Indonesia's powerful earthquake may have affected the devastating mudflow in East Java.

The Sidoarjo Mudflow Management Board today said the massive crater had been spurting more mud than normal in recent days.

Nine villages - including thousands of homes, factories and rice paddy fields - have been buried by the mud, which started flowing from the site of a gas exploration well during drilling 3km underground more than a year ago.

Australian company Santos has an 18 per cent non-operating stake in the failed Banjar Panji exploration project.

The increase in mud coincides with a series of earthquakes in tremor-prone Indonesia, but the board's Achmad Zulkarnaen said it was too early to definitively say the two were connected.

"To say there's a link between the earthquake and increase in mudflow, we can not be certain of that," he said.

"But, from what our eyes can see, the mudflow volume has increased in the past three to four days.

"The mud has overflown from the first ring dam, the one surrounding the mudflow's central source.

"There's also increase in sulfuric gas outflow."

He said yesterday's powerful quake, and strong aftershocks, "thankfully" had not damaged the dirt embankments containing the mud.