4,300 years) or segmented (6.7 7.7 300–1,900 years), we consider both alternatives separately also produce mixed catalogue. carry out probabilistic seismic assessment regional- site-specific estimates. At all return periods vibration periods, inclusion fault-derived parameters increases predicted spectral acceleration above level instrumental alone, most significant changes being in close proximity systems effect at longer periods. Importantly, results indicate that standard analysis (PSHA) methods records alone tend underestimate hazard, especially damaging, extreme magnitude For many developing countries Africa elsewhere, which are experiencing rapid economic growth urbanisation, assessments incorporating models critical.