 The withdrawal of the sea that exposed an additional of beach created an even more significant warning sign, but in some locations wind waves on the sea effectively concealed the withdrawal that signalled the approach of the tsunami.The earthquake and tsunami came on a Monday afternoon, a day after many more people were present on the beach, due to a major national holiday.The waves came a few tens of minutes after the shock (and were a surprise, even to lifeguards) and occurred when the sea level was approaching low tide which, along with the wind waves, masked the initial withdrawal of the sea as the tsunami drew near.