On Aug. 6, the Indonesian island of Lombok was shaken for the second time in 10 days. A 6.9-magnitude earthquake struck the tourist haven, razing buildings, shattering roads and cutting off electricity.

A government-issued tsunami warning added to the panic, sending people running for higher ground, though the ensuing wave proved small. Thousands of people have fled. Crowds gathered on the beaches of the Gili Islands, off Lombok's northwest coast, to be shipped to safety.

The quake killed more than 400 people and injured more than 1,000. A smaller tremor that hit days before killed 17. Another struck on Aug. 9.

Several disasters have buffeted Indonesia's tourist spots in recent months. In late June, Mount Agung on the neighboring island of Bali began spewing ash and lava. Flights were grounded, leaving thousands of visitors stranded. Indonesia runs along the Pacific Ocean's "ring of fire," with 130 active volcanoes. Tectonic events are common. Of 164 earthquakes around the world since 2017 with a magnitude of 6 or more, 12 took place in Indonesia.

Other concerns loom over the tourism industry, too. In June, a ferry capsized on Lake Toba, a pristine destination on Sumatra, drowning 180 people. Officials later declared that the boat was grossly overcrowded. A rise in terrorism since 2014 is also a worry, even if tourists have not been directly targeted (as they were in the Bali bombing of 2002, when jihadists killed more than 200 people).

The risks aside, Indonesia is blessed with white beaches, exotic wildlife and eight UNESCO world-heritage sites. Marketing campaigns, better access to airports and a loosening of visa rules have boosted the number of annual visitors, from 7 million in 2010 to 14 million last year.

The government wants an annual 20 million visitors by 2020, increasing tourism's contribution to GDP from 5.8 percent, less than half the regional average, to 7.5 percent. Much of the growth is coming from Chinese vacationers, who have been lured away from Thai beaches. They account for about 14 percent of visitors, double the proportion in 2010.

Though Indonesia has 13,000 or so islands, two-fifths of its tourism is concentrated on just one: Bali. (Many Australians vacationing there, when asked whether they have ever been to Indonesia, reply no.) In 2017, in an effort to spread the gains from tourism, President Joko Widodo, or Jokowi, announced a policy to roll out Bali's success across the rest of Indonesia — his "10 Balis" plan.

In some quarters, including in the government, the plan has caused concern, in particular about the potential damage to the environment. Bali itself has problems with ugly development, untreated sewage spewing into the ocean and plastic waste littering the beaches.

Some of Jokowi's designated spots are nature reserves with fragile ecosystems. The national park near the town of Labuan Bajo on Flores, for instance, is home to Komodo dragons as well as a rich sea life; tourism could ruin special habitats if not carefully regulated. On Aug. 1, a fire burned 10 hectares of vegetation in the park. Police suspect a visitor's discarded cigarette.

Another hurdle to the plan is Indonesia's woeful infrastructure. The government estimates it needs $20 billion to spruce up all 10 proposed spots, half from foreign investors. The government has built seven new airports since 2014 and plans another eight in the next two years.

More flights are arriving at the airport close to Lake Toba, one of the new Balis. That saves an hourslong drive from Medan, the nearest city. The runway has been extended at Labuan Bajo, too. But access to other designated sites has not improved, said Matt Gebbie of Horwath HTL, a tourism consultancy.

A shortage of hotels looms in at least four of the proposed destinations, according to the Indonesian Hotel and Restaurant Association. Lake Toba needs another 2,000 rooms (with the strain on resources that would come with them, it is hard to know how the lake can remain pristine).

Even where there are ample rooms, finding qualified hotel staff to ensure guests' pillows are fluffed and cocktails are iced may be tricky. The government is working with 100-odd colleges to train a new generation of hoteliers, said Hiramsyah S. Thaib, the head of the 10-Bali program at the tourism ministry.