GEOPHYSICS SEMINAR

[Earth System Physics Section]

ESP GEOPHYSICS SEMINAR
LIVE and on Zoom
Monday, 5 December, 11:00 am
Euler Lecture Hall, ICTP Leonardo Building

Richard Walker
Dept. of Earth Sciences
University of Oxford, UK
on Sabbatical at ICTP, Geophysics group

THE EARTHQUAKE RUPTURES OF IRAN AND CENTRAL ASIA

The last century has seen unprecedented urban growth in regions of 
earthquake hazard within the continents*.*In contrast to plate 
boundaries, where earthquake hazard is usually confined to narrow zones 
around the edges of the oceans, active faulting within continental 
interiors is spread across very wide regions,and with intervals of 
hundreds, or even thousands of years between large earthquakes in any 
one area. The long recurrence intervals pose challenges for 
identification of active faults, and the small database of recent large 
earthquakes limits our understanding of fault rupture processes in such 
regions.There is a growing realisation that active faults deep within 
continental interiors behave in ways that are unexpected given the 
present understanding of global earthquakes and fault rupture. Tectonic 
motions in continental interiors are accommodated across diffuse 
networks of faults, and the occurrence of large earthquakes over 
historical times suggests that they may be clustered in particular 
regions at particular times, and may have complex multi-fault sources. 
These factors have profound implications for the applicability of 
established scaling relationships to estimate future magnitude, as 
earthquakes could be significantly larger than expected for a given 
fault length.

Iran and central Asia offer a natural laboratory for the study of plate 
interior earthquake occurrence, due to the relatively large number of 
events, the long historical and archaeological records, and the pristine 
environment that allows identification and study of earthquake ruptures 
far into prehistory. In this presentation I describe ongoing efforts to 
build an understanding of the sources of major earthquakes that have 
occurred in past centuries and millennia. Particular focus is placed on 
a number of large earthquakes that occurred within the early to mid 
20^th  century, which offer a bridge between the interpretation of 
modern and historic seismicity. We bring together elements of 
seismology, remote sensing, field geology, and quaternary dating to 
probe the rare, but potentially devastating occurrence of the largest 
earthquakes across the Asian interior.


Register in advance for this meeting:
https://zoom.us/meeting/register/tJIkf-ugpjsjEtc4QYISac-uKDiLOJXWRrLn
After registering, you will receive a confirmation email containing 
information about joining the meeting.