Tsunami preparedness has come a long way in the eight years since the Indian Ocean tsunami ripped through South Asia, killing more than 225,000 people. The question is, has it come far enough?

The answer, provided last week by a high-magnitude yet essentially waveless earthquake off the coast of Sumatra, was a resounding “sort of.”

The 8.6 magnitude quake, which struck April 11, triggered the sprawling Indian Ocean tsunami warning system and caused many countries to issue alerts. The warnings were well heeded and since more people have cell phones than they did in 2004, they were also better communicated to friends and family. Years of preparedness drills guided people to where to go.

Despite these improvements, some think that if the wall of water had come, many would have died. Broken sensor buoys, sirens without battery back up, and the sheer mass of people that would need to migrate to higher ground could all contribute to tragedy, experts said.

“The tsunami alert system worked to a degree,” Keith Loveard, chief risk analyst at Jakarta-based Concord Consulting told Reuters. “The simple message is that in any critical condition like this it's impossible to get everyone out in time.”

Even so, getting everyone out is the aim—one that is more within reach now that the famously delayed alert system is operational, according to IRIN reports. As late as 2010, the system was plagued with data holes caused by damaged buoys that hold sensors to monitor ground shaking and water movement and by a lack of sirens in remote locations.

Nearly 450 died that year when alarms failed to sound in remote areas of the Mentawai Islands. Although the buoy data gaps are shrinking, sirens are still a problem. It took more than 30 minutes to activate sirens in the more densely populated Aceh region thanks to power outages caused by the earthquake, a disaster agency official told Reuters.

“We understand that the ideal is to warn people of a tsunami five to 10 minutes after a quake. I wished we could have,” he said. “The power was cut completely and the operators were too scared to turn on the backup power because we saw wires dangling in the street. We decided to turn on the siren in the end.”

Staying informed is only half the battle. Even when people are getting the message, they can face obstacles in getting to safety. In Sri Lanka, the alert system was augmented by personal technology, but evacuees still faced issues related to congestion.

“The mass media, mobile telephones and [short messaging] mainly contributed to getting the word out,” World Vision’s Suresh Bartlett told the Los Angeles Times. “The news got to everybody. Of course the roads were a bit congested as people tried to get to higher ground.”

It may be time to focus more strongly on evacuation issues, considering seismologists are predicting more strong earthquakes in the Sumatra area, according to AlertNet.

Although slip-strike quakes like last week's are less likely to generate tsunamis, some think that quake put even more stress on the nearby Sunda megathrust, increasing the likelihood of future tsunami-generating earthquakes.

“We've had so many big earthquakes around in Sumatra in the past few years,” Earth Observatory of Singapore Director Kerry Sieh told Reuters, “that it seems like an awful lot of the faults around there seem ready to go.”

Fortunately, last week’s quake was a painless way for South Asian governments to assess what was right and wrong with their tsunami alert systems, and few seemed happy to rest on their laurels.

“It is during such moments that the effectiveness of our work on preparedness and early warning can be assessed,” Ignacio Leon-Garcia, head of the United Nations Office for the Coordination of Humanitarian Affairs, told ChannelNews Asia. “We must never let our guard down—there is always room for improvement.”