Figure 5. Comparison of depths of earthquakes during 8–11 March 2023, at Tanaga Island calculated using: (a) the generalized Bancroft method, (b) HYPOINVERSE with the default HYPOINVERSE trial solution, and (c) HYPOINVERSE using the Bancroft result as the trial solution. Both HYPOINVERSE results

Figure 3. Maps of earthquake locations during 8–11 March 2023, at Tanaga Island calculated using: (a) the generalized Bancroft method, (b) HYPOINVERSE with the default HYPOINVERSE trial solution, and (c) HYPOINVERSE using the Bancroft result as the trial solution. The colorbar in panel

Figure 4. Histograms of the root mean square (rms) misfit of earthquake locations during 8–11 March 2023 at Tanaga Island calculated using: (a) the generalized Bancroft method, (b) HYPOINVERSE with the default HYPOINVERSE trial solution, and (c) HYPOINVERSE using the Bancroft result as the trial

Figure C-1. Spatiotemporal distribution of seismic activity. Dot color and size corresponds to the event origin time and magnitude, respectively. The number at the bottom right of each subgraph is the counts of earthquakes. (a–d) REAL, VELEST, HYPOINVERSE, and hypoDD location results in turn

Figure 3. Histogram of the root mean square (rms) difference between the HYPOINVERSE and Bancroft solutions using Charlevoix seismic‐zone real data. An rms D >0 represents a solution in which Bancroft produced a better rms than HYPOINVERSE, and rms D <0 represents a solution in which

Figure 2. (a) Comparison of Bancroft algorithm and HYPOINVERSE location residuals using synthetic data. Dark gray indicates Bancroft, and the black lines indicate HYPOINVERSE. Histograms are shown for latitude, longitude, depth, and origin time residuals calculated from the true and estimated

Figure 5. Histograms of the GDOP classified by rms value. For hypocenters with GDOP<∼4, Bancroft had fewer cases with smaller rms than did HYPOINVERSE. For hypocenters with GDOP>∼4, Bancroft had more cases with smaller rms than did HYPOINVERSE.

Table 3 Hypocentral Parameters for the 15 and 16 May 1951, Seismic Events Obtained in the Present Study Using the HYPOSAT and HYPOINVERSE‐2000 Version hyp1.40 Location Codes 15 May 1951 16 May 1951 Parameter HYPOSAT HYPOINVERSE HYPOSAT HYPOINVERSE Origin time (GMT

Figure 5. One‐dimensional velocity models. Blue is used for HYPOINVERSE locations and regional moment tensor inversion, based on Pechmann et al. , 1995 . Red is our preferred model from VELEST inversions used for single‐event VELEST and relative hypoDD relocations. Based on VELEST inversions

Figure 7. A map view showing the 30 well‐located earthquakes with initial HYPOINVERSE locations as red circles and HypoDD locations as green circles. The HypoDD locations of the 10 large earthquakes are shown as blue circles, with error ellipses from the original HYPOINVERSE location. The thickly

Figure 3. (a) Map view of six HYPOINVERSE locations with their horizontal location errors (95% confidence level). The circle sizes are scaled by their local magnitudes. (b) Map view of double‐difference (DD) locations using the phase data only. The mainshock focal mechanism is shown, and thin

, is not plotted since it was inoperable during March 2023. Contours of GDOP values equal to 5 are plotted as the black thick lines and HYPOINVERSE locations within the GDOP = 5 contour are expected to be of good quality ( Gómez et al. , 2015 ). The different plots show that GDOP decreases at shallower depths

Figure 4. (a) Map view of 36 HYPOINVERSE locations with their horizontal and vertical location errors. (b) Map view of double‐difference (DD) locations using only the phase data (event 8 not relocated). The mainshock focal mechanism is shown, and black lines indicate two nodal planes. The main

Figure 4. (a). Map view of HYPOINVERSE location of 19 events; (b) cross-section A–B of HYPOINVERSE locations; (c) cross-section C–D of HYPOINVERSE locations; (d) map view of double-difference locations using only phase data, event 13 was an outlier and not located; (e) across-strike cross-section

Figure 3. Map showing the 268 earthquakes relocated by the HYPOINVERSE/VELEST steps (white dots), and the 427 events that were relocated up through the hypoDD double‐difference algorithm (black dots). About 85% of the events locate on the Pa–NA plate boundary within the GoC . Note

Figure 2. Location errors calculated with the Hypoinverse code ( Klein, 2002 ). Triangles (left frame) are the rms of the time residuals versus horizontal errors ( ERH ) in kilometers. The right frame is the rms versus the vertical errors ( ERZ ) of the initial locations.