The Observer's 20 photographs of the week

The most dramatic images this week again came from the erupting Mount Sinabung in Indonesia and also from vigilantes in Mexico. Here, in the village of Beras Tepu, a man walks in front of Mount Sinabung which continues to spew hot ash Photograph: Beawiharta/Reuters

And here, a lizard stands on an ash-covered leaf in the village of Beras Tepu Photograph: Tarmizy Harva/Reuters

More than 25,000 people have fled their homes as Mount Sinabung continues to erupt Photograph: Sutanta Aditya/AFP

Matches were interrupted at The Australian Open in Melbourne by extreme heat. Jerzy Janowicz of Poland here cools off in front of fans Photograph: Vince Caligiuri/Getty

Serena Williams hits a return to Daniela Hantuchova during their match at the Australian Open. Temperatures reached 40C and after winning the match, Williams said, 'It's definitely hot, but you have to be ready to play.' Photograph: Jason Reed/Reuters

Israel's President Shimon Peres lays a wreath during the funeral of former Israeli prime minister, Ariel Sharon, near Sycamore Farm, Sharon's residence in southern Israel Photograph: Baz Ratner/Reuters

Boys stand in front of a damaged wall which witnesses said was hit during an Israeli air strike in Gaza City. Israel's Iron Dome missile defence system intercepted five rockets fired at the city of Ashkelon from the Gaza Strip, and the military responded with a series of air strikes on the Hamas-controlled territory Photograph: Mohammed Salem /Reuters

Photographer Siegfried Modola produced strong work this week from the Central African Republic. Here, a fisherman paddles his boat on the river Oubangui in the capital Bangui Photograph: Siegfried Modola/Reuters

And here, in a contrasting image, anti-balaka militiamen are photographed by Siegfried Modola on the outskirts of Bangui. Central African Republic President Michel Djotodia agreed to resign this week over his failure to stem widespread violence between Muslims and Christians Photograph: Siegfried Modola/Reuters

And in this final image, people take shelter next to a derelict plane at a temporary camp for internally displaced persons at the airport of Bangui Photograph: Siegfried Modola/Reuters

A man rides his horse through the flames during the Luminárias annual religious celebration in the village of San Bartolomé de los Pinares. According to tradition that dates back 500 years, people ride their horses through the narrow cobblestone streets of this small village to purify the animals with the smoke of the bonfires Photograph: Juan Medina/Reuters

Swans swim near riverside properties partially submerged in floodwaters at Henley-on-Thames. More than 1,700 homes and businesses have been affected by the floods in England since late December Photograph: Toby Melville/Reuters

Vigilante 'El Love' leaves an almost empty walk-in closet in the house of a leader of the Caballeros Templarios, or Knights Templar, in Nueva Italia, Mexico. The drug lord and his family left the house as they fled an uprising led by farmers exasperated with organised crime Photograph: Jorge Lopez/Reuters

From the same set of images by Jorge Lopez in Mexico, a vigilante aims his weapon out of a car window while driving in a convoy to Poturo. The vigilantes who have been tolerated by the government, are pushing into the stronghold of one of Mexico's most feared drug cartels, raising the risk of an unprecedented urban battle Photograph: Jorge Dan Lopez/Reuters

And here, a looter carries boxes of beer as a truck burns in a roadblock allegedly set up by followers of the Knights Templar cartel in Tierra Caliente. Mexico's government pledged to take control of a violent western state after days of fighting between the vigilantes and the drug cartel Photograph: Stringer/Reuters

An Afghan child carries bread through the old quarters of Kabul Photograph: Johannes Eisele/AFP

Dawoodi Bohra Muslims crowd around the vehicle carrying the body of their spiritual leader Syedna Mohamed Burhanuddin during his funeral procession in Mumbai. At least 18 people died in a stampede after thousands gathered to mourn the death of the 102-year-old leader of a Muslim sect Photograph: Danish Siddiqui/Reuters

Ukrainian pro-government lawmaker Volodymyr Malyshev wipes blood from his face after a fight in parliament during a debate on the 2014 budget Photograph: Sergei Chuzavkov/AP

A two-headed turtle is pictured at its owners home in Qingdao, China. According to the turtle's owner, its two heads co-operate well and can even eat at the same time Photograph: Corbis

People take part in the 'No Pants Subway Ride' on the platform at the Potsdamer Platz station in Berlin. 'No Pants Subway Ride', is an annual worldwide event in which passengers ride trains without wearing trousers or skirts Photograph: Odd Andersen/AFP/Getty