caa a22 4500 606149295 CHVBK 20210128100533.0 cr unu---uuuuu 210128e20150901xx s 000 0 eng 10.1007/s00531-015-1217-8 doi (NATIONALLICENCE)springer-10.1007/s00531-015-1217-8 Rupture process for micro-earthquakes inferred from borehole seismic recordings [Elektronische Daten] [Taka'aki Taira, Douglas Dreger, Robert Nadeau] We investigate the spatial extent of rupture and variability in fault slip for micro-earthquakes by inverting seismic moment rate functions derived from empirical Green's function deconvolution. By using waveforms from an array of borehole seismometers, we determine the spatial distributions of fault slip for M 3+ earthquakes that occurred along the Hayward fault in central California and identify a variety of slip behaviors including subevents, directivity, and high stress drop. The 2013 M w 3.2 Orinda earthquake exhibits a complex rupture process involving two subevents with northwest and up-dip directivity. The two subevents release 43 and 18% of the total seismic moment (6.7×1013Nm), and their inferred peak stress drops are 18 and 8MPa. The 2011 M w 4.0 Berkeley and 2012 M w 4.0 El Cerrito earthquakes are marked by high stress drop. The inferred peak and mean stress drops are about 100-130 and 40MPa, respectively, which suggests that there are locally high levels of fault strength on the Hayward fault. Our finite-source modeling suggests that the radiation efficiency determined for these two earthquakes is very low (<0.1) and implies that most energy is dissipated during the earthquake rupture process. The Author(s), 2015 Earthquake rupture nationallicence Earthquake stress drop nationallicence Finite-source rupture inversion nationallicence Hayward fault nationallicence Taira Taka'aki Berkeley Seismological Laboratory, University of California, 94720, Berkeley, CA, USA aut Dreger Douglas Berkeley Seismological Laboratory, University of California, 94720, Berkeley, CA, USA aut Nadeau Robert Berkeley Seismological Laboratory, University of California, 94720, Berkeley, CA, USA aut International Journal of Earth Sciences Springer Berlin Heidelberg 104/6(2015-09-01), 1499-1510 1437-3254 104:6<1499 2015 104 531 https://doi.org/10.1007/s00531-015-1217-8 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s00531-015-1217-8 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Taira Taka'aki Berkeley Seismological Laboratory, University of California, 94720, Berkeley, CA, USA aut NATIONALLICENCE 700 1- Dreger Douglas Berkeley Seismological Laboratory, University of California, 94720, Berkeley, CA, USA aut NATIONALLICENCE 700 1- Nadeau Robert Berkeley Seismological Laboratory, University of California, 94720, Berkeley, CA, USA aut NATIONALLICENCE 773 0- International Journal of Earth Sciences Springer Berlin Heidelberg 104/6(2015-09-01), 1499-1510 1437-3254 104:6<1499 2015 104 531