Herculaneum was a more leisurely town about a third of the size of Pompeii and about a quarter of the population. Herculaneum did not have a major harbor nor was it a trade center.
Pyroclastic surges are responsible for the deaths in each city.
Excavations began at both cities in the 18th century. Deposits at Pompeii are dominated by air fall deposits of pumice and lapilli. Deposits at Herculaneum are dominated by pyroclastic flow deposits. Air fall deposits tend to be soft and can be scraped away with a shovel. Pyroclastic flow deposits tend to be hard because the hot ash tends to fuse together.