Markel Corp. suffered significant underwriting losses because of a tsunami in Japan, floods in Australia and an earthquake in New Zealand. Fortunately the specialty insurer and its chief executive, Kirshner, have their fingers in more than enough pies to stay secure. Locally the company invested in a fund that saved Short Pump’s West Broad Village development from bankruptcy. Among the city’s biggest philanthropists, the Markel family has kept a low profile this year. It’s probably a good thing, considering the lumps Markel took for getting involved with Justin French, the local developer convicted in early May for tax-credit fraud.