Title: Stress drop variation of deep-focus earthquakes tables

Creator: Meichen Liu

Description of the data set: We intend to figure out the difference of stress drops, which is a characteristic source parameter, between shallow and deep-focus earthquakes. Significant stress drop difference may shed light on the difference of physical mechanisms of shallow and deep-focus earthquakes, which has been a elusive question. We select from deep-focus earthquakes (> 400 km) in 2000-2018 and obtain their stress drops using P and S waves. We find that stress drops of deep-focus earthquakes are about one order of magnitude higher than that of shallow earthquakes, indicating about one order of magnitude higher shear strength of shallow faults than faults in the mantle. The wide range of stress drops further suggests coexistence of phase transformation and shear-induced melting mechanisms of deep-focus earthquakes.

Methodology: The seismograms we used were downloaded from Incorporated Research Institutions for Seismology Data Manage Center (IRIS DMC). We then used a spectral method based on empirical Green's function to obtain corner frequencies of deep-focus earthquakes using these seismograms. Finally, we computed stress drops from corner frequencies assuming Brune's source model and a circular crack.

##----Description of each column in Table_1_P.csv and Table_1_S.csv----##
1.Number: the index of each event corresponding to the spectral ratios in the Supporting materials Figure S1.
2.Location: event locations. Events are basically divided into 3 parts, which are Northeastern Pacific, Fiji Tonga, and South America.
3.Time: the event occuring time.
4.Lat: the latitude of event epicenter in degree.
5.Lon: the longitude of event epicenter in degree.
6.Depth: the depth of event hypocenter in km.
7.Mw: the moment magnitude of the event.
8.fc(Hz): the obtained corner frequencies using spectral ratio method based on empirical Green's function.
9.tau(MPa): the computed stress drops assuming Brune's source model and a circular crack.

To cite this dataset: Liu, M. (2019) Stress drop variation of deep-focus earthquakes tables [Data set]. University of Michigan - Deep Blue. https://doi.org/10.7302/sp05-y333