The natural disaster is EARTHQUAKE.
On the 8th of October, 2005, the Kashmir region of India and some sections of Pakistan and Afghanistan was hit by an earthquake. The earthquake had a magnitude of 7.6. The earthquake caused a lot of damages and a huge number of people lost their lives during the event, many more become homeless.
Yes, technically it is true that the Byzantine emperor, who believed that Muslims posed a threat to Christian Constantinople, requested help from Europe, although he mostly dealt with them himself.