In the ballpark? That leaves a lot of room for major mistakes,
and major errors in measurements.
Vulcanoes exist everywhere on the planet, and most are even underwater, which makes it virtually impossible for vulcanologists to take accurate measurements, and which also means that, most volcanoes will go "unmeasured" ,which again brings up the question about the accuracy of any estimates. Estimates are prone to major errors. That's why estimates don't enter into the requirements of good scientific research.