The 1898 Mare Island earthquake occurred in Northern California on March 30 at 23:43 local time with a moment magnitude of 5.8–6.4 and a maximum Mercalli intensity of VIII–IX (Severe–Violent).

Damage amounted to $350,000 (about $10,700,000 inflation adjusted to 2018) and was most pronounced on Mare Island, a peninsula in northern San Francisco Bay.

The mechanism of the shock is unknown, but several independent investigations focused on different aspects to gain a better understanding of the intensity, magnitude, source fault, and epicenter of this pre-instrumental event.

It terminates in the south in a more gradual fashion at the Salton Sea where displacement transitions to a series of transform faults and spreading centers along the Gulf of California Rift Zone.

Toppozada et al. 1992 compared the isoseismal map from the event to those of earthquakes that occurred during the instrumental period to resolve the magnitude.

The isoseismals for intensity V, VII, and VIII were also compared for additional calibration, and 6.7 was presented as the magnitude of the event, which was presumed to have occurred on the southern Rodgers Creek Fault.

[8] Another seismologist re-examined the event following the 2014 South Napa earthquake and found that the heavy effects on Mare Island were the result of weak or deficient buildings.

[3] The isoseismal map from Toppozada & Real 1981 places the epicenter to the north of San Pablo Bay and shows elongated rings aligned NNW–SSE.

Other locations in Sonoma County that were severely affected included Schellville, Greenwood Estate, and near Petaluma Creek.

Analysis of the severity, location, and frequency of the aftershocks bolstered Toppozada et al. 1992's stance that the origin of the mainshock was the southern Rodgers Creek Fault.