A recent earthquake in California left vineyard owners crying over spilt wine. The seismic shrug, the hardest that has occurred in the area in the last quarter of a century, struck wine-center Napa Valley the worst. To add insult to injury, the area was just on the brink of bringing in an early harvest to stave off damage done by the worst drought to strike in decades.

Aside from direct property damage, the 6.1-magnitude earthquake resulted in the injury of more than 170 people and started several fires. It is estimated that the quake would eventually total up a bill of more than a $1 billion once the dust settles.

California is prone to earthquakes because there are more than 100 active faults running through the state; it lies squarely in the path of the Mendocino Triple Junction, San Jacinto and San Andreas fault line, the last of which is where the Pacific and North American Plate rub shoulders in a horizontal motion (also known as a right-lateral strike-slip in geological terms). These faults have been there longer than Californians have been around, so earthquake damage is an eminently foreseeable, even inevitable event. And yet according to the California Earthquake Authority, only an average of 1 in 10 residents in the state has coverage for earthquake-related property damage. In the Napa Valley area, where the most recent earthquake struck hardest, only 6% of residents had earthquake insurance coverage.

This could partly be due to the fact that earthquake insurance coverage is not required of property owners, and it can be an expensive rider to the typical homeowners’ insurance, averaging out to about $860 a year. It may also be because the infrequency of major event lulls residents with a false sense of security; thousands occur every year, but most are so small that they are hardly felt. The most expensive earthquake in US history occurred twenty years ago in Northridge (6.7-magnitude), a community in Los Angeles, California. Between the Northridge and Napa Valley events, 28 notable earthquakes occurred, ranging in magnitude between 4.4 and 7.2, many of which occurred in remote or unpopulated areas, minimizing the damage.